AP State Board Syllabus AP SSC 10th Class Biology Important Questions Chapter 1 Nutrition.

AP State Syllabus SSC 10th Class Biology Important Questions 1st Lesson Nutrition

10th Class Biology 1st Lesson Nutrition 1 Mark Important Questions and Answers

Question 1.
Define photosynthesis. (OR) What is photosynthesis?
Answer:
Photosynthesis is the process by which plants containing the green pigment called chlorophyll which build up complex organic molecules from relatively simple inorganic ones using sun light as an energy source.

Question 2.
What is the balanced equation to show the process of photosynthesis?
Answer:

Question 3.
Bhumika told that “If there were no green plants, all life on the earth would come to an end” Comment.
Answer:
All the living organisms on the earth depends on the plants either directly or indirectly for the food and oxygen.

Question 4.
Which disease occurs in child when there is an immediate second pregnancy or repeated child births in a mother?
Answer:
Marasmus

Question 5.
Give two examples for nutritional deficiency diseases.
Answer:
Nutritional deficiency diseases: Kwashiorkor, Marasmus, Beri-Beri, Glossitis, Pellagra, Anemia, Scurvy, Rickets, etc.

Question 6.
Your neighbour’s children appear with swollen legs, hands and other body parts. They have dry skin and frequently suffering from Diarrhoea. What are the reasons for it ? What suggestions do you give to their parent ?
Answer:
The children appear with swollen legs, hands and other body parts. They have dry skin and suffering from diarrhoea.
The reason for it is malnutrition and they are suffering from Kwashiorkor and Marasmus diseases.
They are advised to take proteins and calorie rich foods like liver, meat, eggs, milk, fruits, cereals and leafy vegetables.

Question 7.
What suggestions do you give to your friend suffering from constipation?
Answer:
Constipation can often be avoided by
a) having plenty of roughages in our daily diet. Ex : Leafy vegetables, beans, cabbage, etc.
b) drink plenty of water daily.
c) avoid junk food,
d) swallow the food only after its thorough mastication.

Question 8.
Which organelle of the leaf absorbs energy from the sunlight for photosynthesis ?
Answer:
Chloroplast.

Question 9.
Which gas is evolved in the diagram experiment? How can this gas be tested for confirmation?

Answer:
i) Oxygen gas is evolved in this experiment.
ii) If the burning splinter is kept near the mouth of the test tube, it burns brightly.

Question 10.
Classify the following vitamins into water soluble and fat soluble
i) Riboflavin ii) Retinol iii) Tocoferol iv) Thiamin
Answer:
Water soluble vitamins : Riboflavin (B₂), Thiamin (B₁)
Fat soluble vitamins : Retinol (A), Tocoferol (E)

Question 11.
Prepare your own tabular column to get information about food deficiency diseases from a doctor.
Answer:

Question 12.
Why is KGH used in Mohl’s half leaf experiment? (OR)
Why do we use KOH solution in Mohl’s half-leaf experiment?
Answer:
1) We conducted Mohl’s half leaf experiment to prove CO₂ is essential for photosynthesis.
2) So KOH is used in this experiment to absorb the CO₂ present inside the bottle.

Question 13.
What questions will you ask a doctor to know about malnutrition ?
Answer:

1. What is malnutrition?
2. What are the causes for malnutrition?
3. What are the different types in malnutrition?
4. How can we overcome the malnutrition?
5. What are the reasons for malnutrition in our country?

Question 14.
Name the vitamin which is synthesized by the bacteria present in the human intestine.
Answer:
B₁₂ (Cyanocobalamine) is the vitamin which is synthesized by the bacteria present in the human intestine.

Question 15.
Which digestive juice doesn’t contain enzymes ?
Answer:
Bile juice which is produced by liver doesn’t contain enzymes. But it converts fats into small globules. This process is called emulsification.

Question 16.
One student takes high calorie food. Another student takes less calorie food. But both are affected with diseases. Name the diseases by which they are affected.
Answer:
Student takes high calorie food affected by – Obesity.
Student takes less calorie food affected with – Marasmus.

Question 17.
Mention the two chemicals which you have used in an experiment to test the presence of starch in the leaf.
Answer:
The chemicals used in an experiment to test the presence of starch in the leaf are

1. Methylated spirit
2. Iodine solution.

Question 18.
18. Write two slogans for campaign on Mal-nutrition.
Answer:

1. Be cool and say no to fast food.
2. Be smart – Eat smart
3. Eat healthy – Look healthy – Feel healthy

Question 19.
Identify the two parts A and B indicated in the given figure.

Answer:
A – Stomach
B – Large intestine

Question 20.
Doctors advise not to eat food items at the time of fever. What are the reasons for this ?
Answer:

1. At the time of fever body temparature is high.
2. At that time digestive enzymes do not properly work to digest food.
3. That’s why doctors advise not to eat food items at the time of fever.

Question 21.
If we chew the grains like wheat, jowar, rice we feel sweet. Why?
Answer:

1. The grains like wheat, jowar, rice contain carbohydrates.
2. Ptyalin acts on them and coverts them into sugars. So we feel sweet.

Question 22.
What teeth you use when you eat peas and banana? Why?
Answer:

1. Premolars and molars are used when we eat peas and banana.
2. Their function is to chew and grind the seed and food material.

Question 23.
What is autotrophic nutrition?
Answer:
It is a type of nutrition in which an organism makes its own food from the simple inorganic materials like carbon dioxide and water using light as source of energy.

Question 24.
What is nutrition ?
Answer:
Nutrition: Nutrition is the process of intake or procurement of nutrients.

Question 25.
What are the main modes of nutrition ?
Answer:
Autotrophic nutrition and heterotrophic nutrition are the main modes of nutrition.

Question 26.
What are different types of heterotrophic nutrition ?
Answer:
Heterotrophic nutrition is of three types. They are:

1. Saprophytic nutrition
2. Parasitic nutrition and
3. Holozoic nutrition.

Question 27.
What are the symptoms of disease pellagra?
Answer:
Dermatitis, diarrhoea, loss of memory and scaly skin are the symptoms of disease pellagra.

Question 28.
Which vitamin deficiency causes Rickets ? What are its symptoms?
Answer:
Vitamin D Calciferol deficiency results in Rickets. The symptoms shown are improper formation of bones, knocknees, swollen wrists, delayed dentition, weak bones, etc.

Question 29.
For proper vision which vitamin is required? What is its chemical name?
Answer:
Vitamin A is required for proper vision. The chemical name of vitamin ‘A’ is Retinol.

Question 30.
What are the complex molecules produced by plants from simple Inorganic substances?
Answer:
Carbohydrates, proteins and lipids are produced from simple inorganic substances like water and CO₂.

Question 31.
What are the essential factors required for photosynthesis?
Answer:
Carbon dioxide, water, chlorophyll and sunlight are the essential factors required for photosynthesis.

Question 32.
What is the equation for photosynthesis proposed by C.B.Van Neil in the year 1931?
Answer:

Question 33.
In which form are carbohydrates stored in plants?
Answer:
Carbohydrates are stored in plants in the form of starch.

Question 34.
What is the reagent that is used to test the presence of starch in leaves?
Answer:
The reagent that is used to test the presence of starch in leaves is Iodine solution. The colour of the leaf will turn to blue-black in colour.

Question 35.
Who found that water was essential for the increase of plant mass?
Answer:
Von Helmont found that water was essential for increase of plant mass in the year 1648.

Question 36.
Who performed series of experiments in 1770 to reveal the role of air in growth of green plants?
Answer:
Joseph Priestly performed series of experiments in 1770 to reveal the role of air in growth of green plants.

Question 37.
What is the role of potassium hydroxide solution kept inside the glass bottle in the Mohl’s half leaf experiment?
Answer:
Potassium hydroxide solution kept inside the glass bottle in the Mohl’s half leaf experiment absorbs the carbon dioxide present inside the bottle.

Question 38.
Who found that gas bubbles liberated from hydrilla plant contain the gas oxygen?
Answer:
Jan Ingenhousz in 1779 found that the gas bubbles liberated from hydrilla plant contain the gas oxygen.

Question 39.
Who coined the term chlorophyll for the extract of green coloured substance from the leaf?
Answer:
Pelletier and Caventou in the year 1817 coined the term chlorophyll for the extract of green coloured substance from the leaf.

Question 40.
Chloroplast is formed by how many membranes?
Answer:
Chloroplast is formed by 3 membranes.

Question 41.
What is grana?
Answer:
Grana : The stacked sac like structures formed by the third layer of chloroplasts is called grana.

Question 42.
What is the function of stroma?
Answer:
It is believed to be responsible for enzymatic reactions leading to the synthesis of glucose, which inturn join together to form starch.

Question 43.
What is stroma?
Answer:
Stroma : The fluid filled portion of chloroplast is called as stroma.

Question 44.
What are the two major phases found in photosynthesis?
Answer:
The two major phases found in photosynthesis are:

Question 45.
Why is light reaction phase called photochemical phase?
Answer:
A series of chemical reactions occur in a very quick succession initiated by light and therefore the phase is technically called the photochemical phase.

Question 46.
Where does the light reaction take place?
Answer:
The light reaction takes place in chlorophyll containing thylakoids called grana of Chloroplasts.

Question 47.
What are the end products of light reaction?
Answer:
The end products of light reaction are O₂, ATP and NADPH.

Question 48.
What are called the assimilatory powers?
Answer:
ATP and NADPH formed at the end of the light reaction are called assimilatory powers.

Question 49.
What are dark reactions?
Answer:
Dark reactions: The reactions that occur in both presence or absence of light are called dark reactions. The occurance of dark reaction is independent of light.

Question 50.
Who observed dark reactions?
Answer:

1. The entire series of reactions involved in the conversion of CO₂ to glucose were identified by Melvin Calvin.
2. The dark reactions are also called as Calvin Cycle.

Question 51.
What is Calvin cycle?
Answer:
Calvin cycle: The cycle of reactions in fixation of carbon dioxide to glucose is called Calvin cycle.

Question 52.
How is glucose produced during dark reaction?
Answer:
In the dark reaction, the hydrogen of the NADPH is used to combine with CO₂ by utilizing ATP energy and ultimately produce glucose.

Question 53.
Write some of the events that occur in the chloroplasts during photosynthesis.
Answer:

1. Conversion of light energy to chemical energy.
2. Splitting of water molecule.
3. Reduction of carbon dioxide to carbohydrates.

Question 54.
What is photolysis of water? Which gas is released?
Answer:
Photolysis of water:

1. Photolysis of water Splitting of water molecule by light activated chlorophyll molecule is known as photolysis of water.
2. Oxygen is released during (photosynthesis) photolysis of water.

Question 55.
In which cells of the leaves photosynthesis takes place?
Answer:
The mesophyll cells of leaf containing palisade and spongy tissue photosynthesis takesplace.

Question 56.
What is the ultimate source of energy?
Answer:
The ultimate source of energy is the Sun.

Question 57.
What are guard cells?
Answer:
Guard cells: The two kidney shaped cells which surrounds the stoma are called guard cells.

Question 58.
How does CO₂ enter into leaf?
Answer:
CO₂ present in the atmosphere enters through stomata into the cells of leaf by diffusion.

Question 59.
What is the first stable product formed in dark reaction or photosynthesis?
Answer:
Phosphoglyceric acid or PGA is the first stable product formed in dark reaction or photosynthesis.

Question 60.
Why ATP and NADPH are required in photosynthesis?
Answer:
ATP and NADPH are required for the utilization of carbon dioxide and formation of glucose during photosynthesis.

Question 61.
Why chloroplasts are green in colour?
Answer:
Chloroplasts are green in colour due to the presence of a green colouring pigment called chlorophyll.

Question 62.
What are the examples for parasitic organisms?
Answer:
The examples for parasitic organisms are cuscuta (plant), lice, leeches and tapeworms (animals).

Question 63.
How does amoeba take food into the body?
Answer:
Amoeba takes in food using temporary finger like extensions called pseudopia of the cell surface.

Question 64.
How does paramoecium take food?
Answer:
Food is moved to the cytosome by the movement of cilia which covers the entire surface of the cell where the food is ingested.

Question 65.
What is ingestion?
Answer:
Ingestion : The process of taking food into the body is called ingestion.

Question 66.
Name the three pairs of salivary glands. What is the enzyme secreted by them?
Answer:

1. The three pairs of salivary glands in mouth are :
   i) Parotid glands
   ii) Submandibular glands and
   iii) Sublingual glands.
2. The enzyme secreted by salivary glands is amylase (ptyalin).

Question 67.
What is the role of amylase in digestion of food?
Answer:
Amylase helps in the breakdown of complex carbohydrates to simple ones.

Question 68.
What is digestion?
Answer:
Digestion : The process of breaking down of complex food substances into simple substances so that they can be used by the body with the help of enzyme is called digestion.

Question 69.
How does the food from oesophagus move into the stomach?
Answer:
Food passes through oesophagus by wave like movements called peristaltic movements and reaches the stomach.

Question 70.
What is chyme?
Answer:
Chyme : Chyme is a soft slimy substance of food in which some proteins and carbohydrates have broken down.

Question 71.
What is the function of sphincter muscle present at the exit of stomach?
Answer:

1. The sphincter muscle is responsible for regulating the openings of the stomach into small intestine.
2. So that only small quantities of the food material may be passed into the small intestine from the stomach at a time.

Question 72.
What does the gastric juice contain?
Answer:
The gastric juice secreted by the walls of stomach contains Hydrochloric acid, protein digesting enzyme, pepsin and mucus.

Question 73.
What makes the internal condition of the intestine gradually to a basic or alkaline one?
Answer:
Liver and pancreatic juice make the internal condition of the intestine gradually to a basic or alkaline one.

Question 74.
What is emulsification?
Answer:
Emulsification : Fats are digested by converting them into small globule like forms by the help of bile juice secreted from liver. This process is known as emulsification.

Question 75.
For what intestinal juice secreted by small intestine is responsible?
Answer:
The enzymes present in intestinal juice finally convert the protein to amino acids, complex carbohydrates into glucose and fats into fatty acids and glycerol.

Question 76.
What are the enzymes that act on proteins?
Answer:
Pepsin and Trypsin are the enzymes that act on proteins. Both these enzymes convert proteins to peptones.

Question 77.
What is absorption?
Answer:
Absorption : Transport of the products of digestion from the walls of the intestine into blood is called absorption.

Question 78.
What is defecation?
Answer:
Defecation: The passage of undigested material from the body by the way of anus is called defecation.

Question 79.
What are roughages in the food?
Answer:
Roughages are the fibres of either carbohydrates or fats which help in constipation.

Question 80.
What are the parts of human digestive system?
Answer:
Mouth, buccal cavity, pharynx, oesophagus, stomach, small intestine, large intestine, rectum and anus.

Question 81.
What is a balanced diet?
Answer:
Balanced diet: Diet containing nutrients in required amounts is known as balanced diet.

Question 82.
What are the nutrients present in balanced diet?
Answer:
Carbohydrates, proteins, fats, vitamins and mineral salts are the nutrients present in balanced diet.

Question 83.
What is malnutrition?
Answer:
Malnutrition : Eating of food that does not have one or more than one nutrients in required amount is known as malnutrition.

Question 84.
What are different types of malnutrition?
Answer:
Malnutrition is of three types. They are:

1. Calorie malnutrition
2. Protein malnutrition and
3. Protein calorie malnutrition.

Question 85.
What are the two sources of vitamins to our body?
Answer:
The two sources of vitamins to our body are one is diet and the other is bacteria present in the intestine synthesise enzymes and supply them to the body.

Question 86.
Vitamins are classified into how many groups?
Answer:
Vitamins are classified into two groups. They are fat soluble (eg : A, D, E and K) and water soluble (eg : B complex, Vitamin C).

Question 87.
What is the chemical name of vitamin B₁₂?
Answer:
The chemical name of vitamin B₁₂ is Cyanocobalamine.

Question 88.
Which vitamin deficiency causes sterility in males?
Answer:
Vitamin E. i.e., tocopherol deficiency causes sterility in males.

Question 89.
What is the name of vitamin ‘C’? Deficiency of vitamin ‘C’ causes which disease?
Answer:
The chemical name of vitamin ‘C’ is Ascorbic acid. Its deficiency results in Scurvy disease.

Question 90.
What are saprophytes?
Answer:
Saprophytes: Saprophytes are the organisms which obtain their food from dead plants, dead and decaying animal bodies and other organic matter. Eg: Fungi, many bacteria.

Question 91.
What is peristaltic movement?
Answer:
Peristaltic movement: The muscles present in the wall of oesophagus rhythmically contracts and relaxes. This produces an wave like movement known as a peristaltic movement.

Question 92.
Name the intestinal enzymes present in small intestine and what are their functions.
Answer:
Peptidases and sucrases are the enzymes present in the intestinal juice. Peptidases converts peptides to amino acids. Sucrase converts sucrose (cane sugar) into glucose.

Question 93.
Name the parts of small intestine.
Answer:
The anterior part of small intestine is called the duodenum, the middle part is the jejunum and the posterior part is called the ileum.

Question 94.
What is the enzyme present only in children?
Answer:
Renin is the enzyme present only in children. It helps in curdling of milk.

Question 95.
How many types of teeth are present in our mouth?
Answer:
Four types of teeth are present in our mouth. They are incisors, canine, premolars and molars.

Question 96.
What is the use of tongue?
Answer:
Tongue is useful for mixing and pushing the food in between teeth and helps to push into oesophagus.

Question 97.
What was the opinion of C.B. Van Neil on the equation for photosynthesis?
Answer:
For each molecule of carbohydrate formed, one molecule of water and one molecule of oxygen is also produced.

Question 98.
“Plants are capable of surviving under a range of situations.” How do you support this statement?
Answer:

1. Plants are capable of surviving under a range of situations.
2. They survive from very hot, dry and brightly lighted conditions to wet, humid and dimly lighted ones.
3. The requirement of light and other factors varies from one plant to other.

Question 99.
From where do we get energy to do work?
Answer:
We get energy to do work from the food we eat.

Question 100.
What did Priestly hypothesize on the experiment he conducted on the role of air in the growth of plants?
Answer:
Priestly hypothesized that plants restore to the air whatever breathing animals and burning candles remove.

Question 101.
How does gaseous exchange occur in plants?
Answer:
Gaseous exchange occurs in plants through the stomata present in leaves and also through the lenticels present on stems.

Question 102.
How do the aquatic plants acquire CO₂ to manufacture food?
Answer:
Aquatic plants utilizes or absorbs the carbon dioxide dissolved in water in the form of bicarbonates to manufacture food.

Question 103.
In the experiment to prove that starch is produced during photosynthesis. Why do we boil the leaf in alcohol?
Answer:
We boil the leaf in alcohol to remove all the chlorophyll present in the leaf. The leaf turns to white in colour.

Question 104.
In the experiment to show that sunlight is necessary for photosynthesis, why do we immerse leaf in boiling water?
Answer:

1. Immersing leaf in boiling water will breakdown the cell membranes of leaf cells.
2. It makes the leaf more permeable to iodine solution, so that it can reach the starch present inside the leaf cells.

Question 105.
Why do we have to destarch the leaf before conducting experiment on photosynthesis?
Answer:
This is because if starch is present it will interfere with the result of the experiment.

Question 106.
Why is a water bath used for heating alcohol in which leaf is kept inside the beaker for testing the presence of starch?
Answer:
A water bath is used here for heating alcohol because alcohol is a highly inflammable liquid. So if alcohol is heated directly over a flame, then it will catch fire at once.

Question 107.
What are the reasons for vomiting?
Answer:
Causes for vomiting :

1. Overeating especially when the food contain a high proportion of fat.
2. When we eat something very indigestible or poisonous.

Question 108.
Why do we feel bilious or liverish?
Answer:
We feel bilious or liverish because of having eaten rich meals for several days.

10th Class Biology 1st Lesson Nutrition 2 Marks Important Questions and Answers

Question 1.
Vitamin A, D, E and K are fat soluble vitamins. Write the deficiency diseases and resources of these vitamins in a tabular form.
Answer:

Question 2.
A doctor visited your school to check up the health of school children. What kind of questions do you ask to know about the pancreas?
Answer:

1. Where is pancreas located?
2. Why pancreas is called as mixed gland?
3. What are the hormones released by the pancreas?
4. What are the enzymes released by the pancreas?
5. What are the disorders occur if pancreas does not work properly?
6. What is the role of pancreas in digestion?

Question 3.
Look at the following equation and answer the questions:
Fats + Bile → Fat globules
a) What is the name of that reaction?
b) Which gland plays major role in this reaction?
Answer:
a) The name of the reaction is Emulsification.
b) The gland LIVER plays major role in this reaction.

Question 4.

We know that food is the main source to maintain biological processes in a perfect manner. Our diet should be a balanced one which contains proper amount of carbohydrates, proteins, vitamins, mineral salts and fats. Two third of world population is affected by food related diseases. Some of them are suffering by consuming high calorific food. Most of them are facing various diseases due to lack of balanced diet. Eating of food that does not have one or more than one nutrients in required amount is known as malnutrition. Poor health, will full starvation, lack of awareness of nutritional habits, socio-economic factors are all the reasons of malnutrition.

i) Define Balanced diet.
ii) What is malnutrition and what could be the possible reasons for it?
Answer:
i) The food containing proper amount of carbohydrates, proteins, vitamins, mineral salts and fats is known as “balanced diet”.

ii) Eating of food that does not have one or more than one nutrients in required amounts is known as “malnutrition”.
Poor health, starvation, lack of awareness of nutritional habits, socio-economic factors are all reasons for malnutrition.

Question 5.
What questions do you ask your teacher to know about the obesity and its consequences?
Answer:

1. What are the reasons for Obesity?
2. How to reduce the body weight?
3. What are the consequences of obesity?
4. What type of food you suggest to people suffering from obesity?

Question 6.
Prepare four questions for the Gastro-enterologist to know the problems that occur in the digestive system.
Answer:

1. Why do the people suffer from indigestion problems?
2. Why do we get vomitings?
3. Why do we get belching?
4. Why do we get ulcers in stomach?
5. What is acidity?

Question 7.
Balance the following equation. Write what you have received through this equation.

Answer:

1. This equation represents the process of photosynthesis. For the photosynthesis to occur, four factors are required. They are carbon dioxide, water, light and chlorophyll.
2. 6 molecules of carbon dioxide and 12 molecules of water in the presence of sun light and chlorophyll forms 1 molecule of glucose, 6 molecules of water and 6 molecules of oxygen.

Question 8.
Pregnant ladies are advised to eat leafy vegetables and take folic acid pills. Why?
Answer:

1. Folic acid is the part of the B – a complex family of vitamins.
2. Dark green leafy vegetables are a good source of folic acid.
3. Folic acid is often prescribed for pregnant women because it is essential for the normal development of the brain and spinal cord of the foetus.
4. It also help in protection against birth defects.
5. It also required for the synthesis of nucleic acids DNA and RNA.
   Hence pregnant ladies are advised to eat leafy vegetables and take folic acid pills.

Question 9.
You want to know about intestinal juice from your nearby doctor. Which questions do you ask him?
Answer:

1. Which part of the small intestine secrete intestinal juice?
2. Intestinal juice contains which enzymes?
3. Intestinal juice converts peptids into?
4. Sucrose present in intestinal juice converts sucrose to?
5. Digestion of which nutrient resumes in small intestine?
6. Which digestive juice involved in the complete digestion of food?

Question 10.
Photosynthesis process provides food for all organisms. It mainly takes place by two phases. Light reaction is first phase.
H₂O → H + OH
Above equation in light reaction shows what?
Answer:

1. The first phase of photosynthesis is light reaction. It occurs in grana of the chloroplast.
2. During this phase light-activated chlorophyll molecule splits water molecule into Hydrogen (H⁺) and Hydroxyl ions (OH^–)
3. This reaction is known as photolysis of water which means splitting by light (photo means light, lysis means breaking). This was discovered by Hill. Hence it is also called Hill’s reaction.

Question 11.
Write names of the given sentences.
i) Organelle in which photosynthesis occurs.
Answer:
Chloroplast

ii) Life process in which complex food is converted into simple substances.
Answer:
Digestive system

iii) The part after large intestine in digestive tract.
Answer:
Anus

iv) Deficiency of Vitamin “K” causing disease.
Answer:
Delay in blood clotting.

Question 12.
Write about the nutrition in Amoeba. (OR)
Observe the below given organism and write its name. How nutrition occurs in this organism ?
Answer:

1. The mode of nutrition in Amoeba is holozoic nutrition.
2. Amoeba takes in food using temporary finger like extensions called pseudopodia.
3. These pseudopodia fuse over the food particle forming food vacuole.
4. Inside the food vacuole, complex substances are broken down into simple ones which then diffuse into the cytoplasm.
5. The remaining undigested material is moved to the surface of the cell and thrown out.

Question 13.
Write a short note on heterotrophic nutrition.
Answer:

1. Heterotrophic nutrition is that mode of nutrition in which an organism cannot make its own food from simple inorganic materials like CO₂ and water and depends on other organisms for food.
2. Examples are all animals, most bacteria and fungi.
3. Heterotrophs depend on others for their food requirement.

Question 14.
How is a more serious form of indigestion caused?
Answer:

1. A more serious form of indigestion is caused by stomach and duodenal ulcers.
2. These conditions occur more often in people who may be described as hurried or worried.
3. The ulcers occur more often in busy people who get into the habit of hurrying over meals and rushing from one activity to another without sufficient rest.

Question 15.
What is parasitic nutrition? Write briefly about it.
Answer:

1. Parasitic nutrition is that nutrition in which an organism derives its food from the body of another living organism without killing it.
2. The organism which obtains the food is called a parasite and the organism from whose body food is obtained is called the host.
3. A parasite usually harms the host.
4. The host may be a plant or an animal.
5. Parasitic mode of nutrition is seen in several fungi, bacteria, a few plants like cuscuta and animals like plasmodium.

Question 16.
Write about holozoic mode of nutrition.
(OR)
What is holozoic nutrition?
Answer:

1. Holozoic nutrition means feeding on solid food.
2. Holozoic nutrition is that nutrition in which an organism takes the complex organic food materials into its body by the process of ingestion.
3. The ingested food is digested and then absorbed into the body cells of the organism.
4. The undigested and unabsorbed part of the food is thrown out of the body of the
   organism by the process of ingestion.
5. The human beings and most of the animals have a holozoic mode of nutritions.

Question 17.
Briefly explain about saprophytic nutrition.
(OR)
What are saprophytes? How does nutrition occur in them?
Answer:

1. Saprophytic nutrition is that nutrition in which an organism obtain its food from dead and decaying plant and animal bodies.
2. Organisms having saprophytic mode of nutrition are called saprophytes.
3. Fungi and bacteria are saprophytes.
4. The saprophytes breakdown the complex organic molecules present in dead and decaying matter and convert them into simple substances outside their body.
5. These simple substances are then absorbed by saprophytes as their food.

Question 18.
What is malnutrition? What are the reasons for it? What are the different types of malnutrition?
Answer:

1. Eating of food that does not have one or more than one nutrients in required amount is known as malnutrition.
2. Reasons for malnutrition: Poor health, will-full starvation, lack of awareness of nutritional habits, socio economic factors are all the reasons for malnutrition.
3. Different types of Malnutrition:
   1. Calorie malnutrition,
   2. Protein malnutrition and
   3. Protein calorie malnutrition.

Question 19.
Write a short note on obesity. (OR)
What are the ill effects of obesity?
Answer:

1. Obesity is due to over eating and excess of energy intake.
2. It is a big health hazard. Obese children when grow, they will be target of many diseases.
3. Obesity children usually suffer from diabetes, cardiovascular, renal, gall bladder problems.
4. Eating junk foods and other food habits lead to obesity.

10th Class Biology 1st Lesson Nutrition 4 Marks Important Questions and Answers

Question 1.
Answer the following questions by observing the diagram showing the experiment:
a) What will you prove by this experiment?
Answer:
By this experiment we will going to prove oxygen is released during photosynthesis.

b) What apparatus do you use in this experiment?
Answer:

1. Beaker
2. Test-tube
3. Funnel
4. Hydrilla Plant
5. Burning splinter.

c) What would be the results if the experiment is done in shadow?
Answer:
If we conduct this experiment in shadow no change in the water level of the Test-tube. No photosynthesis occur. No air bubbles are form.

d) What will you do to obtain result from the experiment?
Answer:
If the burning splinter is kept near the mouth of test tube, burns brightly.

Question 2.
Answer the following questions by observing the diagram showing the experiment.
a) What will you prove by this experiment?
Answer:
Carbon dioxide (CO₂) is necessary for the photosynthesis.

b) What apparatus do you use in this experiment?
Answer:
Wide mouthed bottle, split cork, KOH solution, Iodine, Potted plant.

c) Why do we use KOH solution in this experiment?
Answer:
KOH is used for the absorption of CO₂ in the bottle.

d) Why did we study two leaves in this experiment?
Answer:
We should test two leaves of which one must be having the availability of CO₂ and other must not be having the availability of CO₂ to prove that CO₂ is essential for photosynthesis.

Question 3.
Describe an experiment conducted by Joseph Priestley which revealed the essential role of air in the growth of green plants.
(OR)
What is the role of air in the growth of green plants?
(OR)
Write the experiment of bell jar and pudina plant, performed by Priestley to prove that air plays key role in Photosynthesis.
Answer:

1. Joseph Priestley in 1770 performed a series of experiments that revealed the essential role of air in the growth of green plants.
2. Priestley discovered oxygen in 1774.
3. Priestley observed that a candle burning in a closed space, a bell jar, soon gets extinguished.
4. Similarly, a mouse would soon suffocate in a closed space of the bell jar.
5. He concluded that a burning candle or an animal, both somehow, damage air.
6. But when he placed a mint plant in the same bell jars, he found that the mouse stayed alive and the candle when lighted from outside continued burning in the presence of the mint plant.
7. Priestly hypothesized as plants restore to the air whatever breathing animals and burning candles remove.

Question 4.
B₁, B₂, B₃, A, C, D, E, K are the symbols of vitamins. Classify these vitamins based on solubility and diseases due to vitamins deficiency.

Answer:

Question 5.
During Photosynthesis, several events occurs in the chloroplast. Explain the light dependent reactions.
(OR)
Write the mechanism of light dependent reactions in Photosynthesis.
Answer:
Light reaction takes place in grana thylakoids of chloroplast.
The following events occurs in the light dependent reaction.
1. Step -1: The chlorophyll on exposure to light energy becomes activated by absorbing photons of light energy.
2. Step – II: The activated energy is used in splitting the water molecule into hydrogen (H⁺) and hydroxyl ion (OH^–). This reaction is known as photolysis or Hill’s reaction.
H₂O → H + OH
3. Step – III : Water (H₂O) and oxygen (O₂) are produced by the OH^– ions through a series of reaction.
4. Step – IV: H⁺ ions are involved in the synthesis of ATP and NADPH which are the end products of light reaction. These are called assimilatory powers.

Question 6.
You might have conducted and experiment in your school laboratory to prove that CO₂ is essential for Photosynthesis. Raju, who is in 9th class, wanted to perform the same experiment. He had some doubts regarding this experiment. Clarify them.
i) Prior to the experiment, the potted plant was kept in a dark room for a week. Why?
Answer:
To destarch the plant.

ii) KOH pellets were kept in the glass jar. Why?
Answer:
To absorb CO₂

iii) Write the apparatus used to perform this experiment.
Answer:
Potted plant, wide mouthed transparent bottle, splitted cork.

iv) What will be the result, if the same experiment is conducted in dark?
Answer:
Photosynthesis does not take place.

Question 7.
Write the differences between light and dark reactions of photosynthesis.
Answer:

Question 8.
Draw a neat labelled diagram of internal structure of leaf. Which mesophyll cells of the leaf consist of chloroplast?
Answer:
Palisade parenchyma and spongy parenchyma consist of chloroplast.

Question 9.
Keep a plant for a week in the dark. Then insert one leaf of this plant into a transparent bottle containing potassium hydroxide solution. Keep the plant in sunlight. Test the leaf in the bottle and any other leaf of the plant with Iodine, after a few hours.
i) What is the aim of this experiment?
ii) What will be observed in the leaf kept in the bottle and a leaf from the plant?
iii) Why was the plant kept in the dark first and then in the sunlight?
Answer:
i) To prove that CO₂ is necessary for photosynthesis.
ii) The leaf part kept in the bottle does not show colour change in iodine test, whereas the leaf exposed to air turns bluish-black in the iodine test.
iii) To remove starch from leaves (destarching).

Question 10.
Analyse the following information and answer the questions.

i) Which vitamins deficiency causes diseases related to bones?
Answer:
Calciferol – Vitamin – D, deficiency causes diseases related to bones,

ii) Which vitamins we get by eating fruits?
Answer:
Retinol – Vitamin – A, and Tocoferol – Vitamin – E we get them by eating fruits,

iii) Which vitamin deficiency causes Paralysis? To prevent iii), what type of food we have to eat?
Answer:
Paralysis is caused by the Vitamin (B}) Thiamine deficiency.
To prevent this disease, we have to eat cereals, oil seeds, vegetables, milk, meat, fish and eggs.

iv) To avoid vitamin deficiency diseases, what type of food we have to eat?
Answer:
To avoid vitamin deficiency diseases, we have to take proper diet.
Our diet should be a balanced one which contains proper amount of carbohydrates, proteins, vitamins, mineral salts and fats.

Question 11.
What are fat soluble vitamins? Explain the deficiency diseases due to deficiency of fat soluble vitamins and their symptoms.
Answer:
Fat soluble vitamins :

Question 12.
Read the table and answer the following questions.

i) Name the anti-sterility vitamin from the above table.
Answer:
Tocoferol (Vitamin E) is the anti – sterility vitamin.

ii) WTiich vitamin deficiency that causes the gums bleeding?
Answer:
Ascorbic acid (Vitamin C) deficiency causes the gums bleeding.

iii) Name the fat soluble vitamins from the above.
Answer:
Retinol (Vitamin A), Tocoferol (Vitamin E), Phylloquinone (Vitamin K) are fat soluble vitamins.

iv) Name the symptoms that appear due to deficiency of vitamin K.
Answer:
Delay in blood clotting, over bleeding are the symptoms appear due to deficiency of vitamin K.

Question 13.
Mention different modes of nutrition. Explain the mode of nutrition in Cuscuta.
Answer:
There are different modes of nutrition
Parasitic Nutrition in Cuscuta :

1. Cuscuta plant is the best example for parasitic nutrition.
2. It contains no chlorophyll and has root like structures called haustoria.
3. With the help of haustoria, cuscuta absorbs nutrients from it’s host plant.
4. As cuscuta grows on the host plants, its roots gradually degenerated and it establishes firmly on the host plant.
5. Meanwhile, the root rots away after stem contact has been made with a host plant.
6. As dodder grows, it sends out new haustoria and establishes itself very firmly on the host plant.
7. After growing in a few spirals around one host shoot, the dodder finds its way to another.
8. It continues to twine and branch until it resembles a fine densley tangled web of thin stems enveloping the host plant.

Question 14.
Is the malnutrition reason for diseases? Why? Write any of such disease and its characters.
Answer:

1. Yes, malnutrition is the reason for occurrance of diseases.
2. Malnutrition is eating of food that does not have one or more than one nutrients in required amount.
3. This results in scarcity of nutrients for the proper growth and health of the individual.
4. Kwashiorkor disease occurs in children due to the deficiency of proteins in the diet.
5. Characteristic features of kwashiorkor disease :
   1. Body parts becomes swollen due to accumulation of water in the intercellular spaces.
   2. Very poor muscle development, swollen legs, fluffy face, difficult to eat, diarrhoea, dry skin are the symptoms of Kwashiorkor disease.
   3. The child becomes lethargic and shows little interest in its surroundings or in playing and learning.

Question 15.
Which issues do you take into consideration to tell that plants play a key role in animals nutrition?
Answer:

1. Plants play a very important role in nutrition of animals. Actually plants are the producers whereas animals are dependent on plants for their nutrition.
2. Many plants or plants parts are eaten as food. There are around 2000 plant species which are cultivated for food. Nutrients like carbohydrates, proteins, fats, vitamins and minerals are available from these plants.
3. Seeds of plants are good sources of food for animals including humans because they contain many healthful fats.
4. Infact majority of the food consumed by human beings are seed based food. Edible seeds include cereals like wheat, rice, maize etc. and legumes like pea, groundnut and nuts.
5. Oil seeds are often pressed to produce rich oils like sunflower, groundnut, sesame etc.
6. Seeds are typically high in unsaturated fats and considered as a health food.
7. Fruits are the ripened ovaries of plants including the seeds within. Many plants and animals have coevolved such that the fruits of the former are an attractive food source to the later.
8. Vegetables are a second type of plant matter that is commonly eaten as food.
9. Hence all the nutrients required by animals are available to the animals from plants. Hence plants are playing an important role in nutrition of animals including human beings.

Question 16.
Give examples for the vitamin deficiency diseases.
Answer:

Question 17.
We know that by taking different types of food materials we will get vitamins. For this what changes shall we take in our food habits?
Answer:

1. Eating of rice polished only for one time gives us vitamin thiamine in abundant amount.
2. We should eat balanced food containing nutrients in equal quantities.
3. Fresh leafy vegetables are rich source of vitamins Riboflavin, Folic acid and Vitamin ‘C’. So our diet should contain these leafy vegetables.
4. Sufficient amount of non-vegetarian foods like meat, poultry, fish, kidney and liver should present in our food.
5. Eating fresh fruits also add number of vitamins to our body.
6. Whole cereals like wheat, rice provide number of vitamins to our body. So we shall eat required quantities of cereals in our food.

Question 18.
Describe what disaster occurs on earth, if photosynthesis life process stops.
Answer:

1. Plants are the universal food providers. If they stop photosynthesis all the animals would die due to starvation.
2. Plants release oxygen during photosynthesis. It is essential for survival of all living beings. If photosynthesis does not take place, there would be no oxygen on the earth and no chance of survival of life on this planet.
3. plants utilise CO₂ for photosynthesis. If it does not occur, CO₂ utilisation is stopped and hence increase in the levels of CO₂ This leads to global warming.

Question 19.
Describe the experiment conducted by Jan Baptist Von Helmont and discuss his results in the growth of plant body mass.
(OR)
How is water required for the growth of plant body mass?
Answer:

1. In the year 1648 a Belgian scientist Jan Baptist Von Helmont conducted an experiment that continued for five years.
2. He took a small willow tree and planted it in a large pot of soil.
3. Before he did the experiment he carefully measured the mass of the dry soil and mass of the tree.
4. He covered the soil with a lid so that nothing could fall on to the surface of the soil and add to its mass.
5. There were holes in the lid so that the tree could grow out of the soil and so that air and water could reach the roots.
6. Von Helmont left the tree for five years giving it only rain water to drink.
7. At the end of five years he measured the mass of the tree and the mass of the dry soil for a second time.
8. The results of this experiment are shown below.
   

   Mass (Kg)
   	At start	After five years	Change in mass (Kg)
   Tree	2.27	76.74	74.47
   Drv soil	90.72	90.66	0.06

9. This experiment changed the belief of hundreds of years. This is because Von Helmont arrived at a result that
   a) The substances needed for the growth of a plant do not come from the soil only.
   b) The plant grow because of the water it gets.

Question 20.
Write an account on the mechanism of dark reaction.
(OR)
Write an account on carbon fixation.
(OR)
Briefly explain the Melvin Calvin cycle.
Answer:

1. The reactions of photosynthesis which do not require light energy are called dark reactions. These reactions occur both in presence and absence of light.
2. Dark reactions occur in the stroma of the chloroplast and these were discovered by American scientist Melvin Calvin.
3. In the first reaction carbon dioxide is accepted by Ribulose 1 – 5 biphosphate, a five carbon sugar to form hexose sugar.
4. It is an unstable compound so it breaks down into two molecules of three carbon compounds called phospho glyceric acid (PGA).
5. 
6. Phospho glyceric acid undergoes a series of reactions and is converted to glyceral- dehyde – 3 phosphate. NADPH and ATP produced in light reactions are used up at this stage.
   
7. Two molecules of glyceraldehyde – 3 phosphate combine together to form glucose molecule.
8. In the end glucose is converted into starch.
   Summary reaction :
   

Question 21.
Describe the buccal cavity of human beings.
(OR)
How is food masticated in buccal cavity?
Answer:

1. The cavity or space in the mouth is called oral cavity or buccal cavity.
2. Teeth, tongue and openings of three salivary glands are present in buccal cavity
3. Incisors, canines, premolars and molars are the different types of teeth present in the mouth.
4. Tongue is muscular and pushes the food on to the teeth during mastication. It also helps in swallowing the food into oesophagus.
5. Three pairs of salivary glands present in the buccal cavity are parotid, sub-lingual and sub-maxillary glands.
6. Parotid glands are present near the ears. The other two pairs of glands open below the tongue through ducts.

Question 22.
What is indigestion? How can we avoid indigestion?
Answer:
Indigestion: Indigestion is a general term when there is difficulty in digesting food. Healthy people can usually avoid problems related to indigestion by:

1. Having simple, well balanced meals.
2. Eating them in a leisurely manner. ,
3. Thoroughly masticating the food.
4. Avoiding taking violent excercises soon after eating food.
5. Drinking plenty of water and having regular bowel movements.

Question 23.
What are vitamins? Why they are called essential nutrients? What is their role in the human body?
Answer:

1. Vitamins are organic substances.
2. They are micro – nutrients required in small quantities.
3. Actually vitamins are not synthesised in the body and therefore they are essential nutrients.
4. Though our body cannot synthesis vitamins we do not generally suffer from vitamin deficiency disease.
5. This is because of two sources of vitamins for our body. Diet is the primary source.
6. In addition, bacteria present in the intestine synthesis vitamins and supply them to us
7. By themselves vitamins cannot generate any energy or carryout any chemical reaction.
8. In the body vitamins combine with some of the enzymes and make the enzymes active.
9. In the absence of vitamins, enzymes become inactive and cannot catalyse the reactions.
10. Vitamins are normally present in all types of natural foods – milk, meat, fruits and vegetables.
11. Vitamins are of two types:
    1. Water soluble vitamins eg: B complex and Vitamin C and
    2. Fat soluble vitamins eg: A, D, E and K.

Question 24.
Give an account of water soluble vitamins, their occurrence, deficiency diseases and symptoms.
Answer:
Vitamins, available sources and deficiency diseases:

Question 25.
a) What apparatus do you use during the conduction of the experiment?
b) Before conducting the experiment, why do you keep the potted plant in dark place for a week?
c) What test do you conduct to know the formation of carbohydrates in leaves?
d) During the test, which part of the leaf turns into blue and which part doesn’t? Why?
Answer:
a) Potted plant, Light screen, Iodine solution, Petridish, Black paper.
b) To destarch the leaves.
c) Iodine Test
d) The part of the leaf exposed to light turn into blue. Unexposed part does not turn into blue.
Reason: Photosynthesis occurs only in the presence of sunlight. The unexposed part does not receive the sunlight.

Question 26.
Draw the diagram of equipment arrangement in Hydrilla experiment. You did to prove that oxygen releases in photosynthesis. Write the reasons why test tube is placed upside down on funnel.
Answer:
Reasons for placing the test tube upside down on funnel:

1. To count the number of bubbles coming out of the hydrilla twigs per minute during photosynthesis.
2. To collect sufficient amount of oxygen at the end of the test tube so that it can be tested with glowing splinter.
3. Amount of oxygen produced in the test tube can be measured by the displacement of water within the test tube.

Question 27.
Describe the internal structure of the leaf.
(OR)
How is the internal structure of leaf modified to prepare starch through the process of photosynthesis?
Answer:

1. A transverse section of a typical leaf shows that it is covered on both sides by epidermis. Epidermal layers are covered on both sides by cuticle.
2. Lower epidermis is interrupted by a large number of openings called stomata. The central opening is called stoma.
   
3. Each stoma is surrounded by two kidney shaped cells called Guard cells.
4. Stomata regulate the exchange of gases and loss of water vapour from the leaves.
5. Mesophyll is the tissue present between two epidermal layers. Upper mesophyll tissue is called palisade parenchyma and lower tissue is known as spongy parenchyma.
6. The cells in the palisade parenchyma are long elongated arranged in rows.
7. The cells in the spongy parenchyma are irregularly arranged cells with large inter cellular spaces.
8. More number of chloroplasts are present in palisade parenchyma than the spongy parenchyma.
9. In the midrib and veins vascular bundles are present with phloem located towards the lower side and xylem towards the upper side.

Question 28.
Write about the parasitic nutrition in cuscuta plant.
Answer:

1. Dodder (genus cuscuta) is a leafless, twining, parasitic plant belongs to family convolvulaceae.
2. The dodder contains no chlorophyll and instead absorbs food through haustoria.
   
3. The dodder’s seed germinates, forming an anchoring root, and then sends up a slender stem that grows in a spiral fashion until it reaches a host plant.
4. It then twines around the stem of the host plant and throws out haustoria, which penetrate it.
5. Water is drawn through the haustoria from the host plant’s stem and xylem, and nutrients are drawn from its phloem.
6. Meanwhile, the root rots away after stem contact has been made with a host plant.
7. As the dodder grows, it sends out new haustoria and establishes itself very firmly on the host plant.
8. After growing in a few spirals around one host shoot, the dodder finds its way to another and it continues to twine and branch until it resembles a fine densley tangled web of thin stems enveloping the host plant.

Question 29.
Describe the digestion of food materials in alimentary canal with the help of a diagram.
(OR)
How is the food digested in your body?
Answer:

1. The alimentary canal is basically a long tube extending from the mouth to the anus.
2. Food is masticated by our teeth in the mouth and mixed with saliva to make it slippery and wet.
3. Saliva which contains amylase helps in the breakdown of carbohydrates into simple ones.
   
4. The soft food mixed with saliva passes through oesophagus or food pipe by wave like movements called peristaltic movements to the stomach.
5. The gastric glands in the stomach secrete gastric juice that contains hydrochloric acid, protein digesting enzyme pepsin and mucus.
6. Partially digested food chyme is released in small amounts by sphincter muscles reach small intestine.
7. Bile juice secreted by liver and pancreatic juice secreted by the pancreas release into the duodenum of small intestine.
8. Emulsification of fats is done by bile juice. Pancreatic juice contains enzyme trypsin for carrying on the process of digestion of proteins and lipase for fats.
9. Complete digestion of carbohydrates, fats and proteins takes place in the small intestine by intestinal juice.
10. Finger-like projections present in the walls of small intestine are called villi. They absorb the digested food into the blood.
11. Rest of the food is sent into the large intestine where most of the water present in it is absorbed from the food.
12. This material is then expelled through the anus which is the last part of the alimentary canal.

Question 30.
Draw a flow chart of human digestive system.
Answer:

Question 31.
Write briefly about nutrition in paramoecium. (OR)
Explain the nutrition process in paramoecium with the help of diagrams.
Answer:
Paramoecium :

1. Paramoecium is a unicellular aquatic organism.
2. The paramoecium has thin, hair like cilia all over its body.
   
3. The cilia move back and forth rapidly in water.
4. When the cilia is present around, the mouth region of paramoecium move, back and forth. They sweep the food particles present in water into the mouth of paramoecium.
   
5. This is the first step in the nutrition of paramoecium which is called ingestion and is followed by digestion, absorption, assimilation and egestion.

Question 32.
Describe the digestion of food in the stomach. (OR)
How is the food digested in your stomach ?
Answer:

1. The stomach is a large organ which expands when food enters it.
2. The muscular walls of the stomach help in mixing the food thoroughly with more digestive juices.
   
3. The gastric glands present in the wall of the stomach secrete gastric juice which contains hydrochloric acid, pepsin and mucus.
4. The hydrochloric acid facilitates the action of the enzyme pepsin and also kills the germs present in the food.
5. The enzyme pepsin digests proteins and mucus protects the inner lining of the stomach from the action of the acid under normal conditions.

Question 33.
Describe the digestion of food in the small intestine. (OR)
What are the changes that you see during the digestion of food in small intenstine?
(OR)
Small intestine is a long coiled tube. How the food is digested in small intestine of human being?
Answer:

1. The small intestine is the longest part of the alimentary canal.
2. It is the site of the complete digestion of carbohydrates, proteins and fats.
   
3. It receives the secretion of liver and pancreas for this purpose.
4. These juices make the internal condition of the intestine gradually to a basic or alkaline one.
5. Bile juice secreted by liver breaks down fats into small globules like forms. This process is called emulsification.
6. Pancreatic juice contains enzymes like trypsin for carrying on the process of digestion of proteins and lipase for fats.
7. Walls of the small intestine secrete intestinal juice. This is also known as succus entericus.
8. The intestinal juice consists of enzymes like enterokinase, peptidase, lipase, sucrase, nucleotidase, nucleosidase etc.
9. Enzymes present in the intestine completely digest the partially digested food.
10. Following digestive processes take place in the intestine.
    a) Peptidases convert peptides into amino adds.
    b) Intestinal lipase completely digest fats into fatty acids and glycerol.
    c) Enzymes sucrase, maltase, lactase hydrolyse sucrose, maltose and lactose respectively converting them into glucose.
    d) Nucleotidase and nucleosidase complete the digestion of nucleic acids.
11. The end products of digestion are absorbed in the intestine.

Question 34.
What are the health aspects of the alimentary canal?
Answer:

1. The human alimentary canal usually functions remarkably well considering how badly we treat it on occasions.
2. Vomiting is the body’s method of ridding itself unwanted or harmful substances from the stomach.
3. There are many causes of vomiting, but one of the most common is over eating, especially when the food contains a high proportion of fat.
   
4. The liver is unable to cope with the excessive fat and we get a feeling of nausea and sometime headache.
5. Indigestion is a general term used when there is difficulty in digesting food.
6. A more serious form of indigestion is caused by stomach and duodenal ulcers. These conditions occur more often in people who may be described as hurried or worried.
7. Those who are able to relax, who are not continually tensed up, and who live at a slower pace, seldom get ulcers.
8. For good health it is necessary to empty the bowels regularly.
9. If the food residues remain in the colon for too long, the bacteria present have more time to produce harmful substances which may be absorbed by the blood.
10. Constipation can often be avoided by having plenty of roughage in the diet.

AP State Board Syllabus AP SSC 10th Class Physics Solutions Chapter 1 Heat Textbook Questions and Answers.

AP State Syllabus SSC 10th Class Physics Solutions 1st Lesson Heat

10th Class Physics 1st Lesson Heat Textbook Questions and Answers

Improve your learning

Question 1.
What would be the final temperature of a mixture of 50 g of water at 20° C temperature and 50 g of water at 40° C temperature? (AS1)
Answer:
In CGS system :
Mass m₁ = 50 g
Higher temperature = T₁ = 40° C
Mass m₂ = 50 g
Lower temperature = T₂ = 20° C

Question 2.
Explain, why dogs pant during hot summer days using the concept of evaporation. (AS1)
(OR)
How do dogs cool their body? Explain by using the process of evaporation.
Answer:

• Dogs pant during hot summer days and get their body cooled. This cooling effect is due to evaporation.
• Evaporation is a surface phenomenon. Temperature of a system falls during evaporation.
• During summer the temperature in the human body increases.
• The temperature of the skin becomes higher and the water in the sweat glands starts evaporating. Since evaporation is a cooling process human body becomes cool.
• Dogs don’t have sweat glands. Their body is covered with hair. They have sweat glands only in their feet.
• So by panting the water on the tongue undergoes evaporation resulting in the cooling of the dog’s body.

Question 3.
Why do we get dew on the surface of a cold soft drink bottle kept in open air? (AS1)
(OR)
Raju observed small droplets of water outside a cold soft drink bottle kept in open air. What is the reason for the formation of droplets?
Answer:

• When cold soft drink bottle is kept in open air, the temperature of surrounding air is higher than the temperature of cold drink bottle.
• Air contains molecules in the form of vapour.
• During the motion of water molecules in air strike the surface of cold drink bottle.
• Then the molecules of air lose their kinetic energy which leads to lower the temperature and they convert into droplets.
• So dew is formed on the surface of cold soft drink bottle.

Question 4.
Write the differences between evaporation and boiling. (AS1)
(OR)
Sita observed decrease in quantity of spirit kept in a vessel placed in open air. Whereas Ramu observed formation of bubbles on a water surface when it is heated. What are those two processes? Distinguish between those two processes.
Answer:

Question 5.
Does the surrounding air become warm or cool when vapour phase of H₂O condenses? Explain. (AS1)
Answer:

• Gases have more higher energy than liquids and solids.
• When vapour condenses, it changes from gas to liquid.
• Therefore there is a drop in energy.
• This energy has to go (somewhere) to the surroundings.
• So surrounding air becomes warm when vapour phase of H20 condenses.

Question 6.
Answer these. (AS1)
a) How much energy is transferred when 1 gm of boiling water at 100°C condenses to water at 100°C?
Answer:
CGS system :
Mass of water = m = 1 gm
Latent heat of vapourisation = 540 cal/gm.
The amount of heat energy released when 1 gm of boiling water at 100°C condenses to water at 100°C
Q = mL_vapour = 1 × 540 = 540 cal.

(OR)

In SI system :
Mass of water = m = 1 gm = 1 × 10^-3 kg
Latent heat of vapourisation = 540 cal/gm.
The amount of heat energy released when 1 gm of boiling water at 100°C condenses to water at 100°C
Q = mL_vapour – 1 × 540 = 540 cal.
In SI, Q = 540 × 4.18 = 2257 J.

b) How much energy is transferred when 1 gm of boiling water at 100° C cools to water 0° C?
Answer:
CGS system :
Latent heat of vapourisation = 540 cal/gm
The amount of heat energy released when 1 gm of boiling water at 100°C condenses to water at 100 °C. m = 1 gm.
Q₁ = mL_vapour = 1 × 540 = 540 cal.
The specific heat of water = 1 cal/gm-°C
Difference in temperature = 100-0 = 100°C.
The heat released to cool water to 0°C is
Q₂ = mS∆T = 1 × 1 × 100 = 100 cal.
∴ Total energy released = 540 + 100 = 640 cal.

c) How much energy is released or absorbed when 1 gm of water at 0° C freezes to ice at 0° C?
Answer:
In CGS system :
Mass of water = m = 1 gm
Latent heat of fusion of ice (L) = 80 cal/gm
The energy transferred or released when 1 gm of water at 0° C freezes to ice at 0° C.
Q = mL_freeze = 1 × 80 = 80 Cal.

(OR)

In SI system :
Mass of water = m = 1 gm = \(\frac{1}{1000} \mathrm{~kg}\)
Latent heat of fusion = L = 3.36 × 10⁵ J/kg.
Amount of heat released or transferred when lgm of water at 0°C freezes to ice at 0°C.
Q = mL_fusion = \(\frac{1}{1000} \mathrm{~kg}\) × 3.36 × 10⁵ = 3.36 × 10² = 336J.

(OR)

In CGS system :
Mass of water = m = 1 gm
Latent heat of fusion of ice (L) = 80 cal/gm
The energy transferred or released when 1 gm of water at 0° C freezes to ice at 0°C.
Q = mL_freeze = 1 × 80 – 80 cal.
(Or)
In SI system : In SI, Q = 80 × 4.2 [1 cal = 4.2 J]
Q = 1 x 10^-3 × 3.36 × 10⁵ = 3 36 J.

d) How much energy is released or absorbed when 1 gm of steam at 100°C turns to ice at 0°C?
Answer:
In CGS system :
Mass of water = m = 1 gm
Latent heat of vapourisation = L_vapour = 540 cal/gm
Latent heat of fusion of ice = L_fusion = 80 cal
Specific heat of water = S = 1 cal/gm-0°C
Difference in temperature
∆T = 100 – 0 = 100°C.
The energy transferred when 1 gram of steam at 100°C turns to ice at 0°C
Q = mL_vapour + mS∆T + mL_fusion
= 1 × 540 + 1 × 1 × 100 + 1 × 80 = 540 + 100 + 80 = 720 cal.

(OR)

Mass of water = m = 1 gm = \(\frac{1}{1000} \mathrm{~kg}\)
Latent heat of vapourisation = L_vapour = 2.25 × 10⁶ J/kg
Latent heat of fusion = L_fusion = 3.36 × 10⁵ J/kg
Difference in temperature
∆T = 373 – 273 – 100 K.
Specific heat of water = 4180 J/kg-K
The energy transferred when 1 gram of steam at 100° C turns to ice at 0°C =

(OR)

In CGS system :
Conversion : Steam at 100°C → Water at 100°C → Water at 0°C → Ice at 0°C.
Mass of water = m = 1 gm
Latent heat of vapourisation = L_vapour = 540 cal/gm
Latent heat of fusion of ice = L_fusion = 80 cal
Specific heat of water = S = 1 cal/gm-0°C
Difference in temperature
∆T= 100-0 = 100°C.
The energy transferred when 1 gram of steam at 100°C turns to ice at 0°C
Q = mL_vapour + mS∆T + mL_fusion
= 1 × 540 + 1 × 1 × 100 + 1 × 80
= 540 + 100 + 80 = 720 cal. = 720 × 4.18 = 3009.6 J.

Question 7.
Explain the procedure of finding specific heat of solid experimentally. (AS1)
(OR)
Determination of specific heat of solid experimentally.
(OR)
Ravi wanted to prepare solid with high specific heat to use on cooking utensil. What fool does he need to find the specific heat of aluminium and copper? How should he conduct the experiment?
Answer:
Aim : To find the specific heat of given solid.
Apparatus : Calorimeter, thermometer, stirrer, water, steam heater, wooden box and lead shots.

Procedure:

• Measure the mass of the calorimeter with stirrer = m₁ gm
• Fill water one third volume of calorimeter and measure the mass = m₂ gm.
• At this time initial temperature = T₁.
• Mass of the water = m₂ – m₁ gm.
• Take a few lead shots and place them in steam heater and heat up to 100° C. Let this temperature be T₂.
• Transfer the lead shots into calorimeter and measure the final (or) resultant temperature T₃.
• Mass of calorimeter with contents = m₃ gm and mass of lead shots = m₃ – m₂ gm.
• If the specific heats of the calorimeter, lead shots and water are S_c, S_l and S_w respectively, by using method of mixtures we have
  Heat lost by the solid = Heat gained by the calorimeter + water
  
• Knowing the specific heats of calorimeter and water we can calculate specific heat of solid (lead shots).

Question 8.
Convert 20° C into Kelvin scale. (or) Change 20°C into absolute scale. (AS1)
Answer:
T = t°C + 273 = 20 + 273 = 293
⇒ T = 293 K.

Question 9.
Your friend is asked to differentiate between evaporation and boiling. What questions could you ask to make him to know the differences between evaporation and boiling? (AS2)
(OR)
Veena found that the water kept in a pot is cool and Siva observed when water is heated the temperature remains constant for some time until water turns into vapour. What are the processes involved in these two aspects? Ask some questions to understand these aspects.
Answer:
The questions asked by me are :

• How do wet clothes get dried without heating?
• Are boiling and evaporation one and same or different?
• Is there any difference in kinetic energy if it boils?
• Is the temperature the main cause for boiling and evaporation?
• What are the factors which influence evaporation?
• Is boiling temperature for water always 100° C?

Question 10.
What happens to the water when wet clothes dry? (AS3)
Answer:

1. When wet clothes dry, the water present in the clothes is evaporated.
2. So that the process of evaporation causes the wet clothes dry.

Question 11.
Equal amounts of water are kept in a cap and in a dish. Which will evaporate faster? Why? (AS3)
(OR)
Srinu kept. equal amounts of water in a cap and in a dish in open air. What is his observation? Explain the experiment.
Answer:
Aim : To show the evaporation of equal amounts of water in cap and dish.
Apparatus : Cap, dish, water.

Procedure :

• Take equal amounts of water in cap and dish. Keep them in open air for two hours. Now weigh the water in the cap and the dish.
• We can observe that the weight of water in dish is less than that of water in cap.
• This shows that the water in dish has more evaporation than the water in cap.
• It is due to more surface area of dish.
• As the surface area increases rate of evaporation also increases.

Question 12.
Suggest an experiment to prove that rate of evaporation of a liquid depends on its surface area and vapour already present in surrounding air. (AS3)
Answer:
Aim: The rate of evaporation of liquid depends on its surface area and vapour already present in surrounding air.
Apparatus : Two dishes of different surface areas and water.

Procedure :

• Take two dishes of different surface area.
• Pour equal amounts of water in the both dishes.
• Keep aside for two to three hours.
• Observe them after some time.
  Dish with more surface area has less quantity of water than the dish having less surface area. ,
• This shows evaporation increases with increasing of surface area.
• Take two dishes of equal surface area containing water.
• This experiment should be conducted on more humid day and less humid day.
• We will find that evaporation is less on more humid day due to more vapour in the air.
• So evaporation decreases with vapour in the air.

Question 13.
Place a Pyrex funnel with its mouth-down in a sauce pan full of water, in such a way that the stem tube of the funnel is above the water or pointing upward into air. Rest the edge of the bottom portion of the funnel on a nail or on a coin so that water can get under it. Place the pan on a stove and heat it till it begins to boil. Where do the bubbles form first? Why? Can you explain how a natural geyser works using this experience? (AS4)
Answer:

• When Pyrex funnel with its mouth down in a sauce pan then the bubbles formed by the heat energy come from the top of the funnel.
• That is from stem tube.
• This is because of pressure inside mouth of funnel increases rapidly due to increasing of heat energy.
• Pressure inside the funnel rs more than outside the funnel and very high at stem.
• Hence, bubbles come from stem of the funnel and escapes through stem tube with force, like a geyser.

Working of natural geyser by using this experience :

• Geysers are the fountains of hot water coming under the layers of the earth.
• It is a hole with narrow and deep from the bottom of the earth layers.
• It contains water.
• Water heats up due to high temperatures of the inner layers of the earth.
• As by the pressure of water at top layers of the hole, temperature rises, water boils.
• This hot water comes with narrow vent with high pressure, like Lava from the Volcano.

Question 14.
Collect the information about working of natural geyser and prepare a report. (AS4)
Answer:
Natural Geysers :

• Geysers are the fountains of hot water coming under the layers of the earth.
• It is a hole with narrow and deep from the bottom of the earth layers.
  
• It contains water.
• Water heats up due to high temperatures of the inner layers of the earth.
• As by the pressure of water at top layers of the hole, temperature rises, water boils.
• This hot water comes with narrow vent with high pressure, like Lava from the Volcano.
• This looks like a water fountain at the surface of the earth.
  

Question 15.
Assume that heat is being supplied continuously to 2 kg of ice at – 5°C. You know that ice melts at 0°C and boils at 100°C. Continue the heating till it starts boiling. Note the temperature for every minute. Draw a graph between temperature and time using the values you get. What do you understand from the graph ? Write the conclusions. (AS5)
Answer:
Graph between time and temperature from ice melting at 5° C to boils at 100° C.

Understanding from the graph :

• \(\overline{\mathrm{AB}}\) = Ice warms up from – 5°C to 0°C
• \(\overline{\mathrm{BC}}\) = Ice melts at 0°C for a certain time period. So \(\overline{\mathrm{BC}}\) indicates no rising in temperature.
• \(\overline{\mathrm{CD}}\) = Water warms up from 0°C to 100° C, \(\overline{\mathrm{CD}}\) indicates rising in temperature.
• \(\overline{\mathrm{DE}}\) = Water boils at 100° C for a certain time period. So \(\overline{\mathrm{DE}}\) indicates no rising in temperature.

Conclusion :

• The temperature remains same at 0° C until all the ice converted into water. So, 0° C is the melting point of water.
• The temperature remains constant at 100° C until all the water converted into water vapour. So, 100° C is the boiling point of the water.

Question 16.
How do you appreciate the role of the higher specific heat of water in stabilising atmospheric temperature during winter and summer seasons? (AS6)
Answer:

• Due to higher specific heat of water oceans absorb the solar energy for maintaining a relatively constant temperature.
• Oceans absorb large amounts of heat at the equator.
• The oceans moderate the surrounding temperature near the equator.
• Ocean water transports the heat away from the equator to areas closer to the north and south pole.
• This transported heat helps moderate the climate in parts of the Earth that are far from the equator.
• So higher specific heat of water is stabilising atmospheric temperature.
• So we have to extremely appreciate the role of higher specific heat of water to stabilise the atmospheric temperature.

Question 17.
Suppose that 1 / of water is heated for a certain time to rise and its temperature by 2°C. If 2 l of water is heated for the same time, by how much will its temperature. (AS7)
Answer:
Mass of 1 litre of water (m₁) = 1 kg ; ∆T₁ = 2°C
Mass of 2 litres of water (m₂) = 2 kg ; ∆ T₂ = ?
Time duration is same. So same heat is absorbed by water in both the cases
⇒ Q₁ = Q₂
m₁S(∆T₁) = m₂S (∆T₂)

So the rise in temperature for 2 kg of water = 1°C.

Question 18.
What role does specific heat play in keeping a watermelon cool for a long time after removing it from a fridge on a hot day? (AS7)
Answer:

• Generally, watermelon contains large percentage of water.
• Water has high specific heat value than other substances.
• High specific heat substances oppose the increase of temperature. Hence they continuous of the coolingness.
• So watermelon retains coolness after removing from fridge on a hot day due to the high specific cheat of water.

Question 19.
If you are chilly outside the shower stall, why do you feel warm after the bath if you stay in bathroom? (AS7)
Answer:

• In the bathroom, the number of vapour molecules per unit volume is greater than the number of vapour molecules per unit volume outside the room.
• When we try to dry ourselves with a towel, the vapour molecules surrounding you condense on your skin.
• Condensation is a warming process.
• Because of the condensation, you feel warm outside the shower stall when it is chilly.

Question 20.
Three objects A at 30°C, B at 303K and C at 420 K are in thermal contact. Then answer the follwing questions.
(i) Which are in “Thermal equibrium” among A, B and C?
(ii) From which object to another heat transferred? (2 Marks)
Answer:
i) 303K – 273K + 30K = 0°C + 30°C = 30°C.
∴ A and B objects are in ‘Thermal equibrium”.
ii) From object ‘C’ to objects ‘A’ and ‘B’ heat transferred.

Fill in the Blanks

1. The SI unit of specific heat is …………………. .
2. …………………. flows from a body at higher temperature to a body at lower temperature.
3. …………………. is a cooling process.
4. An object A at 10° C and another object B at 10 K are kept in contact, then heat will flow from …………………. to …………………. .
5. The latent heat of fusion of ice is …………………. .
6. Temperature of a body is directly proportional to …………………. .
7. According to the principle of method of mixtures, the net heat lost by the hot bodies is equal to …………………. by the cold bodies.
8. The sultryness in summer days is due to
9. …………………. is used as a coolant.
10. Ice floats on water because …………………. .
Answer:

1. J/kg – K
2. Heat
3. Evaporation
4. A, B
5. 80 cal/gm
6. Average kinetic energy of the molecules of the body.
7. net heat gained
8. high humidity
9. Water
10. the density of ice is less than that of water

Multiple Choice Questions

1. Which of the following is a warming process?
A) evaporation
B) condensation
C) boiling
D) all the above
Answer:
B) condensation

2. Melting is a process in which solid phase changes to ………………. .
A) liquid phase
B) liquid phase at constant temperature
C) gaseous phase
D) any phase
Answer:
B) liquid phase at constant temperature

3. Three bodies A, B and C are in thermal equilibrium. The temperature of B is 45° C. Then the temperature of C is ……………… .
A) 45° C
B) 50° C
C) 40° C
D) any temperature
Answer:
A) 45° C

4. The temperature of a steel rod is 330 K. Its temperature in ° C is ……………… .
A) 55° C
B) 57° C
C) 59° C
D) 53° C
Answer:
B) 57° C

5. Specific heat S =

Answer: C

6. Boiling point of water at normal atmospheric pressure is ……………… .
A) 0° C
B) 100° C
C) 110° C
D) -5° C
Answer:
B) 100° C

7. When ice melts, its temperature ……………… .
A) remains constant
B) increases
C) decreases
D) cannot say
Answer:
A) remains constant

10th Class Physics 1st Lesson Heat InText Questions and Answers

10th Class Physics Textbook Page No. 1

Question 1.
Take a piece of wood and a piece of metal and keep them in a fridge or ice box. After 15 minutes, take them out and ask your friend to touch them. Which is colder? Why?
Answer:
1) The metal piece is colder than the wooden piece.
2) Because more heat energy flows out of our body so metal piece gives coldness to our body, than wooden piece.

Question 2.
What could be the reason for difference in coldness of metal and wood?
Answer:

• Due to more heat energy loss by our body when touches the metal piece compared to the wooden piece.
• In other way we say degree of coldness of the metal piece is greater than that of. the wooden piece.

Question 3.
Does it have any relation to the transfer of heat energy from our body to the object?
Answer:

• Yes, the principle of calorimetry, means heat loss by hot body is equal to heat gained by cold body.
• This means that when heat energy flows out of our body we feel the coldness and when heat energy enters our body we feel hotness.

10th Class Physics Textbook Page No. 2

Question 4.
Why does transfer of heat energy take place between objects?
Answer:

• Due to the temperature difference between the two bodies which are in thermal contact.
• Now heat energy transfers from hot body to cold body until they attain same temperature.

Question 5.
Does transfer of heat take place in all situations?
Answer:
No, when the bodies are in thermal equilibrium there is no transfer of heat energy.

Question 6.
What are the conditions for transfer of heat energy?
Answer:

• Two bodies should have difference in temperature.
• They (two bodies) are in thermal contact with each other.
• When the bodies have equal temperature there is no transfer of heat energy.

Question 7.
What is temperature?
(OR)
Define temperature.
Answer:
Temperature : The measure of hotness or coldness of a body is called temperature.

Question 8.
How can you differentiate temperature from heat?
Answer:

• Heat is a thermal energy that flows from hot body to cold body. Temperature is measure of the hotness or coldness of a body.
• Temperature decides direction of heat (energy) flow, whereas heat is energy itself that flows.

10th Class Physics Textbook Page No. 2 & 3

Question 9.
Place a laboratory thermometer in a glass tumbler containing hot water. Observe the change in mercury level. Wffet change did you notice in mercury level? Did mercury level increase or decrease?
Answer:
The mercury level rises up that means temperature of the mercury level increases.

10th Class Physics Textbook Page No. 3

Question 10.
Place a laboratory thermometer in a glass tumbler containing cold water. Observe the change in mercury level. Did mercury level decrease or increase?
Answer:
The mercury level falls down that shows temperature of the mercury level decreases.

Question 11.
If two different systems A and B in thermal contact, are in thermal equilibrium individually with another system C (thermal contact with A and B), will the systems A and B be in thermal equilibrium with each other?
Answer:
Yes, A and B will be in thermal equilibrium with each other that means A and B will have equal temperatures.

Question 12.
How would you convert degree Celsius to Kelvin?
Answer:
Temperature in Kelvin = 273 + Temperature in degree Celsius. [K = t°C + 273]

10th Class Physics Textbook Page No. 4

Question 13.
Take two bowls one with hot water and second with cold water. Gently sprinkle food colour on the surface of the water in both bowls. How do food grains move? Why do they move randomly?
Answer:
We will notice that the grains of food colour move randomly (jiggle). This happens because of the molecules of water on both bowls are in random motion.

Question 14.
Why do the grains in hot water move more rapidly than the grains in cold water?
Answer:

• Temperature kinetic energy. So molecules in hot water have more KE than molecules in cold water.
• As water molecules in hot water move rapidly, grains in hot water move more rapidly than the grains in cold water.

10th Class Physics Textbook Page No. 4 & 5

Question 15.
a) Take a cylindrical jar and pour hot water and then coconut oil in the vessel (do not mix them). Keep thermometers in hot water and coconut oil as shown in figure. The reading of thermometer in hot water decreases, at the same time reading of the thermometer, kept in oil increases. Why does this happen?
Answer:

• Heat transfers from hot water to oil.
• So, water loses heat and shows downfall in temperature.
• Oil takes the heat and shows increasing in the temperature.

b) Can you say that water loses energy’?
Answer:

• Yes. Due to the temperature difference between the water and oil, water loses energy and oil gains energy.
• Thus some heat energy flows from water to oil.
• This means, the kinetic energy of the molecules of water decreases while the kinetic energy of molecules of oil increases.

c) Can you differentiate between heat and temperature based on the heat transmit activity?
Answer:
Heat is the energy that flows from a hotter body to a colder body. Temperature denotes which body is hotter and which is colder. So, temperature determines direction of heat (energy) flow, whereas heat is the energy that flows.

10th Class Physics Textbook Page No. 5 & 6

Question 16.
Place two test tubes containing 50 gm of water, 50 gm of oil in boiling water for same time.
a) In which material does the temperature rise quickly? Are the amounts of heat given to the water and oil same? How can you assume this?
Answer:

• Rise in temperature of oil is faster than the water.
• Yes, same amount of heat energy given to both the oil and water through boiling water.

b) Why does this happen in specific heat?
Answer:
This happens because rise in temperature depends on the nature of substance.

10th Class Physics Textbook Page No. 7

Question 17.
How much heat energy is required to rise the temperature of unit mass of substance (material) by 1°C?
Answer:
Energy equal to its specific heat.

Question 18.
Why is the specific heat different for different substances?
(OR)
Explain why specific heat values are different for different materials.
Answer:

• We know that the temperature of the body is directly proportional to the average kinetic energy of particle of the body.
• The molecules of the system have different forms of energies such as linear, rotational kinetic energy, vibrational energy and potential energy.
• When we supply heat energy, it will be shared in different forms and increase the energy in the system.
• This sharing will vary from material to material.
• If the maximum share of heat energy is spent to rise linear kinetic energy, then the system gets increasing in temperature.
• Due to differences in sharing different materials have different specific heats.

10th Class Physics Textbook Page No. 8

Question 19.
Take 200 ml of water in two beakers and heat them to same temperature and pour the water of two beakers into a larger beaker.
What do you observe? What could be the reason for the fact you observed?
Answer:

• The temperature of mixture remains the same.
• The reason is that the masses rise in temperature and the materials are same.

Question 20.
Heat the water in one beaker to 90°C and the other to 60°C. Mix the water from these beakers in large beaker. What will be the temperature of the mixture? What did you notice? Can you give reason for the change in temperature?
Answer:

• The temperature of mixture is 75°C.
• The reason is for a given material the temperature of mixture,
  
• Hot water gives heat to the cold water until thermal equilibrium takes place.
• So, the thermal equilibrium attains at 75°C.

Question 21.
ake 100 ml of water at 90°C and 200 ml of water at 60°C and mix the two. What is the temperature of the mixture? What difference do you notice in change of temperature?
Answer:

• The temperature of mixture is 70°C.
• The reason is here m₁ = 100 gm ; m₂ = 200 gm
  
• Final temperature of the mixture is less than the above case.
• If the quantity increases, the quantity of heat to transfer is also rises to attain thermal equilibrium.
  Here hotter body quantity is less and colder body quantity is high. So, the temperature at thermal equilibrium decreases and stands at 70° C.

10th Class Physics Textbook Page No. 10

Question 22.
When floor of room is washed with water, the water on the floor disappears within minutes. Why does water on the floor disappear after some time?
Answer:
Due to evaporation water disappears from the floor.

Question 23.
Pour a few drops of spirit on your palm. Why does your skin become colder? (1 Mark)
Answer:
Spirit absorbs heat energy from our palm and evaporates. So our palm becomes colder.

10th Class Physics Textbook Page No. 10 & 11

Question 24.
Take a few drops of spirit in two petri dishes separately. Keep one of the dishes under a ceiling fan and switch on the fan. Keep another dish with its lid closed. What do you notice? What could be the reason for this change?
Answer:
1) The spirit in the dish which is kept under the ceiling fan disappears.
2) Whereas we will find some spirit left in the dish that is kept in the lidded dish.
3) The molecules which are escaping from the surface is high and they can’t reach back to liquid due to wind blow. So, evaporation is high under fan.
4) At the same time evaporation is less in the dish which is closed by lid.

10th Class Physics Textbook Page No. 12

Question 25.
Does the reverse process of evaporation take place? When and how does it take place?
Answer:
1) Yes, the reverse process of evaporation takes place.
2) When the vapour molecules lose their kinetic energy which leads to lower the temperature, they convert into droplets.
3) This process is called condensation.

10th Class Physics Textbook Page No. 13

Question 26.
In early morning, during winter, you might have noticed that water droplets form on window panes, flowers, grass, etc. How are these water droplets formed?
(OR)
Why do water drops (dew) form on flowers and grass during morning hours of winter season?
Answer:

• During winter season, in the night times, atmospheric temperature goes down.
• The surfaces of window panes, flowers, grass, etc. become colder.
• The water vapour molecules touch the surfaces, gets cooled and lost its energy.
• Then water vapour condenses on the surface and water drops formed.
• The water droplets condensed on such surfaces are known as dew.

10th Class Physics Textbook Page No. 14

Question 27.
Are the process of evaporation and boiling the same? Explain.
Answer:

• No, they are different.
• Evaporation takes place at any temperature.
• But boiling occurs at particular temperature called the boiling point.

10th Class Physics Textbook Page No. 16

Question 28.
You might have observed coconut oil and ghee getting converted from liquid state to solid state during winter season. What could be the reason for this change? What happens to water kept in a refrigerator? How does it get converted from liquid phase to solid phase?
Answer:
1) If temperature of a substance decreases kinetic energy also decreases.
2) Kinetic energy decreases from water to ice. That means solid state to liquid state.
3) In winter season coconut oil in the form of liquid get down its temperature, hence its kinetic energy also decreases. So, it-freezes.
4) Water, which is kept in refrigerator loses the kinetic energy along with decreasing temperature and freezes.
5) In this way water converted liquid phase to solid phase.

Question 29.
Are the volumes of water and ice formed with same amount of water equal? Why?
Answer:
1) No, the volume of ice is greater than volume of water.
2) Water expands on freezing.
3) That means density of ice is less than density of water.

10th Class Physics 1st Lesson Heat Activities

Activity – 1

1. Explain the term temperature with example.
(OR)
What is the name given to degree of hotness or coldness? Explain the quantity with an example.
Answer:
Procedure: Take a piece of wood and a piece of metal and keep them in fridge or ice box.
Observation : When we touch both of them we feel that metal piece is colder than the wooden piece.

Explanation :

• This is due to more energy flow out of our body when we touch the metal piece as compared with wooden piece.
• The degree of coldness of metal is greater than that of the wooden piece.
• The degree of hotness or coldness is called temperature.
• From this example, we say metal piece is at a lower temperature compared to wooden piece.

Activity – 2

2. What is the measure of thermal equilibrium? How do you prove?
(OR)
How do you prove temperature is the measure of thermal equilibrium?
(OR)
Explain thermal equilibrium with an activity.
Answer:
Procedure :
Take two glass tumblers and fill one of them with hot water and another with cold water.
Explanation & Observation :
1) When we place a thermometer inside the hot water the mercury level of thermometer rises from initial position due to heat transferred from hotter body (hot water) to colder body (mercury in thermometer).
2) When we place the thermometer inside the cold water the mercury level comes down from its initial position due to transfer of heat from mercury (hotter body) to water (colder body).

Conclusion :

• Heat is a form of energy that flows from a body at higher temperature to a body at lower temperature until the temperature remains same for two bodies that is called thermal equilibrium.
• In the above case, the steadiness of mercury column shows that thermal equilibrium is achieved. That reading of mercury column gives temperature.
• Thus temperature is a measure of thermal equilibrium.

Activity – 3

3. Establish the relationship between temperature and average kinetic energy.
(OR)
Suggest an activity to prove that the average kinetic energy of the molecules is directly proportional to the absolute temperature of the substances.
(OR)
How do you prove that temperature of a body is an indicator of average kinetic energy?
Answer:
Procedure :

• Take two bowls one with hot water and second with cold water.
• Gently sprinkle food colour on the surface of the water in both bowls.

Observation :
We will observe the jiggling of grains of food colour in hot water is more when compared to jiggling in cold water.

Explanation :

• We know kinetic energy depends on speed motion of particles.
• So the kinetic energy of hotter body is greater than that of colder body.
• Thus the temperature of a body is an indicator of average kinetic energy of molecules of that body.

Conclusion :
Therefore average kinetic energy of molecules is directly proportional to absolute temperature.

Activity – 4

4. Write an activity which tells how heat transmits.
(OR)
In which direction does heat tend to flow? Prove it with an activity.
Answer:

Procedure :

• Take water in a container and heat it to 60° C.
• Take a cylindrical transparent glass jar and fill half of it with the hot water.
• Pour coconut oil over the surface of water.
• Put a lid with two holes on the top of the glass jar.
• Insert two thermometers through the lid in such a way that one inside coconut oil and other in water.

Observation & Explanation :

• Now we can observe that the reading of thermometer kept in water decreases while the reading of thermometer kept in oil increases.
• So temperature of water decreases whereas temperature of oil increases.

Conclusion :

• Heat transmits from hotter body to colder body.
• So temperature determines direction of heat flow.

Activity – 5 Specific Heat

5. Write an activity which gives the relation between rise in temperature and nature of material.
(OR)
“The rate of rise in temperature depends on the nature of substance.” Prove it with an activity.
(OR)
Draw a diagram and label the parts to prove that the rate of increase in temperature depends on the nature of substance.
(OR)
We can observe severe burns with hot oil when compared with hot water.
Which factor will decide this aspect? Explain this process with an example.
Answer:
Procedure :

• Take a large jar with water and heat it up to 80°C.
• Take two identical boiling test tubes with single-holed corks.
• Fill them, one of the boiling tubes with 50 gm of water and other with 50 gm of oil.
• Insert two thermometers in each of tubes and clamp them to retort stand and place them in a jar of hot water.

Observation :

• Observe the readings of thermometers every three minutes.
• We can observe that the rise in temperature of oil is higher than that of water.

Explanation :

• Since both the boiling tubes kept in hot water for the same interval of time, the heat supplied to oil and water is same but rise in temperature of oil is more.
• So we conclude that rise in temperature depends on the nature of substance (specific heat).

Activity – 6

6. Derive Q = mSAT.
(OR)
Establish relationship between heat energy, mass of the substance and rise in temperature.
(OR)
Derive an expression for heat energy.
(OR)
Derive an expression for factors affecting amount of heat energy absorbed.
Answer:
Procedure :

• Take two beakers of equal volume and take 250 grams of water in one beaker and 1 kg of water in another beaker.
• Note their initial temperatures.
• Now heat the two beakers up to 60° C.
• Note down the heating times.

Observation:

• We observe that-the water in large beaker takes more time.
• That means we need to supply more heat enepgy to water in larger beaker (greater quantity of water).

Conclusion :
From this we conclude that for some change in temperature the amount of heat (Q) absorbed by a substance is directly proportional to its mass (m).
Q ∝ m (when ∆T is constant) ………….. (1)

Procedure :
Now take 1 litre of water in a beaker and heat it and note the temperature changes (∆T) for every two minutes and observe the rise internals.

Conclusion:
We will notice that for the same mass (m) of water the change in temperature is proportional to amount of heat (Q) absorbed by it.
Q ∝ ∆T (when m is constant) ………….. (2)
From (1) and (2) Q m∆T (or) Q = mS∆T,
where ‘S’ is called specific heat of substance.

Activity – 7

7. a) How are you able to find the final temperature of the mixture of sample?
(OR)
What is the “Principle of method of mixtures”? Verify it with an activity.
Answer:
Situation – 1 :

• Take two beakers of the same size and pour 200 ml of water in each of them.
• Now heat the water in both beakers to same temperature.
• Now pour water from these beakers into a larger beaker and measure the temperature of the mixture.

Observation :
We can observe that there is no change in temperature.

Situation – 2 :

• Now heat the water in first beaker to 90° C and the other to 60° C.
• Mix the water from these beakers in a large beaker.

Observation :
We can find that the temperature of mixture is 75° C.

Situation – 3 :
Now take 100 ml of water at 90° C and 200 ml of water at 60° C and mix the two. Observation :
We can find that the temperature of mixture is 75° C.

7. b) Derive, a formula for final temperature of mixture of samples.
(OR)
Maveen added hotter water of mass m₁ kept at temperature T₁ to cold water of mass m₂ kept at temperature T₂. Find the expression to find temperature of mixture of samples.
Answer:
Procedure:
1) Let the initial temperatures of the hotter and colder samples of masses m₁ and m₂ be T₁ and T₂.
2) Let T be the final temperature of mixture.

Observation :
The temperature of the mixture is lower than hotter sample and higher than colder sample. Explanation :
So hot sample has lost heat, and the cold sample has gained heat.
The heat lost by the hot sample Q₁ = m₁S (T₁ – T)
The heat gained by the cold sample Q₂ = m₂S (T – T₂)
We know that heat lost = heat gained
Q₁ = Q₂
m₁ S(T₁ – T) = m₂ S(T – T₂)
\(\mathrm{T}=\frac{\mathrm{m}_{1} \mathrm{~T}_{1}+\mathrm{m}_{2} \mathrm{~T}_{2}}{\mathrm{~m}_{1}+\mathrm{m}_{2}}\)

Activity -8

8. Explain the process of evaporation phenomenon with an example.
(OR)
Srinu observed that spirit taken in a petri dish disappears after some time. Explain the process involved in it with an example.
Answer:
Procedure :

• Take a few drops of spirit in two petri dishes separately.
• Keep one of the dishes under a ceiling fan and keep another dish with its lid closed.
• Observe the quantity of spirit in both dishes after 5 minutes.

Observation :
We will notice that spirit in the dish kept under the ceiling fan disappears whereas we will find some spirit left in the dish that is kept in the lidded dish.

Explanation :

• The reason is that the molecules of spirit in dish continuously move with random speeds and collide with other molecules.
• During the collision they transfer energy to other molecules.
• Due to this collision the molecules at the surface acquire energy and fly off from the surface.
• Some molecules come back to liquid.
• If the number of escaping molecules is greater than returned number, then the number of molecules in the liquid decreases.

Conclusion :
When a liquid is exposed to air, the molecules at the surface keep on escaping from the surface till the entire liquid disappears into air. This process is called evaporation.

Activity – 9

9. Explain the process of condensation with example.
(OR)
Explain the process of condensation with an activity.
(OR)
Karan told his friend that he observed that there are some water droplets outside a cold soft drink bottle. Explain the phenomenon involved in the formation of these droplets.
Answer:
Procedure :
Place a glass tumbler on the table. Pour cold water up to half of its height.

Observation :
There are droplets formed outside of the glass.

Explanation :

• The reason is that the surrounding air contains water molecules in the form of water vapour. When the water molecules strike the surface of the glass tumbler which is cool, they lose their kinetic energy.
• This energy lowers the temperature of vapour and it turns into droplets.
• The energy lost by water molecules in air is gained by the molecules of the glass tumbler.
• Hence the average kinetic energy of glass molecules increases. In turn the energy is transferred to water molecules in die glass.

Conclusion :

• So the average kinetic energy and temperature of water in glass increases. This is called condensation.
• Condensation is the phase change from gas to liquid.

Activity – 10

10. Explain the process of boiling with an example.
(OR)
Why do we observe bubbles on the surface of water which has been heated ? What is the phenomenon involved in it? Explain.
Answer:
Procedure :
Take a beaker of water, keep it on the burner and note the readings of thermometer for every two minutes.

Observation :

• We will notice that the temperature of the water rises continuously till it reaches 100° C.
• Once it reaches 100° C the temperature remains same and a lot of bubbling on the surface takes place. This is called boiling of water.

Explanation :

• It happens due to when water is heated the solubility of gases it contains reduces.
• As a result, bubbles of gas are formed in the liquid.
• Evaporation of water molecules from the surrounding liquid occurs into these bubbles and they become filled with saturated vapour.
• At a certain temperature, the pressure of the saturated vapour inside the bubbles becomes equal to the pressure exerted on the bubbles from the outside.

Conclusion :

• As a result, these bubbles rise rapidly to the surface and collapse at the surface releasing vapour present in bubbles into air at the surface. This process is called “boiling”.
• This temperature is called ‘boiling temperature”.

Activity – 11

11. Explain the process of melting and latent heat of fusion.
(OR)
When ice is heated to 0°C it starts to turn into water. But temperature remains ‘ constant for some time. What is the process involved in this? Explain.
Answer:
Procedure :

• Take small ice cubes in a beaker. Insert the thermometer in the beaker.
• Now start heating the beaker and note down readings of thermometer every one minute till the ice completely melts and gets converted into water.
• Before heating the temperature of ice is 0°C or less than 0°C.

Observation :

• We will observe that the temperature of ice at the beginning is equal to or below 0°C.
• If the temperature of ice is below 0°C, it goes on changing till it reaches 0°C.
• When ice starts melting, we will observe no change in temperature though you are supplying heat continuously.

Explanation:

• Given heat energy uses to break the bonds (H₂O) in ice and melts.
• So, temperature is constant while melting.

Conclusion:

• This process is called melting. In this process, heat converts solid phase to liquid phase.
• The temperature of the substance does not change until all the ice melts and converts into water.
• The heat given to melting is called latent heat of fusion.
• The heat required to convert 1 gm of solid completely into liquid at constant temperature is called “latent heat of fusion”.

Activity – 12

12. Why does a glass bottle tilled with water break when it is placed in deep freezer for some time?
(OR)
Prove that density of ice is less than that of water.
(OR)
How do you prove that volume of ice is more than that of water?
Answer:
Procedure :

• Take a small glass bottle with a tight lid and fill it with water, without any gap and fix the lid tightly.
• Put the bottle into the deep freezer of a refrigerator for a few hours.

Observation :
When we take it out from the deep freezer, we can observe that the glass bottle breaks.

Explanation :

• These cracks on the bottle due to expansion of the substance in the bottle.
• This means water expands on freezing.

Conclusion :

• Water expands on freezing.
• Ice has less density than water.

AP State Board Syllabus AP SSC 10th Class Biology Solutions Chapter 5 Coordination – The Linking System Textbook Questions and Answers.

AP State Syllabus SSC 10th Class Biology Solutions 5th Lesson Coordination – The Linking System

10th Class Biology 5th Lesson Coordination – The Linking System Textbook Questions and Answers

Improve your learning

Question 1.
Fill In the missing sections In the following flow-chart.

Answer:

Question 2.
Do you think body’s team work maintains functioning of our body? Justify your answer with an example.
Answer:

1. Yes. Body’s team work maintains functioning of our body.
2. All our functions are carried out by an effort of several systems working together.
3. The human body has a set of systems which regulate the internal environment and strive to give our cells the necessary condition as they need to function.
4. We cannot use only the skeletal system or muscular system.
5. To do any function several other systems also have their own roles to play.
6. The pathway involving the way that our organs tissues and cells pickup signals from their surroundings and respond to them that triggers different functions in our body as well as by our body.
7. When all the organs and organ systems work as a unit then the organism will survive.
8. For example our eyes, ears, legs should coordinate with each other when crossing the road. Otherwise we may met with an accident.

Question 3.
Give an example of coordination in your body where both hormonal and nervous controls function together.
Answer:

1. Several functions in our body are controlled by nerves, while many others are controlled by hormones.
2. When we are afraid, the rate of heart beat increases, the breath rate will be faster, blood pressure increases, the hair on the body becomes errect and we get goose bumps.
3. We might not observe our pupil dilation, skin becomes more sensitive. We come to normally only after we reach a safe spot.
4. The various actions of the body are controlled by hormones and coordinated by nervous system.
5. In these type of conditions nervous system and endocrine system work together to bring about control and coordination.
6. Another example for nervous and hormonal coordination. When the mother feeds the baby, the baby sucks the nipple for milk. This information is send to the brain by sensory nerve. Brain orders the pituitary gland to release the hormone oxytocin. Oxytocin helps in the ejection of milk from the mammary glands.

Question 4.
Consider that you are passing by a garbage disposal area and you immediately
cover your nose. Arrange the events below in a logical order by marking them from 1 to 5 to trace the events that happen in the nervous system from detection of foul smell (stimulus generation) to covering your nose (response).
i) At the end of the axon, electrical impulse releases chemicals.
ii) Stimulus received by the dendrites of a neuron sets off chemical reaction that creates an electrical impulse.
iii) Electrical impulse transmitted through cell body and axon.
iv) The chemicals cross the synapse and reach the next neuron. Similarly, the electrical impulse crosses several neurons.
v) Finally, the impulse is delivered from neuron to the gland that helps in recognition of the foul smell and muscle cells that help in covering the nose.
Answer:
The following events occur in nervous system for detecting foul smell of garbage, ii, iii, i, iv, v

Question 5.
What is a Synapse? How is it useful in transfer information?
Answer:

1. Definition: Synapse is a functional region between two neurons where information from one neuron is transmitted or relayed to another neuron.
2. Through synaptic region is with minute gaps it does not have any protoplasmic connection between them.
3. Information is passed from one nerve cell to the other through these gaps either in the form of chemical or electrical signals or both.

Question 6.
Distinguish between
a) Stimulus and Response
b) Afferent and Efferent nerves
c) Central nervous system and peripheral nervous system
d) Receptor and effector
Answer:
a) Stimulus and Response

b) Afferent and Efferent nerves

c) Central nervous system and peripheral nervous system :

d) Receptor and effector:

Question 7.
How does phototropism occur in plants?
Answer:

1. Bending of plants towards light is called phototropism. (Photo = light) (tropism = movement)
2. For example a creeper which is growing near the window bend towards sunlight.
3. Auxins are the phyto hormones which are present at the tip of the shoot respond the plant to bend towards sunlight.

Question 8.
Give an example and explain how plants may immediately respond to a stimulus.
Answer:

1. The plant responding to stimulus is mimosa pudica is the example.
2. Mimosa pudica leaves have pad like sweelings at the base are called PULVINI.
3. Here cells contain water and large intercellular spaces. Due to water pressure pulvini hold the leaf errect.
4. When we touch the leaves, an electrical impulse is generated due to plant hormone.
5. Because of this hormone water in the pulvini cells which are closer to the leaf vein migrate to other side’of the cells.
6. Then pulvini loss its fitness hence leaves become fold. After 20 to 30 minutes water comes back leaves become errect.

Question 9.
Suggest an experiment to show how roots grow away from light in most plants.
Answer:
Aim: To prove that roots grow away from light in most plants.
Material required: Glass jar, Bean seed.
Procedure:

1. A plant jar is taken and filled with mud.
   
2. A bean seed is sown just adjacent in the inner wall of the jar.
3. So that it is easy to observe the growth of root and shoot.
4. After 4-5 days the germination of the seed is observed.
5. Keep the jar in the sunlight. We observe the growth of roots and shoot.
6. Finally the jar is tilted to keep the growing plant horizontally.
7. After the growth of 4-5 days, tilt the glass jar and keep the plant horizontally.

Observation: It is observed that the roots extends downwards to the earth that is away from the sun light and the shoot grows towards sunlight.
Conclusion: By the above experiment it is proved that roots grow towards gravity (earth) away from sun light.

Question 10.
Give an example to show how hormones can influence visible changes in your body.
(OR)
What are the effects of hormones on human beings?
Answer:

1. Endocrine glands secrete chemical substances called Hormones directly into blood.
2. Hormones act on the cells of other organs and increase or decrease the metabolism of carbohydrates, proteins and fats.
3. The external features by which the males and females can be distinguished are called secondary sexual characters.
4. Testosterone in males and estrogen in females promotes the development of secondary sexual characteristics.
5. For example, if a dog chases us, our nervous system stimulate the adrenal glands to secrete more adrenaline hormone into our body.
6. When we are afraid, the rate of heart beat increases, the breath rate will be faster, blood pressure increases, the hair on the body becomes errect.
7. All these changes occur due to the production of Adrenaline hormone.

Question 11.
How does a neuron differ from an ordinary cell in structure? Write notes.
Answer:

Question 12.
Is the structure of neuron suitable for transmission of impulses? Analyse.
Answer:

1. Yes. The structure of neuron is suitable for transmission of impulses.
2. Neurons are the functional units which receive and process information and generate responses.
3. Cell body is the centre for all the synthetic activity of the neuron.
4. Dendrites arise from the cell body receive information from other neurons and carry this information to the cell body.
5. The axon or nerve fibre gives out several branches that end in nerve terminals. These make connect with the dendrites or the axons of another neuron.
6. Myelinated sheath prevents the leakage of electrical currents from axon. Myelinated axons conduct impulses much faster than unmyelinated axons.

Question 13.
Man is the most intelligent animal. What could be the fact that helped us to reach such a conclusion?
Answer:

1. Man is the most intelligent animal in animal kingdom.
2. This is possible by well development of brain and its marvellous function.
3. Human brain has abilities to learn from concepts.
4. It understands, applies logic and reason.
5. The brain also recognizes patterns and comprehends ideas.
6. The human brain has ability in making plans, solving problems, making decisions and retaining information.
7. Man is the only animal who uses language to communicate.
8. Intelligence enables humans to experience and think.
9. It has also consciousness and self-awareness.

Question 14.
The axon of nerve cell in hand is shorter than the axon of nerve cell in leg. Do you support this statement? Why?
Answer:

1. Yes, I support the above statement.
2. The axon of nerve cell in hand is shorter than the axon of nerve cell in leg.
3. The sciatic nerve is the large nerve in humans and animals. It begins in the lower back and runs through the buttock and lower limbs.
4. Sciatic nerve present in the leg is the largest and widest single nerve in the human body. It measures about 1 mt in length.
5. Usually the length of leg is more in size than hand. Hence the axon of nerve cell in hand is shorter than the axon of nerve cell in leg.

Question 15.
Organs respond to the external stimulus by a fraction of second. How do you feel about such controlling mechanism of human body?
Answer:

1. Organs responding for the external stimuli by a fraction of second are due to reflex action.
2. Reflex actions are very important as they save us from painful or dangerous stimuli.
3. Reflex actions or reflexus are fast, immediate automatic and involuntary responses of the body.
4. They help in the body as they save us from painful or dangerous stimuli.
5. Reflexes occur without our thinking.
6. Brain is not involved in the execution of several reflexes.
   Ex: Withdrawing our hand when we touch hot subject.

Question 16.
State whether the following actions are voluntary action, reflex action or conditioned reflex.

1. Blinking
2. Cleaning the table
3. Playing on the key board
4. Salivating when food is put in the mouth
5. We close our ears when we hear unbearable sound

Answer:

1. Blinking: Involuntary action or reflex action.
2. Cleaning the table: Voluntary action.
3. Playing on the keyboard: Conditioned reflex.
4. Salivating when food is put in the mouth: Involuntary or Reflex action.
5. We close our ears when we hear unbearable sound: Involuntary or reflex action.

Question 17.
What will happen to the potted plant kept near window in the room?
(OR)
Draw a diagram of a plant showing phototropism. Explain why plants possess such type of response.
(OR)
A plant which grows near a window bends towards sun light. Write the reason for it.
Answer:

1. The potted plant which is kept near the window in the room, grows towards light.
   
2. Auxins acts on bending of stem of show a response to the sun light.
3. More auxin collects on the light illuminated side of the stem. So cells on that side grow faster.
4. On opposite side cells grow slow to make the stem bend.
5. Auxins are the plant hormones responsible for the growing of the stem towards light.
6. Auxins are synthesized at the tip of the stem (meristematic tissue).
7. Bending of the plant towards light is called phototropism.

Question 18.
What happens if all the functions of the human body are controlled only by brain?
Brain controls all the functions of the human body. Comment on it.
Answer:

1. If all actions of the human body are controlled by brain, our body will get harm in dangerous situations.
2. Some actions may be delayed and our brain could not conduct reflex actions, which require immediate action to a stimulus.
3. For example, when we touch a hot object, we require an immediate response to save our hand. If the brain controls this action, the time taken will be more and our hand will burn.
4. So, it is controlled by spinal cord, the response will be quick, and we may escape the danger.
5. Nerves can not reach the every corner of the body, whereas hormones of endocrine glands can do that.
6. So it’s not good that all functions are controlled by brain.

Question 19.
If you visit a doctor, what doubts you would like to clarify about pancreas?
Answer:

1. What is pancreas?
2. Where is pancreas located in our body?
3. Why is it called mixed gland?
4. What is the exocrine part of pancreas?
5. What is the endocrine part of pancreas?
6. What are the cells that secrete hormone insulin?
7. What is the function of insulin?
8. What happens if required amounts of insulin is not produced?
9. What are the symptoms of diabetes?
10. How can diabetes be controlled?

Question 20.
Take a small potted plant. Cover base portion of the plant tightly and hang the part upside down. Observe the plant for a week. Based on your observation how can you support phototropism?
Answer:
Aim: To prove that phototropism is a character that is carried by stem.

Apparatus: Potted plant, a strong small rope.
Procedure : Take a small potted plant. Cover the base portion of the plant tightly so that the plant along with soil do not fell down. Now take a rope and hang the potted plant upside down to a support firmly.
Observe the plant after a week.
Observation: We observe that the end of the stem which is upside down takes ‘U’ turn and grows towards light.
Conclusion: Phototropism is a response of plants towards light. That the stem grows towards light that is negatively to gravitation. Auxins are responsible for phototropism.

Question 21.
Take a cock feather touch smoothly at different parts of your body. Findout which portion of the body has high sensation. Is this similar during sleeping ? Prepare a report on it.
Answer:
Aim: To prove that our body shows high sensation in different parts.
Apparatus : Cock feather.
Procedure: Take a cock feather. Touch smoothly at different parts of our body with the cock feather.
Observation : It is observed that some of the body parts like palms of hands and soles of feet there is less sensation than the other body parts because the skin is thick. Some other parts where the skin is thin, the sensation is more.
Report: The nerve endings are situated in the skin. These nerve endings are responsible for the sensation of the body.

Question 22.
What procedure you follow to understand the effect of plant growth hormones (in agar medium) in the terminal portion of the tip of stem (coleoptile)?
Answer:
Aim: To show the growth of Avena coleoptile involves a chemical substance.
Apparatus: Oat seedlings (Avena sativa), coleoptile, a slice of agar, a sharp blade. Procedure:

1. Take some oat seedlings.
2. Their coleoptile tips are cut off.
3. Place the tips on a slice of agar and leave them for about an hour.
4. Cut the agar into small blocks and place a block on one side each stump of the decapitated plants.
5. The plants were kept in the dark during the entire experiment.
6. Observe the plants after one hour.

Observation :

1. Within one hour a distinct bending away from the side on which the agar block was placed is observed.
2. Agar block that had not been contact with coleoptile doesn’t show any bending.
   

Conclusion : The coleoptile tip exerted its effect by means of a chemical stimulus such as an electrical impulse. This chemical stimuls came to be known as auxin.

Question 23.
Collect information on the actions controlled by spinal cord by using reference books from your school library.
Answer:
Spinal cord:

1. Spinal cord is a long and cylindrical structure. It passes through vertibral column extending all along the dorsal surface of trunk.
   
2. Vertebrae of the vertebral column protects the spinal cord.
3. The spinal cord has two major functions, a) carrying information b) coordinating reflexes.
4. It receives sensory information through the afferent nerves from the sensory receptors throughout the body and send them to the brain.
5. It also carries information from the brain through efferent fibres to the muscles and glands.
6. It coordinates reflexes without the involvement of the brain.

Thus the spinal cord has both communicative and integrative functions.

Reflex actions:

1. Excepting the sensory and motor functions spinal cord controls some other important function also. These are called as reflex actions.
2. The spinal cord does not take any assistance from the brain. Reflex actions are automatic, unlearned, involuntary and in born responses.
3. Therefore these actions are suddenly in nature and have a purpose of protecting the individuals or his / her organs from sudden danger.

Question 24.
Read the following sentences and compare with endocrine glands.

Pheromones are chemical substances secreted by organisms. These act as chemical signals secreted by exocrine glands. Pheromones are used as signals by the members of same species. Honey bee secretes pheromones that attract other bees to the location of food.
Answer:

Question 25.
Collect the information about cranial nerves, spinal nerves from internet or from your school library.
Answer:
Spinal cord :

1. Spinal cord is a long and cylindrical structure passing through the vertebral column.
2. The vertebrae (back bones) of the vertebral column protect the spinal cord from injuries.
3. From the sides of spinal cord, 31 pairs of nerves take their origin one from each side and supply branches to various parts of the body.
4. Basic function of spinal cord is to act as a relay station – receiving information from various parts of the body parts below the head and send this information to the brain.
5. Similarly, it receives information from brain and sends this information to other parts of the body.
6. In addition to this, spinal cord also plays a major role in the RFELEX ACTIONS.
7. The message received from the sensory nerve is passed into spinal cord. It is analyzed by the INTER NEURON present in the spinal cord and response is given. It is conveyed to the effector organ through motor nerve. The effector organ shows the response.
8. Thus spinal cord saves us from dangerous stimuli through it’s REFLEX ACTIONS.

Question 26.
Draw a picture representing connection between dendrite – dendrite, axon – dendrite. Why do they connect like that?
Answer:

1. The nerve cell is the structural and functional unit of nervous system.
   
2. It consists of more than 100 billion of them, which communicate with each other in a specific manner.
3. Dendrites of one nerve cell connects to the other or to the axons of another nerve cell through connect points called as a synapse.

Question 27.
Draw a neatly labelled diagram of Brain and write few points how it is protected.
Answer:
Protection of Brain :

1. Brain is present in the hard bony box called CRANIUM.
   
2. It is covered by three layers called MENINGES.
3. The space between the inner layer is filled with fluid called cerebrospinal fluid,
4. It serves a shock-absorbing medium and protects brain against shocks/ jerks along with the meninges and cranium.

Question 28.
You are walking in the traffic suddenly you heard a loud sound. How does coordination take place in this situation among respected organs? Draw a block diagram to explain this situation.
Answer:

Question 29.
Make a model of neuron using suitable materials.
Answer:
Required materials: A chart, twine thread, fevicol, sticker.

Question 30.
Observe different actions performed by your classmate for a period of 45 minutes. Out of these actions which are controlled by voluntary and involuntary pathways?
Answer:
Voluntary actions:

1. Standing
2. sitting
3. laughing
4. drinking
5. moving
6. clapping
7. carrying books
8. reading
9. writing
10. talking

Involuntary actions:

1. Blinking of eyes
2. swallowing
3. breathing
4. listening etc.

Question 31.
Its very interesting to watch a creeper entwining its tendril to the support. Is not it? How do you express your feelings in this situation?
(OR)
Plants also respond to external stimuli. How do you feel about this?
Answer:

1. A very interesting thing in plants is movement of tendrils.
   
2. All plants show positive response to phototropism.
3. But creepers like cucumber, bittergourd the stem is weak and thin. Hence plant cannot grow erect.
4. Tendrils play a vital role to make the plant erect. Tendrils are thin thread-like growth on the leaves or stems of climbing plants.
5. They grows towards support and wind around them.
6. This type of response to make contact or touch is called thigmotropism.
7. Nature only finds it’s way to grow and survive on the earth.

Question 32.
Hormones are released at a specific place, specific time for a specific function. Prepare a cartoon on the hormones with a nice caption.
Answer:

Fill in the blanks.

1. The largest region of the brain is ———–.
2. A point of contact between two neurons is ———–.
3. ———– phytohormone is responsible for cell elongation and differentiation of shoots and roots.
4. Thyroxine is responsible for ———–.
5. Gibberellins and auxins promote growth in plants while absciscic acid arrests the same. Some situations are discussed here. State which hormones would be needed and why?
   a) A gardener wants large dahlias, he should use along with nutrients and other things ———– hormone.
   b) In a dwarf plant the branches have to be thickened one would use the ———– hormone.
   c) Seeds are to be stored a long time ———– hormone can help.
   d) Cutting the apex or tip of plants so that there are several lateral buds ———– hormone can be used.
   e) The part of the brain that helps you in solving puzzles is ———–.

Answer:

1. cerebrum
2. synapse
3. Auxin
4. General growth rate and metabolic rate
5. a) Auxin b) Gibberellin c) Absciscic acid d) Cytokinins e) Cerebrum

Choose the correct answer.

1. A person has loss of control on emotions, which part of brain stops its function ? [ ]
   A) Cerebrum
   B) Diencephalon
   C) Mid brain
   D) Cerebellum
2. Leaf movement in mimosa helps to [ ]
   A) Reduce photosynthesis
   B) Protect from grazers
   C) Releasing phytohormones
   D) Regulate its growth
3. Diabetes is related to this gland. [ ]
   A) Thyroid
   B) Pancreas
   C) Adrenal
   D) Pituitary

10th Class Biology 5th Lesson Coordination – The Linking System InText Questions and Answers

10th Class Biology Textbook Page No. 95

Question 1.
What helps us to respond to such signals?
Answer:
There is a sequence of events that bring about responses. They start from detecting changes in environment.

Question 2.
Why does the living body respond to such signals?
Answer:
The ability to react to particular stimulus in a particular situation must be of great importance in ensuring the survival of the organism.

10th Class Biology Textbook Page No. 96

Question 3.
What did Galen conclude after his observations?
Answer:
After the observations of his patient, Galen a Greek physiologist concluded that nerves were of two types – those of sensation and those of action.

Question 4.
Why do you think Galen drew such a conclusion?
Answer:
According to Galen the blow in the neck of his patient had damaged the nerves of sensation but had not affected its action. Then Galen concluded that nerves were of two types.

10th Class Biology Textbook Page No. 98

Question 5.
Which organ of our body was the detector and which was the effector in Activity -1?
Answer:
In Activity -1, Eye was the detector and fingers were the effector.

Question 6.
What do you think that the information carried on the afferent and efferent nerves?
Answer:
The information carried by afferent nerve is “scale is falling”.
The information carried by the efferent nerve is “to hold the scale”.

10th Class Biology Textbook Page No. 99

Question 7.
What other effectors would act under these circumstances?
Answer:

1. Withdraw our hands, when our fingers touch a hot object.
2. Closing eyes when bright light is focussed on eyes.
3. We sneeze when something enters the nose.
4. We cough when inhaled dust or some other circumstances.

Question 8.
What does this tell us about the association nerves?
Answer:
The sensory nerves in the spinal cord makes connections with other neurons in the grey matter. These neurons are called association neurons or interneurons. The association neurons process the information and generate responses.

10th Class Biology Textbook Page No. 100

Question 9.
Think of any action and try to make a sketch of reflex arc.
Answer:

10th Class Biology Textbook Page No. 102

Question 10.
According to you what would be the function of the spinal cord?
Answer:
Functions of the spinal cord :

1. Spinal cord sends information received from different parts of the body to brain.
2. Also it sends the information to various parts received from brain.
3. Spinal cord also play a major role in reflex actions.

Question 11.
Are all functions of our body under direct control of the brain and spinal cord? Why do you think so?
Answer:
Yes. All the functions of our body are under direct control of the brain and spinal cord. The 43 pairs of peripheral nervous system associated with brain and spinal cord plays an important role in disposing our body functions.

10th Class Biology Textbook Page No. 103

Question 12.
Which root according to you gets signals from afferent nerves?
Answer:
The dorsal root of the spinal cord gets signals from afferent nerves.

Question 13.
What do you think the end of these nerves act at the muscular end?
Answer:
At the ends of these nerves can involuntarily control several functions of regions like internal organs, blood vessels, smooth and cardiac muscles and is called an autonomous nervous system. It has voluntary control of muscles of some areas of skin and the skeletal muscle.

10th Class Biology Textbook Page No. 104

Question 14.
To which organs of the body do the nerves go from the ganglions near the vertebral column?
Answer:
The organs like heart, lungs, stomach, intestines, urinary bladder, kidneys, hand fingers of the body, the nerves go from the ganglions near the vertebral column.

10th Class Biology Textbook Page No. 105

Question 15.
What are the organs that receives nerves starting from the brain?
Answer:
Eye, mouth, tongue, salivary glands are the organs receives nerves starting from the brain.

Question 16.
Which are the organs whose activities are influenced by the sympathetic nervous system?
Answer:
Eye – pupil, heart, lungs, blood vessels, sweat glands, digestive tract, kidneys, penis are the organs influenced by the sympathetic nervous system.

Question 17.
Which are the organs whose activities are influenced by the parasympathetic system?
Answer:
Stomach, intestines, salivary glands, reproductive organs, etc., are influenced by para sympathetic system.

Question 18.
What do you understand about the functions of parasympathetic nervous system?
Answer:
Parasympathetic nervous system slows down the body functions such as feed & breed, rest & digest, sexual arose, lacrimation, urination, defecation and digestion.

Question 19.
What do you understand about the functions of sympathetic nervous system?
Answer:
Sympathetic nervous system speeds up the body functions. Dilates pupil, heart – increases rate, force of contraction, lungs dilates, blood vessels contraction, etc. are the functions controlled by sympathetic nervous system.

10th Class Biology Textbook Page No. 107

Question 20.
Have you ever observed the duration of anger?
Answer:
The duration of anger will be sometimes ten minutes or fifteen minutes or according to the situation.

Question 21.
Why does anger come down?
Answer:
Anger is always short lived factor. Increased levels of adrenalin are responsible for anger. When the levels of adrenalin in the blood come down slowly. We came to normal state.

Question 22.
What may happen if anger persists for a longer period?
Answer:
If anger persists for longer time, regular metabolic activities are disturbed.

Question 23.
What will happen if it is continued for longer periods of time?
Answer:
The sugar levels in the blood rise than normal level. Blood pressure increases, burning sensation in the heart, stomach upsets are the some of the abnormal conditions may happen.

10th Class Biology 5th Lesson Coordination – The Linking System Activities

Activity – 1

Holding a falling stick.
Answer:
Take a long scale or stick at least around V2 meter. Keep your fingers in holding position. Ask your friend to hold the stick / scale near the end and let the other end be suspended between your fingers.
Let there be a very small gap around a centimeter between your thumb and stick/scale and fore finger. Now let you friend allow it to fall. Try to hold it.

1. Could you hold it exactly at the point where it was suspended between your fingers?
   Answer:
   No. I cannot hold it exactly at the point.
2. How far up was this point from the end suspended between your fingers?
   Answer:
   2 cm up (nearly at the end of the scale).
3. Why did this happen?
   Answer:
   Because it is the sudden action. To hold it fastly. The exact point went up.
4. How fast do you think the process was?
   Answer:
   The process was so fast in a fraction of a second.
5. What makes this kind of communication possible?
   Answer:
   Rapidity of response indicates an efficient communication system linking those parts that pick up stimuli that trigger a response by the nervous system.

Activity – 2

Observe the permanent slide of nerve cell or neuron under microscope and try to find out its parts. Compare with the following diagram.
Answer:
Structural unit of the nervous system is the nerve cell or neuron. Neuron is highly specialised cell. Neurons carry impulses or messages. New nerve cells are not produced to replace the damaged or destroyed nerve cell. A neuron has three parts. They are

1. cyton
2. axon and
3. dendrites

1. The cyton:

1. It is also called the cell body.
2. It has a large and round nucleus.
3. In the cytoplasm of the cyton, nissl granules are present.

2. Axon:

1. It is the long and cylindrical process that arises from the cyton.
2. In some nerve cells, axon is surrounded by a layer of fatty material known as myelin sheath.
3. The myelin sheath is not continuous throughout length of the axon.
4. It is broken at regular intervals.
5. These broken spots are called as nodes of Ranvier.

3. Dendrites: Arise from the cyton they are much branched, when compared to axon.

Activity – 3

What is knee jerk reflex?
Answer:
Cross the legs, in a seated position, so that the lower half of the uppermost leg hangs freely over the other. Strike the area below the knee cap sharply, while firmly grasping the front part of the thigh with the other hand. Note the changes in shape of the thigh muscles.

1. What changes do you observe in the thigh muscle?
   Answer:
   The thigh muscles get contracted and becomes short.
2. What do we call this type of response?
   Answer:
   This type of responses are called involuntary actions. Such type of actions in the body are carried by without our involvement and our knowledge.
3. What do we call the action of kicking a foot ball?
   Answer:
   Kicking of a foot ball is a voluntary action’ These actions are within our control.
4. How is the knee jerk action takes place?
   Answer:
   In the knee jerk action a nerve pathway was involved.
   v) Do you think most of the functions in our body go about in an involuntary manner? Why ? Why not ?
   Answer:
   Most of our body functions are done without the involvement of our knowledge. For example, heart beating, respiration, digestion, etc., are the involuntary actions which are carried by our body.

Activity – 4

Touch the leaves of Mimosa pudica (athipathi, touch me not) plant and observe the response of leaves.

1. Are they folding?
   Answer:
   When the leaves of Mimosa are touched the leaves get folding. Touching the leaves is the stimulus and folding is the response.
2. In which direction the folding of the leaves take place?
   Answer:
   The folding of the leaves take place inward direction.
3. Give some examples of situations in plants responding to a certain stimulus.
   Answer:
   Examples: The sun flower turning to the direction of sun, the bending response of the plant when it is kept in the dark. Some of leaves of the trees opens at the day time and closes after sun set.
   Phototropism of stem and geotropism of roots, hydrotropism of roots of plants growing towards water and thigmotropism where the creepers like cucumber, bitter – gourd takes the help of tendrils and wind around the support are some of the examples of response to stimulus in plants.

Activity – 5

Take a glass jar and fill with soil. Sow a bean seed near the wall of the jar. After 4 – 5 days you will notice seed germination. Keep the jar under the sun. Observe how root and shoot grows. Then tilt the glass jar and keep the plant horizontally. Observe the direction of the root and shoot growth for more than a week.

1. Does the shoot take a horizontal tilt after a week?
   Answer:
   After a week the shoot takes a horizontal tilt.
2. Which side of the shoot may have grown more and which side less to bring about this effect?
   Answer:
   The shoot grown more towards the light and less where light is not falling.
3. Do you find any difference in the shape of epidermal cells?
   Answer:
   The straight portions of the epidermal cells shows no bending but the bending portions of epidermal cells shows bending.
4. Who performed experiments on phototropism?
   Answer:
   Charles Darwin and his son Francis Darwin performed some experiments on phototropism.
5. What did they do in their experiment?
   Answer:
   Charles Darwin and his son Francis Darwin performed experiments on phototropism. They covered the terminal portion of the tip of stem (coleoptile) with a cylinder of metal foil. Exposed the plant to light coming from the side.
6. What did they observe by that experiment?
   Answer:
   They observed that the bending towards the light (characteristic) of the seedling did not occur. If light was permitted to penetrate the cylinder bending occurred normally.
7. What did Charles Darwin and his son Francis Darwin state on their experiment?
   Answer:
   They stated that when seedlings are freely exposed to a lateral light some ‘influence’ is transmitted from upper to the lower part causing the material to bend.
8. What are the experiments of F.W. Went and how did he succeeded in separating ‘influence’ from the plant?
   Answer:
   F.W. Went cut off coleoptile tips from oat seedlings. He placed the tips on a slice of agar and left them for about an hour.
   He then cut agar into small blocks and placed a block on one side each stump of the decapitated plants. They were kept in the dark during the entire experiment. Within one hour he observed a distinct bending away from the side on which agar block was placed.
9. How did Went come to know about auxin?
   Answer:
   Went interpreted these experiments as showing that the coleoptile tip exerted it’s effect by means of chemical stimulus rather than a physical stimulus such as an electrical impulse.
   This chemical stimulus came to be known as auxin. In this way the first plant hormone auxin was discovered by F.W. Went.
10. What is the meaning of auxin in Greek?
    Answer:
    The Greek word auxin means to increase.

AP State Board Syllabus AP SSC 10th Class Physics Solutions Chapter 7 Human Eye and Colourful World Textbook Questions and Answers.

AP State Syllabus SSC 10th Class Physics Solutions 7th Lesson Human Eye and Colourful World

10th Class Physics 7th Lesson Human Eye and Colourful World Textbook Questions and Answers

Review of Your Previous Knowledge

Question 1.
What is the function of lens in human eye?
Answer:
The eye lens forms a real image on retina then we can see the objects.

Question 2.
How does it help to see objects at long distances and short distances?
Answer:
Eye lens can adjust itself in shape, so that it helps to see the objects at long and short distances.

Question 3.
How is it possible to get the image at the same distance on the retina?
Answer:
When the eye is focussed at distant object, the ciliary muscles are relaxed. So the focal length of eye lens adjusted itself which is equal to the distance of object from the retina. Then we can see the object clearly.
When the eye is focussed on a closer object the ciliary muscles adjust the focal length in such a way that the image is formed on retina and we see the object clearly.

Question 4.
Are we able to see all objects in front of our eye clearly?
Answer:
Yes. By maintaining the 25 cm distance of the object from our eye, we can see the objects in front of our eye.

Question 5.
How do the lenses used in spectacles correct defects of vision?
Answer:
To form image on retina.
To correct
myopia- Concave lens
hypermetropia i- Convex lens

Improve Your Learning

Question 1.
How do you correct the eye defect Myopia? (AS1)
Answer:

• Some people cannot see objects at long distances but can see nearby objects clearly. This type of defect in vision is called ‘Myopia’ or ‘Near sightedness’.
• Myopia is corrected by using a con-cave lens of focal length equal to the distance of the far point F from the eye.
• This lens diverges the parallel rays from distant object as if they are coming from the far point.
• Finally the eye lens forms a clear im-age at the retina.

Question 2.
Explain the correction of the eye defect Hypermetropia. (AS1)
Answer:

• A person with hypermetropia can see distant objects clearly but cannot see objects at near distances. This is also known as ‘far sightedness’.
• Eye lens can form a clear image on the retina when any object is placed beyond near point.
• To correct the defect of hypermetropia, we need to use a lens which forms an image of an object beyond near point at H, when the object is between H and L. This is possible only when a double con¬vex lens is used.
• The image acts like an object for the eye lens. Hence final image due to eye is formed at retina.

Question 3.
How do you find experimentally the refractive index of material of a prism? (AS1)
(OR)
Write the experimental procedure in finding the refractive index of a prism.
(OR)
Which quantity will decide whether a given medium is denser or rarer? How do you find that quantity of prism experimentally?
Answer:
Refractive index decides whether a medium is denser or rarer.
Aim :
To find the refractive index of a prism.

Materials required :
Glass prism, white chart of size 20 x 20 cm, pencil, pins, scale and protractor.

Procedure :

1. Keep a prism on white chart.
2. Draw the triangular base of the prism with pencil.
3. Remove the prism.
4. The shape of the outline drawn prism is triangle and name its vertices as P, Q and R.
5. PQ and PR be the refracting surfaces.
6. Find the angle between PQ and PR. This is the angle of the prism (A) (or) Refracting angle.
7. Mark M on PQ and draw a perpendicular line to PQ at M.
8. Place the centre of the protractor at M, along the normal and mark an angle of 30° and then draw a line up to M. This line denotes incident ray. This angle is called angle of incidence.
9. Place the prism in its position (triangle) again.
10. Now fix two pins vertically on the line at points A and B .
11. See the images of pins through the 2nd refracting side (PR).
12. Fix another two pins at points C and D such that all the four pins appear to lie along the same line.
13. Remove the pins and prism, join the pin-holes. Draw the incident and emergent rays.
14. The angle between the normal and the emergent ray at N is the angle of emergence.
15. The line passing through the points A, B, M, N, C and D represents the path of light when it suffers refraction through prism.

The angle of deviation :

• Extend incident and emergent rays are intercept at a point ‘O’.
• The angle between these two rays is the angle of deviation (d).
• Note the emergent deviation angles for different values of i, in the given table.

• Draw the graph between angle of incidence on X – axis and the angle of deviation on Y – axis.
• We notice that the angle of deviation decreases first and then increases with increase of the angle of incidence.
• Mark points on a graph paper and join the points to obtain a graph (smooth curve).
• Draw a tangent line to the curve, which parallel to X-axis, at the lowest point of the graph.

• The point where this line cuts the Y- axis gives the angle of minimum deviation. It is denoted by D.
• From the graph, we notice that, at angle of minimum deviation, the angle of incidence is equal to the angle of emergence.
• By finding A and D we can find refractive index of prism by using formula .

Question 4.
Explain the formation of rainbow. (AS1)
(OR)
What is the natural spectrum occuring in sky? Explain the formation of that spectrum.
Answer:

• A rainbow is a natural spectrum of sunlight in the form of bows appearing in the sky when the sun shines on rain drops.
• It is combined result of reflection, refraction and dispersion of sunlight from water droplets, in atmosphere.
• It always forms in the direction opposite to the sun.
• To see a rainbow, the sun be must behind us and the water droplets falls in front of us.
• When a sunlight enters a spherical raindrop, it is refracted and dispersed. The different colours of light are bent in different angles.
• When different colours of light falls on the back inner surface of drop, it (Water drop) reflects (different colours of light) interwnally (total internal reflection).
• The water drops again refract the different colours, when it comes out from the raindrop.
• After leaving this different colours from the raindrop as rainbow, reach our eye. Thus, we see a rainbow.

Question 5.
Explain briefly the reason for the blue of the sky. (AS1)
Answer:

• The reason for blue sky is due to the molecules N₂ and O₂.
• The size of these molecules are comparable to the wavelength of blue light.
• These molecules act as scattering centres for scattering of blue light.
• So scattering of blue light by molecules of N₂ and O₂ is responsible for blue of the sky.

Question 6.
Explain two activities for the formation of artificial rainbow. (AS1)
(OR)
Give two activities for the formation of the artificial rainbow? And explain it.
(OR)
Suggest an experiment to create a rainbow in your classroom and explain the procedure.
Answer:
Activity -1 :

• Select a white coated wall on which the sun rays fdll.
• Stand in front of a wall in such a way that the sun rays fall on your back.
• Hold a tube through which water is flowing.
• Place your finger in the tube to obstruct the flow of water.
• Water comes out from small gaps between the tube and finger like a fountain.
• Observe the changes on wall while showering the water.

Activity – II : (Activity – 4)

• Take a metal tray and fill with water.
• Place a mirror in water such that it makes an angle to the water surface.
• Now focus white light on the mirror through the water.
• Keep a white card board sheet above the water surface.
• We may observe the colours VIBGYOR on the board.
• The splitting of white light into different colours (VIBGYOR) is called dispersion.
• So consider a white light is a collection of waves with different wavelengths.
• Violet has shortest wavelength, and red has longest wavelength.

Question 7.
Derive an expression for the refractive index of the material of a prism. (AS1)
Answer:
Derivation of formula for refractive index of a prism :
PQ and PR are refracting surfaces of prism, i, is an angle of incidence, i2 is an angle of emergence, is an angle of refraction of first surface and r2 is an angle of incidence on second surface.

1. From triangle OMN, we get
d = i₁ – r₁ + i₂ – r₂
∴ d = (i₁ + i₂)-(r₁+ r₂) ……… (1)
2. From triangle PMN, we have
∠A + (90° – r₁) + (90° – r₂) = 180°
⇒ r₁ + r₂ = A ……… (2)
3. From (1) and (2),
⇒ d = (i₁ + i₂) – A
⇒ A + d = i₁ + i₂
4. This is the relation between angle of incidence, angle of emergence, angle of deviation and angle of prism.

5. From Snell’s law, we know that
n₁ sin i = n₂ sin r

6. Let ‘n’ be the refractive index of the prism.
7. Using Snell’s law at M, refractive index of air n₁ = 1; i = i₁; n₂ = n; r = r₁.
⇒ sin i₁ = n sin r₁ …………. (4)
8. Similarly, at N, n₁ = n; i = r₂; n₂ = 1; i₁ = i₂
⇒ n sin r₂ = n sin i₂ ………… (5)
9. We know that at the angle of minimum deviation position (D), i.e. i₁ = i₂
10. We will notice that MN is parallel to the base of prism QR.

14. This is the formula for the refractive index of the prism.

Question 8.
Light of wavelength λ₁ enters a medium with refractive index n₂ from a medium with refractive index n₁ What is the wavelength of light in second medium? (AS1)
Answer:
Wavelength of first medium =λ₁
Refractive index of first medium = n₁
Let the wavelength of second medium = λ₂,
Refractive index of second medium = n₂
Light enters from first medium to second medium = \(\Rightarrow \frac{\mathrm{n}_{2}}{\mathrm{n}_{1}}=\frac{\mathrm{c}_{1}}{\mathrm{c}_{2}}=\frac{\lambda_{1}}{\lambda_{2}}\) (∵ υ = const)
\(\Rightarrow \lambda_{2}=\frac{\lambda_{1} \mathrm{n}_{1}}{\mathrm{n}_{2}}\)

Note:
For the below questions the following options are given. Choose the correct option by making hypothesis based on given assertion and reason. Give an explanation.
a) Both A and R are true and R is the correct explanation of A.
b) Both A and R are true and R is not the correct explanation of A.
c) A is true but R is false.
d) Both A and R are false.
e) A is false but R is true.

Question 9.
Assertion (A) : The refractive index of a prism depends only on the kind of glass of which it is made of and the colour of light. (AS2)
Reason (R) : The refractive index of a prism depends on the refracting angle of the prism and the angle of minimum deviation.
Answer:
(b) Both A and R are true and R is not the correct explanation of A.

Question 10.
Assertion (A) : Blue colour of sky appears due to scattering of light.
Reason (R) : Blue colour has shortest wavelength among all colours of white light. (AS2)
Answer:
(C) A is true but R is false.

Question 11.
Suggest an experiment to produce a rainbow in your classroom and explain the procedure. (AS3)
Answer:
Activity to produce a rainbow in classroom :

• Take a prism and place it on the table near a vertical white wall.
• Take a thin wooden plank, make a small hole in it and fix it vertically on the table.
• Place the prism between the wooden plank and wall.
• Place a white light source behind the hole of the wooden plank. Switch on the light.
• Adjust the height of the prism such that the light falls on one of the lateral surfaces.
• Observe the changes in the emerged ray of the prism.
• Adjust the prism by slightly rotating it till you get an image on the wall.
• We observe a band of different colours on the wall.
• These colours are nearly equal to the colours of the rainbow, i.e., VIBGYOR.

Question 12.
Prisms are used in binoculars. Collect information why prisms are used in binoculars. (AS4)
Answer:

• Binoculars consists of a pair of identical or mirror symmetrical telescope mounted side by side and aligned to point accurately in the same direction, allowing the viewer to use both eyes, when viewing distant objects.
• The size of binoculars is reduced by using prisms.
• We get good image with more brightness.
• Objective size and optical quality should be increased by using prisms in binoculars.

Question 13.
Incident ray on one of the face (AB) of prism and emergent ray from the face AC are given in figure. Complete the ray diagram. (AS5)

Answer:

Question 14.
How do you appreciate the role of molecules in the atmosphere for the blue colour of the sky? (AS6)
(OR)
How do you appreciate the nature of molecules, responsible for the blue of the sky?
Answer:

• The sky appear blue due to atmospheric refraction and scattering of light through molecules.
• Molecules are scattering centres.
• The reason to blue sky is due to the molecules N2 and 02.
• The sizes of these molecules are comparable to the wavelength of blue light.
• In the absence of molecules there will be no scattering of sunlight and the sky will appear dark.
• We should appreciate the molecules which are scattering centres.

Question 15.
Eye is the only organ to visualise the colourful world around us. This is possible due to accommodation of eye lens. Prepare a six line stanza expressing your wonderful feelings. (AS6)
Answer:
“Many people simply see
The world in black and white
But through my eyes the world’s alive
So colourful and bright
Don’t close your mind to the sights
That light up the night and day
There’s so much to see here on this earth
And not a rupee do you have to pay”
The most obvious things aren’t the ones
There is beauty in the unknown
with willing eyes and an open mind
The true wonders you will be shown

Question 16.
How do you appreciate the working of ciliary muscles in the eye? (AS6)
(OR)
Which muscles are helpful in changing the focal length of eye lens? How do you appreciate those muscles?
Answer:

• Ciliary muscles are helpful in changing focal length of eye lens.
• The ciliary muscles which attached with eye lens help to change the focal length of eye lens.
• When the eye is focussed on a distant object, these are relaxed. So the focal length of eye lens increases to its maximum value.
• The parallel rays coming into the eye are focussed on the retina then we can see the object clearly.
• When the eye is focussed on a nearer object the muscles are strained so the focal length of eye-lens decreases. The ciliary muscles adjust the focal length and the image is formed on retina then we can see the object.
• Their process of adjusting focal length of eve lens is called accomodation.
• So ciliary muscles must be appreciated for its accomodation of eye lens.

Question 17.
Why does the sky sometimes appear white? (AS7)
(OR)
The sky sometimes appears white. What is the reason behind it?
Answer:

• Our atmosphere contains atoms and molecules of different sizes.
• According to their sizes, they are able to scatter different wavelengths of light.
• For example, the size of the water molecule is greater than the size of the N₂ or O₂.
• It acts as a scattering centre for light other frequencies which are lower than the frequency of blue light.
• On a hot day due to rise in the temperature, water vapour enters atmosphere which leads to abundant presence of water molecules in atmosphere. These water molecules scatter the colours of other frequencies (other than blue).
• All such colours of other frequencies reach our eye and white colour is appeared to us.

Question 18.
Glass is known to be transparent material. But ground glass is opaque and white in colour. Why? (AS7)
Answer:

• Ground glass is glass whose surface has been ground that produces a flat but rough finish.
• Ground glass has the effect of rendering the glass translucent by scattering of light during transmission thus blurring visibility while still transmitting light.
• To get more permanent frost, the glass may be ground by rubbing with some gritty substance.

Question 19.
If a white sheet of paper is stained with oil, the paper turns transparent. Why? (AS7)
(OR)
What is the reason behind the paper turns transparent when it is immersed in oil?
Answer:

• The paper fibres have higher index of refraction probably much greater than 1.5.
• The oil or fat also has a high index of refraction so that it nearly matches the index of refraction of the paper fibres and it reduces the scattering significantly.
• The fat adhering to the cellulose fibers lowers the index of refraction of the cellulose and also fills in air voids, so that visible light passes through the bag with significantly less scattering.
• The oil connects the fibres in the paper with a liquid which can transmit by refraction (rather than scatter) light that falls upon it. As a result, the paper stained with oil is turned transparent.

Question 20.
A light ray falls on one of the faces of a prism at an angle 40° so that it suffers angle of minimum deviation of 30°. Find the angle of prism and angle of refraction at the given surface. (AS7)
Answer:
Given that, incident ray on one of the prisms (i₁) = 40°
Angle of minimum deviation (D) = 30°
Angle of prism (A) = ?
A+D = 2i₁
⇒ A = 2i₁ – D
⇒ A = 2(40°) -30°
= 80° – 30°
= 50°
∴ Angle of prims (A) = 50°
Angle of refraction (r₁) = ?

Question 21.
The focal length of a lens suggested to a person with Hypermetropia is 100 cm. Find the distance of near point and power of the lens. (AS7)
Answer:
i) The distance of near point :
If the distance of near point is ‘d’ and focal length is ‘f’ then the relation between

Question 22.
A person is viewing an extended object. If a converging lens is placed in front of his eye, will he feel that the size of object has increased? Why? (AS7)
Answer:

• A simple magnifier allows us to put the object closer to the eye than we could normally focus and forms an enlarged virtual images.
• The principle behind this is angular magnification.
• The magnification is Ma = \(\frac{25}{f}\) for the close focus point, but since that causes eye strain, it is usually desirable to put the images at infinity giving Ma = \(\frac{25}{f}\)
• So he fees the size of object is increased. The reason is mentioned.
• Angular magnification: ‘The ratio of the angle substended at the eye by the image formed by an optical instrument to the angle substended at the eye by the object being viewed.”

Fill In The Blanks

1. The value of least distance of distinct vision is about ……………………… .
2. The distance between the eye lens and retina is about ……………………… .
3. The maximum focal length of the eye lens is about ……………………… .
4. The eye lens can change its focal length due to working of ……………………… muscles.
5. The power of lens is ID then focal length is ……………………… .
6. Myopia can be corrected by using ……………………… lens.
7. Hypermetropia can be corrected by using ……………………… lens.
8. In minimum deviation position of prism, the angle of incidence is equal to angle of ……………………… .
9. The splitting of white light into different colours (VIBGYOR) is called ……………………… .
10. During refraction of light, the character of light which does not change is ……………………… .
Answer:

1. 25 cm
2. 2.5 cm
3. 2.5 cm
4. ciliary
5. 100 cm
6. bi-concave
7. bi-convex
8. emergence
9. dispersion of light
10. frequency

Multiple Choice Questions

1. The size of an object as perceived by an eye depends primarily on
A) actual size of the object
B) distance of the object from the eye
C) aperture of the pupil
D) size if the image formed on the retina
Answer:
B) distance of the object from the eye

2. When objects at different distances are seen by the eye which of the following remains constant?
A) focal length of eye-lens
B) object distance from eye-lens
C) the radii of curvature of eye-lens
D) image distance from eye-lens
Answer:
D) image distance from eye-lens

3. During refraction, …………….. will not change.
A) wavelength
B) frequency
C) speed of light
D) all the above
Answer:
B) frequency

4. A ray of light falls on one of the lateral surfaces of an equilateral glass prism placed on the horizontal surface of a table as shown in figure. For minimum deviation of ray, which of the following is true?

A) PQ is horizontal
B) ‘QR’ is horizontal
C) ‘RS’ is horizontal
D) Either ‘PQ’ or ‘RS’ is horizontal
Answer:
B) ‘QR’ is horizontal

5. Far point of a person is 5 m. In order that he has normal vision what ki nd of spectacles should he use?
A) concave lens with focal length 5 m
B) concave lens with focal length 10 m
C) convex lens with focal length 5 m
D) convex lens with focal length 2.5 mm
Answer:
A) concave lens with focal length 5 m

6. The process of re-emission of absorbed light in all directions with different intensi¬ties by the atom or molecule is called ……………
A) scattering of light
B) dispersion of light
C) reflection of light
D) refraction of light
Answer:
A) scattering of light

10th Class Physics 7th Lesson Human Eye and Colourful World InText Questions and Answers

10th Class Physics Textbook Page No. 104

Question 1.
Can you imagine the shape of rainbow when observed during travel in an airplane?
Answer:

The shape of rainbow, when observed during travel in an airplane is circular as shown in the following figure.

10th Class Physics Textbook Page No. 88

Question 2.
Why do the values of least distance of distinct vision and angle of vision change with person and age?
Answer:

• The ciliary muscle helps the eye lens to change its focal length by changing radii of curvature of eye lens.
• When the eye is focussed on a distant object, the ciliary muscles are relaxed so that the focal length of eye lens has its maximum value which is equal to its distance from the retina.
• The working of ciliary muscle in eye changes from person to person.
• So, the values of least distance of distinct vision and angle of vision changes with person and age.

10th Class Physics Textbook Page No. 89

Question 3.
How can we get same image distance for various positions of objects?
Answer:
For different positions of object, the image distance remains constant only when focal length of lens changes.

Question 4.
Can you answer above question using concepts of refraction through lenses?
Answer:
The focal length of a lens depends on the material by which it has been made and radii of curvatures of lens. We need to change focal length of eye lens to get same image distance for various positions of object.

10th Class Physics Textbook Page No. 90

Question 5.
How does eye lens change its focal length?
(OR)
What is the role of ciliary muscles in the eye ? Write the answer in one or two sentences only.
Answer:
The ciliary muscles to which eye lens is attached help the eye lens to change its focal length by changing the radii of curvature of eye lens.

Question 6.
How does this change (eye lens changes its focal lengths) take place in eye ball?
Answer:
When the eye is focussed on a distant object the ciliary muscles are relaxed. So the focal length of eye lens has its maximum value which is equal to its distance from the retina. The parallel rays coming into the eye are then focussed on to the retina and we see the object clearly.

Question 7.
Does eye lens form a real image or virtual image?
Answer:
The eye lens forms a real and inverted image of an object on the retina.

Question 8.
How does the image formed on retina help us to perceive the object without change in its shape, size and colour?
Answer:

• The eye lens forms a real and inverted image of an object on the retina.
• This retina is a delicate membrane, which contains large number of receptors (125 million) called ‘rods’ and ‘cones’.
• They receive the light signals and identify the colour, and the intensity of light.
• These signals are transmitted to the brain through optic-nerve fibres.
• The brain interprets these signals and finally processes the information so that we perceive the object in terms of its shape, size and colour.

Question 9.
Is there any limit to change of focal length of eye lens?
Answer:
Yes. When the object is at infinity, the parallel rays from the object falling on the eye lens are refracted. They form a point-sized image on retina. In this situation, eye lens has a maximum focal length.

Question 10.
What are the maximum and minimum focal lengths of the eye lens?
Answer:
Maximum focal length is 2.5 cm and minimum focal length is 2.27 cm.

Question 11.
How can we find the maximum and minimum focal lengths of the eye lens?
(OR)
Calculate the maximum and minimum focal lengths of the eye lens.
Answer:’
a) When the object is at infinity,
u = – ∞ ; v = 2.5 cm (image distance which is equal to distance between eye lens and retina)

b) Object at a distance of 25 cm from eye. In this case, eye has minimum focal length.
Here u = -25 cm ; v 2.5 cm

10th Class Physics Textbook Page No. 91

Question 12.
What happens if eye lens is not able to adjust its focal length?
Answer:
In this case the person cannot see the object clearly and comfortably.

Question 13.
What happens if the focal length of eye lens is beyond the range of 2.5 cm to 2.27 cm?
Answer:
The vision (image) becomes blurred due to defects of eye lens.

10th Class Physics Textbook Page No. 92

Question 14.
What can we do to correct myopia?
Answer:
To correct myopia, we use concave lens.

10th Class Physics Textbook Page No. 93

Question 15.
How can you decide the focal length of the lens to be used to correct myopia?
Answer:
Assume that the object distance (u) is infinity and image distance (v) is equal to distance of far point.
u = – ∞ ; v = distance of far point = – D
Let ‘f be the focal length of bi-concave lens.

Here ‘f is negative showing that it is a concave lens.

Question 16.
What happens when the eye has a minimum focal length greater than 2.27 cm?
Answer:
In this case, the rays coming from the nearby object after refraction at eye lens, forms image beyond the retina.

10th Class Physics Textbook Page No. 94

Question 17.
How can you decide the focal length of convex lens to be used?
Answer:
Here object distance (u) = -25 cm
Image distance (v) = – d (distance of near point)
Let ‘f be the focal length of bi-convex lens.

If d > 25 cm, then ‘f’ becomes positive then we need to use bi-convex lens to correct hypermetropia.

10th Class Physics Textbook Page No. 95

Question 18.
Have you ever observed details in the prescription?
Answer:
A prescription that contains some information regarding type of lens to be used to correct vision.

Question 19.
What does it (“my sight is increased or decreased”) mean?
Answer:
Usually doctors, after testing the defects of vision prescribe corrective lenses indicating
their power which determines the type of lens to be used and its focal length.

Question 20.
What do you mean by power of lens ? flftorH)
Answer:
The reciprocal of focal length is called power of lens.

Question 21.
Doctor advised to use 2D lens. What is its focal length?
Answer:
Given power of lens P = 2D

∴ Focal length of lens (f) = 50 cm.

10th Class Physics Textbook Page No. 96

Question 22.
How could the white light of the sun give us various colours of the rainbow?
Answer:
Due to reflection, refraction and dispersion of sunlight.

Question 23.
What happens to a light ray when it passes through a transparent medium bounded by plane surfaces which are inclined to each other?
Answer:
When light incident on one of the plane surfaces and emerges from the other.

Question 24.
What is a prism?
Answer:
A prism is a transparent medium separated from the surrounding medium by consisting two refracting plane surfaces which are inclined.

10th Class Physics Textbook Page No. 97

Question 25.
What is the shape of the outline drawn for a prism?
Answer:
The outline drawn for a prism is in a triangle shape.

10th Class Physics Textbook Page No. 98

Question 26.
How do you find the angle of deviation?
Answer:
The angle between the extended incident and emergent rays is called angle of deviation.
(OR)
Extend both incident and emergent rays till they meet at a point ‘O’. Measure the angle between these two rays. This is the angle of deviation.

Question 27.
What do you notice from the angle of deviation?
Answer:
The angle of deviation decreases first and then increases with increase in the angle of incidence.

Question 28.
Can you draw a graph between angle of incidence and angle of deviation?
Answer:

Yes, we can draw the graph between angle of incidence and angle of deviation.

Question 29.
From the graph, can you find the minimum of the angle of deviation?
Answer:
Yes, we can. Draw a tangent line to the curve, parallel to X – axis, at the lowest point of the graph. The point where this line cuts Y – axis gives the angle of minimum deviation.

Question 30.
Is there any relation between the angle of incidence (i) angle of emergence (r) and piangle of deviation (d)?
Answer:
(i₁ + i₂)= A + D
i + r = A + D

10th Class Physics Textbook Page No. 101

Question 31.
In activity-3,we noticed that light has chosen different paths. Does this mean that the refractive index of the prism varies from colour to colour?
Answer:
Yes, refractive index of the prism varies from colour to colour.

Question 32.
Is the speed of light of each colour different?
Answer:
In vacuum – No, the speed of each colour is constant.
In medium – Speed is different for different colours.

Question 33.
Can you guess now, why light splits into different colours when it passes through a prism?
Answer:
Due to dispersion of light and different wavelength of colours in medium.

10th Class Physics Textbook Page No. 102

Question 34.
Does it (light passing through a prism) split into more colours? Why?
Answer:
We know the frequency of light is the properly of the source and it is equal to number of waves leaving the source per second. This cannot be changed by any medium. Hence frequency doesn’t change due to refraction. The coloured light passing through any transparent medium retains its colour.

Question 35.
Can you give an example in nature, where you observe colours as seen in activity 3?
Answer:
Yes, in rainbow. It is a good example of dispersion of light.

Question 36.
When do you see a rainbow in the sky?
Answer:
Dut to the refraction, reflection and dispersion of sunlight, when the sunlight passes through the rain drops, we can see the rainbow in the sky.

Question 37.
Can we create a rainbow artificially?
Answer:
Yes, we can create a rainbow artificially.

10th Class Physics Textbook Page No. 104

Question 38.
Why does the light dispersed by the raindrops appear as a bow?
Answer:

• A rainbow is not the flat two dimensional arc as it appears to us.
• The rainbow we see is actually a three dimensional cone with the tip of our eye.
• All the drops that disperse the light towards us lie in the shape of the cone – a cone of different layers.
• The drops that disperse red colour to our eye are on the outermost layer of the cone, similarly, the drops that disperse orange colour to our eye are on the layer of the cone beneath the red colour cone.
• In this way the cone responsible for yellow lies beneath orange and so on it till the violet colour cone becomes the innermost cone.

Question 39.
Why is the sky blue?
Answer:
A clear cloudless day – time sky is blue because molecules in the air scatter blue light from the sun more than thev scatter red liuht.

Question 40.
What is scattering?
A. Atoms or molecules which are exposed to absorb light energy and emit some part of the light energy in different directions is called scattering of light.

10th Class Physics Textbook Page No. 106

Question 41.
Why is that the sky appears white sometimes when you view it in certain direction on hot days?
Answer:

• On a hot day, due to rise in the temperature, water vapour enters atmosphere which leads to abundant presence of water molecules in atmosphere.
• These water molecules scatter the colours of other frequencies (other than blue).
• All such colours of other frequencies reach our eye and the sky appears white.

Question 42.
Do you know the reasons for appearance the red colour of sun during sunrise and at sunset?
(OR)
Sun appears red in colour during sunrise and sunset. Give reason.
(OR)
Why does sky appear red at Sunshine and Sunset?
Answer:

• The light rays from the sun travel more distance in atmosphere to reach our eye in morning and evening times.
• During sunrise and sunset except red light all colours scatter more and vanish before they reach us.
• Since scattering of red light is very less, it reaches us.
• As a result sun appears red in colour during sunrise and sunset.

Question 43.
Can you guess the reason why sun does not appear red during noon hours?
Answer:
During noon hours, the distance to be travelled by the sun rays in atmosphere is less than when compared to morning and evening hours. Therefore all colours reach our eye without scattering. Hence the sunlight appears white in noon hours.

10th Class Physics 7th Lesson Human Eye and Colourful World Activities

Activity – 1

Question 1.
How do you find least distance of distinct vision?
(OR)
What is the least distance a person can see an object comfortably and distinctly known as ? Write an activity to find that (least, distance of distinct vision) distance.
Answer:

• The least distance a person can see an object comfortably and distinctly is known as least distance of distinct vision.
• Hold the textbook at certain distance with your hands.
• Try to read the contents on the page.
• Gradually move the book towards eye, till it reaches very close to your eyes.
• You may see that printed letters on the page appear blurred or you feel strain to read.
• Now move the book backwards to a position where you can see clear printed letters without strain.
• Ask your friend to measure distance between your eye and textbook at this position.
• Note down its value.
• Repeat this activity with other friends and note down the distances for distinct vision in each case.
• Find the average of all these distances of clear vision.
• You will notice that to see an object comfortably and distinctly, you must hold it at a distance about 25 cm from your eyes.
• This 25 cm distance is called least distance of distinct vision.
• This value varies from person to person and with age.

Activity – 2

Question 2.
How can you find angle of vision?
(OR)
What is maximun angle a person is able to see whole object? Write an activity to find that angle.
Answer:

• The maximum angle, at which we are able to see the whole object is called angle of vision.
• Arrange a retort stand.
• Collect a few wooden sticks (or) PVC pipes that are used for electric wiring.
• Prepare sticks or pipes of 20 cm, 30 cm, 35 cm, 40 cm, 50 cm from them.
• Keep the retort stand on a table and stand near the table such that vour head is beside the vertical stand.
• Adjust the clamp on horizontal rod and fix at a distance of 25 cm from the eyes.
• Ask one of your friends to fix a wooden stick of 30 cm height to the clamp in vertical position.
• Now keeping your vision parallel to horizontal rod of the stand, try to see the top and bottom of wooden stick kept in vertical position.
• If you are not able to see both ends of stick at this distance (25 cm), adjust the vertical stick on the horizontal rod till you are able to see both ends of the stick at nearest possible distance from your eye.
• Fix the clamp to the vertical stick at this position.
• Without changing the position of the clamp on horizontal rod, replace this stick of 30 cm length.
• Try to see the top and bottom of the stick simultaneously without any change in the position of eye.
• Try the same activity with various lengths of the sticks.
• You can see the whole object AB which is at a distance of 25 cm (least distance of clear vision) because the rays coming from the ends A and B of the object will enter the eye.
• Similarly we can also see complete object CD with eye as explained above.
• Let us assume that AB is moving closer to eye to a position A B .
• You notice that you will be able to see only the part (EF) of the object A B because the rays coming from E and F enter your eye.

• The rays coming from A and B cannot enter your eye.
• The rays coming from the extreme ends of an object forms an angle at the eye.
• If this angle is below 60°, we can see whole object.
• If this angle is above 60°, then we see only the part of the object.
• This maximum angle, at which we are able to see the whole object is called angle of vision.
• The angle of vision for a healthy human being is about 60°.
• It varies from person to person and with age.

Activity – 3

Question 3.
Describe an activity for dispersion of light.
(OR)
What is the name given to process when white light passes through a prism it splits into different colours ? Explain the process with an activity.
Answer:

• The splitting of white light into different colours is called despersion of light.
• Do this experiment in the dark room.
• Take a prism and place it on the table near a vertical white wall.
• Take a thin wooden plank.
• Make a small hole in it and fix it vertically on the table.
• Place the prism between the wooden plank and wall.
• Place a white light source behind the hole of wooden plank.
• Switch on the light.
• The rays coming out of the hole of plank become a narrow beam of light.
• Adjust the height of the prism such that the light falls on one of the lateral surfaces.
• Observe the changes in emerged rays of the prism.
• Adjust the prism by slightly rotating it till you get an image on the wall.
• You will observe that white light is splitting into certain different colours.

Activity – 6

Question 4.
Describe an experiment for scattering of light.
(OR)
What is the principle involved in blue of the sky ? Explain the principle with an experiment?
Answer:

• Take the solution of sodium-thio-Sulphate (hypo) with sulphuric acid in a glass beaker.
• Place the beaker in which reaction is taking place in an open place where abundant sunlight is available.
• Watch the formation of grains of sulphur and observe changes in beaker.
• You will notice that sulphur precipitates as the reaction is in progress.
• At the beginning, the grains of sulphur are smaller in size as the reaction progresses, their size increases due to precipitation.
• Sulphur grains appear blue in colour at beginning and slowly their colour becomes white as their size increases.
• The reason for this is scattering of light.
• At the beginning, the size of grains is small and almost comparable to the wavelength of blue light.
• Hence they appear blue in the beginning.
• As the size of grains increases, their size becomes comparable to the wavelengths of other colours.
• As a result of this, they act as scattering centres for other colours.
• The combination of all these colours appears as white.

AP State Board Syllabus AP SSC 10th Class Chemistry Solutions Chapter 9 Classification of Elements- The Periodic Table Textbook Questions and Answers.

AP State Syllabus SSC 10th Class Chemistry Solutions 9th Lesson Structure of Atom

10th Class Chemistry 9th Lesson Structure of Atom Textbook Questions and Answers

Improve Your Learning

Question 1.
Newlands proposed the law of octaves. Mendeleeff suggested eight groups for elements in his table. How do you explain these observations in terms of modem periodic classification? (AS1)
(OR)
Correlate various tables proposed on classification of elements.
Answer:

• According to Newlands, every eighth element starting from a given element jsembles in its properties to that of the starting element, when elements are ranged in ascending order of their atomic weights.
• According to Newlands, the properties of fluorine and chlorine are similar and sodium and potassium are similar. Same aspect is given by modern periodic table.
• Mendeleeff divided it into horizontal rows and vertical columns. He called them peribds and groups respectively. Modem periodic table also gives the same.
• According to Mendeleeff, the elements of same group have similar properties. Modern periodic table also proposed the same thing.
• Mendeleeff gave the general formula for first group elements as R,0, and general formula for second group elements as RO. We can find the same thing in modern periodic table.
• The elements of particular group possess same common valency. Same was proposed by modern periodic table.

Question 2.
What are the limitations of Mendeleeff’s periodic table? How could the modern periodic table overcome the limitations of Mendeleeff’s table? (AS1)
(OR)
How can the limitations of Mendeleeffs table be overcome with the help of modern periodic table?
Answer:
Limitations of Mendeleeffs periodic table :
1) Anomalous pair of elements :
Certain elements of highest atomic weights precede those with lower atomic weights.
Eg : Tellurium (atomic weight 127.6) precedes iodine (atomic weight 126.9).

2) Dissimilar elements placed together :
a) Elements with dissimilar properties were placed in same group as sub-group A and sub-group Bt
Eg : Alkali metals like Li, Na, K, etc. of IA group have little resemblance with coinage metals like Cu, Ag, Au of IB group.

b) Cl of VII A group is a non-metal and Mn of VII B group is a metal.

Method of overcoming the limitations of Mendeleeffs periodic table by modern periodic table :
1. In modern periodic table, elements are arranged in the ascending order of their atomic numbers. So this arrangement eliminated the problem of anomalous series.
Eg : Though Tellurium (Te) has more atomic weight than Iodine (I), its atomic number is one unit less compared to Iodine.

2. The elements with similar outer shell (valence shell) electronic configurations in their atoms are in the same column called group in modern periodic table. So the elements have similar properties overcoming the Mendeleeffs second limitation.

Question 3.
Define the modern periodic law. Discuss the construction of the long form of the periodic table. (AS1)
(OR)
What are the salient features of modern periodic table?
Answer:
Modern periodic law :
‘The physical and chemical properties of elements are the periodic function of the electronic configurations of their atoms”.

Construction of the long form periodic table :

1. Based on the modern periodic law, the modern periodic table is proposed.
2. This periodic table is known as long form of the periodic table.
3. Long form periodic table is the graphical representation of Aufbau principle.
4. The modern periodic table has 18 vertical columns called groups and 7 horizontal rows known as periods.
5. There are 18 groups, represented by using Roman numerals I to VIII, with letters A and B in traditional notation, (or) 1 to 18 by Arabic numerals.
6. There are 7 periods. These periods are represented by Arabic numerals 1 to 7.
7. The number of main shells present in the atom of particular atom decides to which period it belongs.
8. First period consists 2 elements, 2^nd and 3rd periods contains 8 elements each, 4^th and 5^th periods contains 18 elements each, 6 period contains 32 elements and 7^th period is incomplete.
9. The elements are classified into s, p, d and f block elements.
10. Inert gases are placed in 18^th group.

Question 4.
Explain how the elements are classified into s, p, d and f-block elements in the periodic table and give the advantage of this kind of classification. (AS1)
(OR)
How is the periodic table classified based upon the entering of differenciating electron? Explain that classification. What is the advantage of such classification?
Answer:
1) Depending upon which sub-shell the differentiating electron enters, the elements are classified into s, p, d and f-block elements. They are

1. s – block elements,
2. p – block elements,
3. d – block elements,
4. f – block elements.

2) s – block elements :
i) If the differentiating electron enters in s-sub-shell, then the elements are called s-block elements.
ii) IA (1), IIA (2) group elements belong to this block.

3) p – block elements :
i) If the differentiating electron enters in p-sub-shell, then the elements are called p-block elements.
ii) IIIA(13), IV A (14), V A (15), VIA (16), VIIA (17) belong to p-block.

4) d – block elements :
i) If the differentiating electron enters in d-sub-shell, then the elements are called d – block elements.
ii) I B, II B, III B, IV B, V B, VI B, VII B, VIII B belong to d-block elements.
iii) They are also called transition elements.

5) f – block elements :
i) If the differentiating electrons enter in f-sub-shell, then the elements are called f-block elements.
ii) These are divided into two types
a) Lanthanides (41 elements),
b) Actinides (5f elements).
iii) These are also called as inner transition elements.

Advantage of this classification :
1) The systematic grouping of elements into groups made the study simple.
2) Each period begins with the electron entering a new shell and ends with the complete filling of s and p-sub-shells of that shell.

Question 5.
Given below is the electronic configuration of elements A, B, C, D. (AS1)

Answer:
According to electronic configuration
A = Be B = Mg C = P D = Ne
1. Which are the elements coming within the same period?
Answer:
A and D i.e. Be and Ne coming within the same period. [They have same valence shell (n = 2)]

2. Which are the ones coming within the same group?
Answer:
A and B i.e., Be and Mg coming within the same group. [They have same valence subshell with same valency (2s² and 3s²)]

3. Which are the noble gas elements?
Answer:
D, i.e. Ne is the noble gas element. [It has valency as ‘O’ and it has ‘8’ electrons in valence shell].

4. To which group and period does the element ‘C’ belong?
Answer:
Element ‘C’ i.e. ‘P’ belongs to 3^rd period and VA group.

Question 6.
Write down the characteristics of the elements having atomic number 17. (AS1)
1) Electronic configuration ___________
2) Period number _____________
3) Group number _____________
4) Element family ____________
5) No. of valence electrons ___________
6) Valency _____________
7) Metal or non-metal ____________
Answer:

1. 1s² 2s² 2p⁶ 3s² 3p⁵
2. 3
3. VII A or 17
4. Halogen family
5. 7
6. 1
7. Non-metal

Question 7.
a) State the number of valence electrons, the group number and the period number of each element given in the following table : (AS1)

Answer:

b) State whether the following elements belong to a Group (G), Period (P) or neither Group nor Period (N). (AS1)

Answer:

Question 8.
Elements in a group generally possess similar properties, but elements along a period have different properties. How do you explain this statement? (AS1)
(OR)
Elements in a group possess similar properties, but elements along a period have different properties. Explain the reason.
Answer:

• Physical and chemical properties of elements are related to their electronic configurations, particularly the outer shell configurations.
• Therefore, all the elements in a group should have similar chemical properties.
• Similarly, across the table from left to right in any period, elements get an increase in the atomic number by one unit between any two successive elements.
• Therefore, the electronic configuration of valence shell of any two elements in a period is not same. Due to this reason, elements along a period possess different chemical properties.

Question 9.
s – block and p – block elements except 18^th group elements are sometimes called as ‘Representative elements’ based on their abundant availability in the nature. Is it justified? Why? (AS1)
(OR)
Which elements are called representative elements? Why?
Answer:

• s, p – block elements are called representative elements because these are the elements which take part in chemical reactions because of incompletely filled outermost shell.
• These elements undergo chemical reactions to acquire the nearest noble gas configuration by losing or gaining or sharing of electrons.
• So they are called representative elements.

Question 10.
Complete the following table using periodic table. (AS1)

Answer:

Question 11.
Complete the following table using the periodic table. (AS1)

Answer:

Question 12.
The electronic configuration of the elements X, Y, and Z are given below.
a) X = 2
b) Y = 2, 6
c) Z = 2, 8, 2
i) Which element belongs to second period?
Answer:
Y belongs to second period.

ii) Which element belongs to second group?
Answer:
Z belongs to second group,

iii) Which element belongs to 18^th group?
Answer:
X belongs to 18^th group.

Question 13.
Identify the element that has the larger atomic radius in each pair of the following and mark it with a symbol (✓). (AS1)
(i) Mg or Ca
(ii) Li or Cs
(iii) N or P
(iv) B or Al
Answer:

Question 14.
Identify the element that has the lower ionization energy in each pair of the, following and mark it with a symbol (✓). (AS1)
(i) Mg or Na (ii) Li or O (iii) Br or F (iv) K or Br
Answer:

Question 15.
In period 2, element X is to the right of element Y. Then, find which ofitheydements have : (AS1)
i) Low nuclear charge
Answer:
Y has low nuclear charge.

ii) Low atomic size
Answer:
X has lower atomic size,

iii) High ionization energy
Answer:
X has higher ionization energy.

iv) High electronegativity
Answer:
Xhas high electronega^vity.

v) More metallic,character
Answer:
Y has more metallic character.

Question 16.
How does metallic character change when we move
i) Down a group?
ii) Across a period?
Answer:
i) Down a group :
When we move from top to bottom in a group, the metallic character increases.

ii) Across a period:
When we move left to right in a period, the metallic character decreases.

Question 17.
Why was the basis of classification of elements changed from the atomic mass to the atomic number? (AS1)
(OR)
Which atomic property is more suitable for classification of elements? Why?
Answer:

• The first attempt to classify elements was made by Dobereiner.
• Dobereiner’s attempt gave a clue that atomic masses could be correlated with properties of elements:
• Newlands’ law of octaves also followed the same basis for classification but this law is not valid for the elements that had atomic masses higher than calcium.
• Mendeleeff’s classification also based on the atomic masses of elements, but it lead to some limitations like Anomalous pair of elements and Dissimilar elements placed together.
• Moseley by analyzing the X-ray patterns of different elements was able to calculate the number of positive charges in the atoms of respective elements.
• With this analysis, Moseley realized that the atomic number is more fundamental
  characteristic of an element than its atomic weight. ,
• So, he arranged the elements in the periodic table according to the increasing order of their atomic number.
• This arrangement eliminated the problem of anomalous series and dissimilar elements placed together in Mendeleeff’s classification.

Question 18.
What is a periodic property? How do the following properties change in a group and period? Explain. (AS1)
I. a) Atomic radius
b) Ionization energy
c) Electron affinity
d) Electronegativity
II. Explain the ionization energy order in the following sets of elements: (AS1)
a) Na, Al, Cl
b) Li, Be, B
c) C, N, O
d) F, Ne, Na
e) Be, Mg, Ca
Answer:
Periodic property:
The property in which there shall be a regular gradation is called periodic property.

I. a) Atomic radius :
Period :
Atomic radius of elements decreases across a period from left to right because the nuclear charge increases due to increase in atomic number.

Group :
Atomic radius increases from top to bottom in a group due to addition of new shell.

b) Ionization energy:
Period :
When we move from left to right it does not follow a regular trend but generally increases due to increase in atomic number.

Group :
In a group from top to bottom, the ionization energy decreases due to increase in atomic size. –

c) Electron affinity:
Period :
Electron affinity values increase from left to right in a period.

Group :
Electron affinity values decrease from top to bottom in a group.

d) Electronegativity :
Period :
Electronegativity increases from left to right in a period.

Group :
Electronegativity decreases from top to bottom in a group.

II. Ionization energy order :
a) Na, Al, Cl
b) Li, Be, B
c) C, N, O
d) F, Ne, Na
e) Be, Mg, Ca
Answer:
a) In a period ionisation energy increases so the order is Na < kl < Cl.
b) Beryllium has stable configuration 1s² 2s². So it has more ionisation energy. So the order is Li < B < Be.
c) Nitrogen has half-filled p-orbitals. So it has greater ionisation energy. So the order is C < O < N.
d) Ne is inert gas right to F. Whereas Na is a metal ion in third period. So, the order is Na < F < Ne. e) In a group ionisation energy decreases. So the order is Be > Mg > Ca.

Question 19.
Name two elements that you would expect to have chemical properties similar to Mg. What is the basis for your choice? (AS2)
Answer:

• The two elements which have chemical properties similar to Magnesium are Beryllium and Calcium.
• The basis for my expectation is that they belong to same group as we know elements belonging to same group have similar properties.

Question 20.
On the basis of atomic numbers predict to which block the elements with atomic number 9, 37, 46 and 64 belong to? (AS2)
Answer:

1. The element with atomic number 9 belongs to p-block.
2. The element with atomic number 37 belongs to s-block.
3. The element with atomic number 46 belongs to d-block.
4. The element with atomic number 64 belongs to f-block.

Question 21.
Using the periodic table, predict the formula of compound formed between and element X of group 13 and another element Y of group 16. (AS2)
Answer:
The valency of 13^th group elements is 3.
The valency of 16^th group elements is 2.
The formula of compound is X₂Y₃.

Question 22.
An element X belongs to 3rd period and group 2 of the periodic table. State (AS2)
a) The no. of valence electrons
b) The valency.
c) Whether it is metal or a non-metal.
Answer:
a) The number of valence electrons are 2.
b) The valency of element is +2.
c) It is a metal.

Question 23.
An element has atomic number 19. Where would you expect this element in the periodic table and why? (AS2)
Answer:
The clement with atomic number 19 is in 4^th period and first group of the periodic table.
Reason :

1. Electronic configuration : 1s² 2s² 2p⁶ 3s² 3p⁶ 4s or [Ar]4s¹
2. The differentiating electron enters into 4^th shell. Hence it belongs to 4^th period.
3. The differentiating electron is in ‘s’ orbital. So it belongs to ‘s’ block.
4. The outermost orbital has only one electron. Hence it belongs to first group.

Question 24.
Aluminium does not react with water at room temperature but reacts with both dil. HCl and NaOH solutions. Verify these statements experimentally. Write your observations with chemical equations. From these observations, can we conclude that Al is a metalloid? (AS3)
Answer:

• Aluminium reacts with dil. HCl and releases hydrogen gas with formation of Aluminium chloride.
  
• Aluminium reacts with NaOH solution and releases hydrogen gas.
• 
• The above two reactions says that Aluminium is amphoteric.
• Aluminium does not react with water at room temperature.
• This concludes that the properties of Aluminium are in between a metal and non¬metal. So it behaves like a metalloid.

Question 25.
Collect the information about reactivity of VIIIA group elements (noble gases) from internet or from your school library and prepare a report on their special character when compared to other elements of periodic table. (AS4)
Answer:
Reactivity of Noble gases :

• The noble gases show extremely low chemical reactivity.
• He and Ne do not form chemical compounds.
• Xenon, krypton and argon show only minor reactivity.
• The reactivity order follows like this : Ne < He < Ar < Kr < Xe < Rn.
• Xenon can form compounds like XeF₂, XeF₄ and XeF₆, etc.

Reasons for low reactivity :

• The extremely low reactivity of noble gases is due to stable electronic configuration.
• But as we move from top to bottom the reactivity increases. So xenon can form some compounds with high electronegative elements.

Question 26.
Collect information regarding metallic character of elements of IA group and prepare report to support the idea of metallic character increases in a group as we move from top ro bottom. (AS4)
Answer:
Metallic character of IA group elements :

1. Alkali metals exhibit many of the physical properties common to metals but their densities are lower than those of other metals.
2. Alkali metals have one electron in their outer shell which is loosely bound.
3. They have largest atomic radii of the elements in their respective periods.
4. The lower ionization energies result in their metallic properties and high reactivities.
5. An alkali metal can easily lose its valence electron to form positive ion.
6. So they have greater metallic character.
7. The metallic character increases as we move from top to bottom in group due to addition of another shell, it is easy to lose electron.

Question 27.
How do you appreciate the role of electronic configuration of the atoms of elements in periodic classification? (AS6)
(OR)
How does electronic configuration help in the classification of elements in modern periodic table?
Answer:
The quantity is electronic configuration.

1. Modern periodic table is based on electronic configuration. So elements are arranged in ascending order of their atomic numbers.
2. The chemical properties of elements depend on valence electrons. The elements in same group have same number of valence electrons. So the elements belonging to same group have similar properties.
3. So the construction of modern periodic table mainly depends on electronic configuration.
4. Thus electronic configuration plays a major role in the preparation of modern periodic table. So its role is thoroughly appreciated.

Question 28.
Without knowing the electronic configurations of the atoms of elements Mendeleeff still could arrange the elements nearly close to the arrangements in the Modern periodic table. How can you appreciate this? (AS6)
Answer:

• Mendeleeff took consideration about chemical properties while arranging the elements. So the arrangement of elements is close to arrangement of elements in Modern periodic table.
• For this, he violated his periodic law.
• He left some gaps for elements, later those elements are discovered.
• So the efforts of Mendeleeff should be thoroughly appreciated.

Question 29.
Comment on the position of hydrogen in periodic table. (AS7)
Answer:

• Hydrogen is the element which has easier atomic structure than any other element.
• Electron configuration of hydrogen is Is1. It has one proton in its is nucleus and one electron in its is orbital.
• Hydrogen combines with halogens, oxygen and sulphur to form compounds having similar formulae just like alkali metals.
• Similarly, just like halogens, hydrogen also exists as diatomic molecule and combine with metals and non-metals to form covalent compounds.
• As alkali metals hydrogen can lose one electron and accept one electron as halogens.
• So in periodic table, its place may be in IA or VIIA group.
• But based on electronic configuration of hydrogen, it is placed in IA group.

Question 30.
How do the positions of elements in the periodic table help you to predict its chemical properties? Explain with an example. (As7)
Answer:
1) The physical and chemical properties of atoms of the elements depend on their electronic configuration, particularly the outer shell configurations.

2) Elements are placed in the periodic table according to the increasing order of their electronic configuration.

3) The elements in a group possess similar electronic configurations. Therefore all the elements in a group should have similar chemical properties.
Ex : Consider K

• It is the element in 4^th period 1^st group.
• Electron configuration : 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹.
• Differentiating electron enters into s-orbital. Hence it belongs to s-block.
• It is on the left side of the periodic table. Hence it is a metal.
• It is ready to lose one electron to get octet configuration. Hence its reactivity is more.
• It is Alkali metal.
• All alkali metals react with both acids and bases and releases H₂ gas.

Fill In The Blanks

1. Lithium, ……………… and potassium constitute a Dobereiner’s triad.
2. ……………… was the basis of the classifications proposed by Dobereiner, Newlands, and Mendeleeff.
3. Noble gases belong to ……………… group of periodic table.
4. The incomplete period of the modern periodic table is
5. The element at the bottom of a group would be expected to show …………….. metallic character than the element at the top

Answer:

1. Sodium
2. Atomic weight
3. VIIIA or 18 group
4. 7^th
5. higher

Multiple Choice Questions

1. Number of elements present in period – 2 of the long form of periodic table …………
A) 2
B) 8
C) 18
D) 32
Answer:
B) 8

2. Nitrogen (Z = 7) is the element of group V of the periodic table. Which of the following is the atomic number of the next element in the group?
A) 9
B) 14
C) 15
D) 17
Answer:
C) 15

3. Electronic configuration of an atom is 2, 8, 7. To which of the following elements would it be chemically similar?
A) Nitrogen (Z = 7)
B) Fluorine (Z = 9)
C) Phosphorous (Z – 15)
D) Argon (Z = 18)
Answer:
B) Fluorine (Z = 9)

4. Which of the following is the most active metal?
A) lithium
B) sodium
C) potassium
D) rubidium
Answer:
D) rubidium

10th Class Chemistry 9th Lesson Classification of Elements-The Periodic Table InText Questions and Answers

10th Class Chemistry Textbook Page No. 129

Question 1.
Can you establish the same relationship with the set of elements given in the remaining rows?
Answer:
Yes, we can establish the approximately same relationship between other elements given in the table.

Question 2.
Find average atomic weights of the first and third elements in each row and compare it with the atomic weight of the middle element. What do you observe?
Answer:
The atomic weight of middle element is arithmetic mean coverage of first and third elements.

10th Class Chemistry Textbook Page No. 135

Question 3.
What is atomic number?
Answer:
The number of positive charges (protons) in the atom of element is the atomic number of element.

10th Class Chemistry Textbook Page No. 142

Question 4.
How does the valency vary in a period on going from left to right?
Answer:
It does not follow a regular trend when we move from left to right in a period. First, it increases and then decreases and finally ‘O’ for inert gases.

Question 5.
How does the valency vary on going down a group?
Answer:
The valency is constant when we move from top to bottom in a group because the number of valence electrons are same for same group elements.

10th Class Chemistry Textbook Page No. 144

Question 6.
Do the atom of an element and its ion have same size?
Answer:
No, the positive ion has smaller size than neutral atom whereas negative ion has greater size than neutral atom.

Question 7.
Which one between Na and Na⁺ would have more size? Why?
Answer:

• The atomic number of Sodium is 1 and it has 11 protons and 11 electrons with outer electron as 3s¹ whereas Na⁺ ion has 11 protons but only 10 electrons.
• The 3s shell of Na⁺ has no electron in it.
• So the outer shell configuration is 2s²2p⁶.
• As proton number is more than electrons, the nucleus of Na⁺ ion attracts outer shell electrons with strong nuclear force.
• As a result the Na⁺ ion shrinks in size.
• Therefore, the size of Na⁺ ion is less than Na atom.

Question 8.
Which one between Cl and Cl^– would have more size? Why?
Answer:

• The electronic configuration of chlorine (Cl) atom is 1s2 2s² 2p⁶ 3s² 3p⁵ and the electronic configuration of chloride (Cl^–) ion is 1s² 2s² 2p⁶ 3s² 3p⁶.
• Both chlorine and chloride ions have 17 protons each but there are 17 electrons in chlorine atom, whereas 18 electrons in chloride ion.
• Therefore, the nuclear attraction is less in Cl^– ion when compared with chlorine atom.
• Therefore the size of the chlorine (Cl) atom is less size than chloride of Cl^– ion.

Question 9.
Which one in each of the following pairs is larger in size? Why?
a) Na, Al
b) Na, Mg⁺²
c) S^2-, Cl^–
d) Fe²⁺, Fe³⁺
e) C^4-, F^–.
Answer:
a) Na has larger size because Sodium and Aluminium are third period elements in which Na is left to Al. As we move from left to right in a period atomic size decreases.

b) Mg²⁺ has smaller size because Mg²⁺ has 10 electrons and 12 protons whereas Na has 11 electrons and 11 protons. So the distance between nucleus and outermost orbital is less in Mg²⁺ due to greater nuclear attraction.

c) S^2- has, larger size because S^2- has 18 electrons and 16 protons and Cl^– has 18 electrons and 17 protons. So nuclear attraction over outermost orbital is more in Cl^– when compared with S^2-. So S^2- has larger size.

d) In Fe²⁺ it has 26 protons and 24 electrons whereas for Fe³⁺ it has 26 protons and 23 electrons. So nuclear attraction over outermost orbital is more in Fe³⁺. So Fe³⁺ has smaller size (or) Fe²⁺ has larger size.

e) C^4- has 6 protons and 10 electrons whereas F^– has 9 protons and 10 electrons. So nuclear attraction is less in C^4-. So size of C^4- is more than F^–.

10th Class Chemistry Textbook Page No. 129

Question 10.
What relation about elements did Dobereiner want to establish?
Answer:
Dobereiner wanted to give a relationship between the properties of elements and their atomic weights.

Question 11.
The densities of calcium (Ca) and barium (Ba) are 1.55 and 3.51 gem-3 respectively. Based on Dobereiner’s law of triads can you give the approximate density of strontium (Sr)?
Answer:
Molecular weight is directly proportional to density.

So density of strontium is mean of calcium and barium according to Dobereiner.
∴ Density of strontium = \(\frac{1.55+3.51}{2}\) = 2.53.

10th Class Chemistry Textbook Page No. 130

Question 12.
Do you know why Newlands proposed the law of octaves? Explain your answer in terms of the modern structure of the atom.
Answer:

• John Newlands found that when elements were arranged in the ascending order of their atomic weights, they appeared to fall into seven groups.
• Each group contained elements with similar properties.
• If we start with hydrogen and move down, the next eighth element is fluorine, and then next eighth element is chlorine and the properties of these elements are similar.
• Similarly, if we start from Lithium their eighth element is Sodium and next eighth element is potassium. These show similar properties.

Question 13.
Do you think that Newlands’ law of octaves is correct? Justify.
Answer:
No, there are some limitations of Newlands’ model:

• There are instances of two elements fitted into the same slot. Eg : Cobalt and Nickel.
• Certain elements, totally dissimilar in their properties, were fitted into the same group.
• Law of octaves holds good only for the elements up to Calcium.
• Newlands’ periodic table was restricted to only 56 elements and did not leave any room for new elements.
• Newlands had taken consideration about active pattern sometimes without caring the similarities.

10th Class Chemistry Textbook Page No. 134

Question 14.
Why did Mendeleeff have to leave certain blank spaces in his periodic table? What is your explanation for this?
Answer:
1) Mendeleeff predicted that some elements which have similar properties with the elements in a group are missing at that time.
2) So he kept some blanks in the periodic table by writing ’eka’ to the name of the element immediately above the empty space.
3) Later these elements are discovered and they are fitted into those empty spaces.

Question 15.
What is your understanding about Ea₂O₃, EsO₂?
Answer:

• Mendeleeff predicted that after aluminium there was another element namely eka- aluminium (Ea) and after silicon, there was another element namely eka-silicon (Es).
• He also gave the formulae of those oxides as Ea203 and Es02.
• Later those elements are discovered namely gallium and germanium and Ea₂O₃ and EsO₂ as Ga₂O₃ and GeO₂.

10th Class Chemistry Textbook Page No. 135

Question 16.
All alkali metals are solids but hydrogen is a gas with diatomic molecules. Do you justify the inclusion of hydrogen in first group with alkali metals?
Answer:
No, hydrogen shows the properties of both alkali metals and halogens. Still the position of hydrogen has some questions. So it was kept just above alkali metals in first group.

10th Class Chemistry Textbook Page No. 141

Question 17.
Why are lanthanoids and actinoids placed separately at the bottom of the periodic table?
Answer:
The properties of these elements do not coincide with other elements because the valence electron enters 4f and 5f orbitals respectively. So they are placed separately at the bottom of the periodic table.

Question 18.
If lanthanoids and actinoids are inserted within the table, imagine how the table would be?
Answer:
It looks very big in size, and it is difficult to identify, as these elements have similar properties.

10th Class Chemistry Textbook Page No. 145

Question 19.
Second ionization energy of an element is higher than its first ionization energy. Why?
Answer:

• The energy required to remove an electron from unipositive ion is called second ionisation energy.
• It is difficult to remove an electron from unipositive ion when compared with neutral atom due to an increase in nuclear attraction.
• So always second ionisation energy is higher than first ionisation energy.

10th Class Chemistry Textbook Page No. 146

Question 20.
The calculated electron gain enthalpy values for alkaline earth metals and noble gases are positive. How can you explain this?
Answer:

• Generally alkaline earth metals having one, two or three valence electrons prefer to lose electrons in order to get inert gas configuration. So it is difficult to add electron to alkaline earth metals. So they have positive electron gain enthalpy values.
• Noble gases are stable. So they do not prefer to take electrons. So they have positive electron gain enthalpy.

Question 21.
The second period element, for example, ‘F’ has less electron gain enthalpy than the third period element of the same group for example ‘Cl’. Why?
Answer:

• Electron gain enthalpy values decrease in a group as we go down and increase from left to right along a period.
• But the size of Fluorine is small compared chlorine.
• So it is difficult to add electron to fluorine.
• So fluorine has less electron gain enthalpy.

10th Class Chemistry 9th Lesson Classification of Elements- The Periodic Table Activities

Activity – 1

Question 1.
Observe the following table. Establish the relationship of other elements given in the table.

Answer:

Activity – 2

Question 2.
Some main group elements of s-block and p-block have family names as given in the following table.
Observe the long form of a periodic table and complete the table with proper information.

Answer:

Activity – 3

Question 3.
Collect valencies of first 20 elements.
Answer:

AP State Board Syllabus AP SSC 10th Class Biology Important Questions Chapter 2 Respiration.

AP State Syllabus SSC 10th Class Biology Important Questions 2nd Lesson Respiration

10th Class Biology 2nd Lesson Respiration 1 Mark Important Questions and Answers

Question 1.
What are the end products of Aerobic and Anaerobic Respirations?
Answer:
End products of aerobic respiration: Carbon dioxide, Water, Energy
End products of anaerobic respiration: Ethanol / Lactic acid, Carbon dioxide, Energy

Question 2.
In which organisms, blood does not supply the Oxygen?
Answer:
Arthropoda organisms (or) Insects (OR) Tracheal respiratory Organisms.

Question 3.
Hari said that stem also respires along with leaves. How do you support him?
Answer:
Lenticels on stem also help in gaseous exchange in some woody plants along with stomata.

Question 4.
Arrange the apparatus as above and heat the glucose. What will happen to lime water when glucose burns?
Answer:
Lime water turns milky due to carbon dioxide (CO₂).

Question 5.
What is the role of mitochondria in anaerobic respiration?
Answer:
The release of energy from glucose in the presence of oxygen occurs in mitochondria. In anaerobic respiration, as oxygen is absent, mitochondria have no role in respiration.

Question 6.
Fermented idli, dosa produce smell. Name the microorganism responsible for producing such smell.
Answer:
Yeast is responsible for producing such smell in fermented idli, dosa.

Question 7.
In what compound, the energy released during the breakdown of glucose is stored?
Answer:
“ATP” (Adenosine Triphosphate).

Question 8.
Label a and b in the given diagram.

Answer:
(a) Matrix, (b) Cristae.

Question 9.
Name chemical substance produced in human muscles during Anaerobic respiration.
Answer:
Lactic acid is produced in human muscles during Anaerobic respiration.

Question 10.
Why is Diazene Green solution added to the Glucose solution in anaerobic respiration experiment?
Answer:
Diazene Green solution is added to the Glucose solution in anaerobic respiration experiment to check the presence of oxygen in glucose solution.

Question 11.
Name the food material on which trypsin acts and name the end products.
Answer:
i) protein ii) end products – peptones.

Question 12.
“Respiration is the energy releasing process.” Write your opinion on this statement.
Answer:
The given statement is absolutely correct. We respire to use the oxygen to oxidise our food and release energy. This is similar like burning but a slower process. With the help of respiratory enzymes, energy released can be stored in the form of ATP for later use.

Question 13.
Identify the figure.

Answer:
Aerial roots in Mangrove plants.

Question 14.
Can we say that combustion and respiration are almost same actions? What evidences do you have for this?
Answer:

1. In both these processes sugar is converted to carbon dioxide and water.
2. Both these processes require oxygen.
3. Both combustion and respiration releases energy.

Question 15.
What is the role of epiglottis in respiration and swallowing food?
Answer:
The epiglottis is a flexible flap at the superior end of the pharynx in the throat. Epiglot¬tis acts as a lid over glottis and prevents food from entering into larynx. Air from pharynx enters the larynx while food enters into oesophagus.

Question 16.
What is the function of haemoglobin?
Answer:
During respiration haemoglobin carries oxygen to the cells and CO, from cells to lungs.

Question 17.
What is respiration?
Answer:
Respiration is the process by which food is broken down to release energy.

Question 18.
What does the word respiration mean in Latin?
Answer:
In Latin the word respiration means “to breathe”.

Question 19.
Who did comprehensive work on properties of gases, their exchange and respiration?
Answer:
Lavoisier and Priestly.

Question 20.
What was the gas liberated on heating powdered charcoal in a bell jar?
Answer:
It was fixed air. In those days carbon dioxide was known as fixed air.

Question 21.
What is oxygen debt?
Answer:
It is the inadequate supply of oxygen when we undertake strenuous exercise.

Question 22.
What is vitiated air?
Answer:
It is the term used then to show air from which the component needed for burning had been removed.

Question 23.
What is the total lung capacity of human being?
Answer:
The total lung capacity of human being is nearly 5800 ml.

Question 24.
Who was the renowned chemist who wrote a textbook of Human Physiology?
Answer:
John Daper was the renowned chemist who wrote a textbook of Human Physiology.

Question 25.
What happens when air passes through nasal cavities?
Answer:

1. Air is filtered in nasal cavity by mucus lining and the hairs growing from its sides, remove some of the tiny particles of dirt in the air.
2. The temperature of the air is brought close to that of the body.

Question 26.
What is the function of epiglottis?
Answer:
Epiglottis controls the movement of air and food towards their respective passages.

Question 27.
What is breathing?
Answer:

1. Breathing is the process of inhaling and exhaling.
2. The mechanism by which organisms obtain oxygen from the environment and release CO₂ is called breathing.

Question 28.
What are pleura?
Answer:
Pleura are the two membranes that protect lungs from injury.

Question 29.
What is the concentration of oxygen at a height of 13 km from the sea level?
Answer:
At a height of 13 km above sea level the concentration of oxygen is much lower about one-fifth as great as at sea level.

Question 30.
What is cellular respiration?
Answer:
Oxidation of glucose or fatty acids takes place in the cells releasing energy. Hence this process is known as cellular respiration.

Question 31.
Where does aerobic respiration occur in eukaryotic cells?
Answer:
Aerobic respiration occur in cytoplasm and mitochondria of eukaryotic cells.

Question 32.
What is Glycolysis?
Answer:
It is the first stage of respiration. In this breakdown of glucose molecule into two molecules of 3 carbon compound called pyruvic acid or pyruvate releasing energy.

Question 33.
What is the fate of pyruvate in the absence of oxygen in animals?
Answer:
In the absence of oxygen pyruvate will be converted to lactic acid and release small amount of energy in animals.

Question 34.
In which type of respiration pyruvate is converted into carbon dioxide and water?
Answer:
In aerobic respiration pyruvate is converted into carbon dioxide and water.

Question 35.
What is the main reason for feeling pain in muscles after strenuous exercise?
Answer:
Due to the anaerobic respiration in muscles large amounts of lactic acid is accumulated and this results in muscular pains.

Question 36.
What is fermentation?
Answer:
In the absence of oxygen, yeast cells convert pyruvic acid to ethanol. This process is called fermentation.

Question 37.
What is the method used to separate ethanol from the yeast glucose mixture in anaerobic respiration?
Answer:
The method used to separate ethanol from the yeast glucose mixture in anaerobic respiration is fractional distillation.

Question 38.
In which organisms does exchange of gases take place through diffusion?
Answer:
In Amoeba, hydra and planarians exchange of gases takes place through diffusion.

Question 39.
In tracheal respiratory system which carry air directly to the cells in the tissues?
Answer:
Trachioles, the fine branches of trachea carry air directly to the cells in the tissues.

Question 40.
What are the respiratory organs in fishes?
Answer:
Gills or bronchiae are the respiratory organs in fishes.

Question 41.
What is cutaneous respiration?
Answer:
If the respiration occurs through skin, it is known as cutaneous respiration, e.g : Leech, Earthworm and Frog.

Question 42.
What are the other areas on the plant body through which gaseous exchange take place?
Answer:
The areas on the plant body through which geseous exchange take place are the surface of roots, lenticels on the stem.

Question 43.
What is the full form of ATP? How is it formed?
Answer:
I) ATP stands for Adenosine triphosphate.
2) ATP is used to supply energy in the cells for the carrying all the metabolic processes.

Question 44.
What are the factors that control respiration?
Answer:
Oxygen and temperature are the two important factors that control the process of respiration.

Question 45.
What are the substances that are used for the production of energy in all living organisms?
Answer:
Glucose and fatty acids are used for the production of energy in all living organisms.

Question 46.
How many types of respiration are present? What are they?
Answer:
There are two types of respiration. They are :

1. Aerobic respiration and
2. Anaerobic respiration.

Question 47.
Where is energy stored in ATP?
Answer:
Energy is stored in the terminal phosphate bond in ATP which is having three phosphates attached to a molecule of Adenosine.

Question 48.
What are the power houses of the cell?
Answer:
Mitochondria are the power houses of the cell.

Question 49.
What is the main difference between respiration and combustion?
Answer:
In respiration several intermediates are produced and in combustion, there are no such intermediates are produced.

Question 50.
What is the equation that represents respiration?
Answer:
The equation that represents respiration is

Question 51.

.
What are the sites of cellular respiration?
Answer:
Mitochondria are the sites of cellular respiration.

Question 52.
What are cristae in mitochondria?
Answer:
The inner membrane of mitochondria is thrown into several folds called cristae.

Question 53.
What is the net gain of ATP molecules in Glycolysis?
Answer:

1. Four ATP molecules are produced when one molecule of glucose is converted to two molecules of pyruvate but two are consumed.
2. The remaining two ATP molecules are net gain in glycolysis.

Question 54.
How many ATP molecules are produced when one glucose molecule is completely oxidised?
Answer:
A net gain of 38 ATP molecules are formed from the total oxidation of one glucose molecule.

Question 55.
What are the three stages present in complete oxidation of glucose molecule?
Answer:
The three stages present in complete oxidation of glucose molecule are

1. Glycolysis
2. Kreb’s cycle and
3. Electron transport.

Question 56.
Why does oxidation of fatty acids give more energy?
Answer:
Oxidation of fatty acids give more energy due to the presence of more carbon atoms in them.

Question 57.
What are aquatic and terrestrial animals?
Answer:
Animals that live in water are called aquatic animals and that live on land are known as terrestrial animals.

Question 58.
Why is the rate of breathing in aquatic organisms much faster than terrestrial organisms?
Answer:

1. The amount of oxygen dissolved in water is low when compared to the amount of oxygen present in air.
2. Therefore the rate of breathing in aquatic animals is much faster than in terrestrial animals.

Question 59.
Which part of the roots is involved in the exchange of respiratory gases?
Answer:
The part of roots that are involved in the exchange of respiratory gases are root hairs.

Question 60.
What is the average breathing rate in an adult mem at rest?
Answer:
The average breathing rate in an adult man at rest is about 15 to 18 times per minute.

Question 61.
Why is the trachea prevented from collapsing?
Answer:
The walls of the trachea are supported by several ‘C’ shaped cartillagenous rings. They prevent the trachea from collapsing and closing.

Question 62.
Why deos the percentage of carbon dioxide increase in exhaled air?
Answer:
During oxidation of glucose carbon dioxide is produced as waste product. Hence the concentration of carbon dioxide increases in exhaled air.

Question 63.
How does breathing take place in mangrove plants?
Answer:
In mangrove plants breathing takes place through specialised structures called breath¬ing roots or pneumatophores.

Question 64.
How does respiration take place in plants where roots are present in wet places?
Answer:
The plants which have their roots in very wet places have much larger air spaces, connect the stems with the roots, making diffusion from upper parts.

Question 65.
Which form a continuous network all over the plant?
Answer:
The stomatal openings lead to a series of spaces between the cells inside the plant which form a continuous network all over the plant.

Question 66.
What are the reasons for the animals to develop different types of respiratory organs?
Answer:
Body size, availability of water, habitat in which they live and the type of circulatory system are some of the reasons for the animals to develop different types of respiratory organs.

Question 67.
Why do fishes die when taken out of water?
Answer:
Fishes do not have lungs to utilise oxygen for breathing. They have gills which can utilize only dissolved oxygen from water.

Question 68.
What would be the consequences of deficiency of haemoglobin in our bodies?
Answer:
Deficiency of haemoglobin in blood can affect the oxygen supplying capacity of blood to body cells. It can also lead to a disease called Anaemia.

Question 69.
What are the stages of respiration in man?
Answer:
Respiration in man occurs in two stages 1) Inhalation (or) Inspiration 2) Exhalation (or) Expiration.

Question 70.
Which part plays major role in respiration of man?
Answer:
Diaphragm plays a major role in respiration in man.

Question 71.
Which part plays major role in respiration of woman?
Answer:
In woman ribs play a major role in respiration.

Question 72.
How are lungs protected?
Answer:
Lungs are protected by two membranes called pleura. A fluid between these membranes protects the lungs from injury.

Question 73.
What is the composition of exhaled air?
Answer:
Exhaled air contains 16% of oxygen, 4% of carbon dioxide and 79% of nitrogen.

Question 74.
Why are red blood cells red in colour?
Answer:
Red blood cells are red in colour due to the presence of haemoglobin in their cytoplasm.

Question 75.
How is haemoglobin made up of?
Answer:
Haemoglobin is made up of a protein called globin, Iron (Hearn) and organic molecule called porphyrin.

10th Class Biology 2nd Lesson Respiration 2 Marks Important Questions and Answers

Question 1.
(a) Which gas turns lime water milky in this experiment?
Answer:
Carbondioxide (or) CO₂

(b) Which gas do you think might be present in less quantities in the air we breath out as compared to air around us?
Answer:
Oxygen (or) O₂

Question 2.
Balu said that, “Plants perform Photosynthesis during day time. They respire during night time”.
Do you agree with Bain? Why? Why not?
Answer:

1. I do not agree with Balu’s statement.
2. Photosynthesis depends on light for energy but respiration does not depend on light.
3. Hence, photosynthesis takes place during day time only whereas respiration takes place both day and night.

Question 3.
The sportsman who participated in 100 mtr race get more muscle pains. But the sportsman who participates in 5 km’s race get less muscle pains. What is the reason?
Answer:

1. Accumulation of lactic acid results in muscular pain.
2. During 100 m race a well trained athlete can hold his breath and afterwards he pants.
3. In this case, the muscles are using energy released during the anaerobic break down of glucose, lactic acid is produced.
4. The presence of lactic acid in the blood is the main cause of muscle fatigue. Whether it is 100 mtr race or 5 km race.
5. If the body is rested long enough the tiredness goes.

Question 4.
What happens if there is no epiglottis in human beings?
Answer:

1. Food may enters into the larynx.
2. Food may enters into the lungs leading to the death.
3. May not speak properly.
4. Entry of food and air may not be regulated properly.

Question 5.
Write two chemicals and two materials required to conduct the experiment “Heat and Carbon dioxide are evolved during anaerobic respiration”.
Materials required: Thermosflask, splitted corks, thermometer, wash bottle, glass tubes.
Chemicals required: Liquid paraffin, glucose solution, bicarbonate solution, Janus green B and Yeast cells.

Question 6.
Observe the below diagram.
A) To which biosystem is this picture related?
Answer:
Respiratory system.

B) Write the names of the parts of A, B.
Answer:
A – alveolus; B – blood capillary network

C) To which system are they linked with?
Answer:
Respiratory system; circulatory system.

D) Which process is happening here? What happens as a result of it?
Answer:
Gaseous exchange between alveolus of lungs and blood capillaries. Due to this the CO₂, present in blood capillaries enter alveolus and oxygen present in alveolus en¬ter blood capillaries.

Question 7.
A person reached a specific distance once on foot and once by running. In which situation his legs pain? Why?
Answer:

1. When a person runs to reach a specific distance gets pain in his legs.
2. This is due to the production of lactic acid in the muscles.
3. Due to the Anaerobic respiration glucose in muscles converts into lactic Acid.
4. Accumulation of lactic acid causes pain in leg muscles.

Question 8.
What is the advantage of the wet and warm passage of air from the nostrils to capillaries?
Answer:
When the air passes in nasal cavity and in the pharynx some changes take place.

1. The mucus layer and hair in the nasal cavity removes the dust particles in the air.
2. The temperature of the air brought to the body temperature.
3. Moistening the air.

Question 9.
In the experiment of anaerobic respiration with yeast
i) Why was liquid paraffin poured on glucose?
ii) What did you understood about anaerobic respiration?
Answer:
i) The supply of oxygen from the air can be stopped by pouring liquid paraffin on glucose.
ii) Anaerobic respiration takes place in the absence of oxygen. In this glucose molecule is incompletely oxidised. The end products of anaerobic respiration are ethyl alcohol or lactic acid and CO₂.
During anaerobic respiration small amount of energy is liberated (2ATP). Anaero¬bic respiration occurs in many anaerobic bacteria and human muscles cells. The anaero¬bic respiration can be represented as:
C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂+ 56 K.Cal.

Question 10.
See the below table. Write what you know from it.

Answer:

1. The inhaled air consists of 21% of oxygen whereas the exhaled air contains 16% of oxygen only. This is due to utlilisation of oxygen during cellular respiration in the body. Hence the difference occurs.
2. Inhaled air contains 0.04% of carbondioxide whereas exhale air contains 4% of carbondioxide.
   The concentration of CO₂ is increased a lot due to the release of CO₂ during cellular respiration in the body.
3. Both inhale and exhale air contains 79% of nitrogen because nitrogen has no role to play in cellular respiration.

Question 11.
What is the pathway of air from nostril to alveolus?
Answer:
Draw a flow chart of Respiratory passage of Humans.

Question 12.
What happens when a baker prepares a dough by mixing yeast in it?
Answer:

1. The yeast is commonly used for fermenting bread is saccharomyces cerevisiae.
2. Baker’s yeast has the advantage of producing uniform, quick, and reliable results because it is obtained from pure culture.
3. Water is mixed with flour, salt and the fermenting agent.
4. The mixed dough is then allowed to rise one or more times.
5. Then loaves are formed and the bread is baked in air oven.

Question 13.
How does respiration in amoeba and hydra occur through diffusion? (OR)
What are the similarities in respiration of amoeba and hydra?
Answer:

1. Amoeba and hydra are aquatic organisms.
2. Respiration in them occurs through diffusion.
3. As oxygen is used by these organisms in respiration, its concentration is reduced in cytoplasm. Hence oxygen diffuses into cytoplasm from surrounding water.
4. During respiration CO₂ is continuously produced, its concentration increases in the cytoplasm, hence it diffuses into surrounding water.

Question 14.
Write a short note on ATP. (OR) Expand ATP.
Answer:

1. From the break down of glucose the energy is released and stored up in a special compound known as ATP (Adenosine Triphosphate).
2. It is a small parcel of chemical energy. The energy currency of these cells is ATP an energy rich compound that is capable of supplying energy whenever needed within the cell.
3. Each ATP molecule gives 7200 calories of energy. This energy is stored in the form of phosphate bonds.
4. If the bond is broken, the stored energy is released.

Question 15.
How do Dolphin and Crocodile respire?
Answer:

1. The aquatic animals like dolphin and crocodile respire with the help of lungs.
2. They come out of the water for air.
3. These two animals were lived on land initially.
4. Later they lived in water and developed several adaptations to live in water.

Question 16.
Why are Mitochondria called “Power houses of cell”? (QR)
What is the energy producing organ in a cell? How does it produce energy?
Answer:

1. Cellular respiration in prokaryotic cells like that of bacteria occurs within the cytoplasm.
2. In eukaryotic cells cytoplasm and mitochondria are the sites of reaction.
3. The produced energy is stored in mitochandria in the form of ATP.
4. Hence, mitochondria are called “Power houses of cell”.

Question 17.
Write the rate of respiration in different age groups of human beings.
Answer:

1. Newborn child: 32 times per minute
2. Children of 5 years: 26 times per minute
3. Man of 25 years: 15 times per minute
4. Man of 50 years: 18 times per minute

10th Class Biology 2nd Lesson Respiration 4 Marks Important Questions and Answers

Question 1.
Write about respiration in mangroves that grow in marshy lands.
Answer:

1. Mangroves grown near the marshy places respire through aerial roots or respiratory roots.
2. The root hairs exchange the gases from their surface.
3. They obtain oxygen from the airspaces present between the soil particles.
4. The plants grown in marshy places are adapted to develop aerial roots above the soil surface which helps in gaseous exchange.

Question 2.
a) What is the aim of this experiment?
Answer:
Heat is liberated during respiration.

b) What change do you observe in thermometer readings?
Answer:
Reading increases in the thermometer.

c) In your opinion, where did this heat come from?
Answer:
The heat comes from the germinating seeds which respire and releasing heat.

d) What precaution should we take, while doing this experiment?
Answer:
The bulb of the thermometer should be dip in the germinating seeds (or) sprouts.

Question 3.
You have conducted this experiment in your classroom. Now answer the following questions.
a) What do you prove by conducting this experiment?
Answer:
To test the production of heat and carbon dioxide during anaerobic respiration.

b) Why do you heat glucose solution?
Answer:
To remove the dissolved oxygen in the glucose solution.

c) How do you confirm that glucose solution is free from oxygen after heating it?
Answer:
By adding diazine green (Janus green B) solution to glucose solution, it turns to pink.

d) What are the changes you notice in the lime water?
Answer:
Lime water turns milky white.

Question 4.

i) What change did you observe in the thermometer in the given experiment?
Answer:
Raise in the temperature

ii) Where does the heat come from?
Answer:
From the germinating seeds during respiration

iii) What result you will get, if you perform this experiment with dry seeds?
Answer:
No change of temperature in thermometre.

iv) What are the apparatus used in this experiment?
Answer:
Glass jar, germinating seeds, cork, thermometer.

Question 5.
Observe the set of apparatus and answer the following questions.
i) Which process do we know with the help of this experiment?
Answer:
Combustion.

ii) How does this process differ with respiration?
Answer:
Respiration occurs in the presence of water.
Combustion occurs in the absence of water.

iii) What are the similarities between this process and respiration?
Answer:
In both processes energy is released.

iv) Which gas turns lime – water milky?
Answer:
Carbon-di-oxide (CO₂)

Question 6.
Look at the following experiment. Answer the questions.

a) What is the aim of the experiment?
Answer:
The aim of the experiment is CO₂ is released during anaerobic respiration.

b) Which agent is used to find the presence of oxygen?
What changes do you observe when oxygen is present in Glucose solution?
Answer:
To find the presence of oxygen diazine green (Janus Green B) solution is used. The blue diazine green solution turns pink when oxygen is present in the glucose solution.

c) Why is liquid paraffin poured on glucose solution?
Answer:
By pouring liquid paraffin on glucose solution, the supply of oxygen from the air can be cut off.

d) Which gas is released during the experiment? How can you prove it?
Answer:
Carbon dioxide is released.
The released CO₂ passes into lime water it turns milky.

Question 7.
Observe the following diagram and answer the following questions.

1. What do we call the membranes that cover the lungs?
2. What is the functional unit of lungs ?
3. Which part produces the sound ?
4. What does ‘X’ denote ?

Answer:

1. Pleura
2. Alveoli
3. Larynx
4. Trachea

Question 8.
Observe the diagram and answer the following questions.

a) What does the given diagram indicate?
b) What is the part ‘X’ in the diagram?
c) What is the function of the given picture?
d) To which system the given picture belongs to?
Answer:
a) The given diagram indicates mitochondria.
b) Matrix
c) Performing cellular respiration and releasing energy in the form of ATP.
d) Respiratory system.

Question 9.
Observe the experimental setup and answer the given questions.
A) What is the aim of this experiment?
B) What are the apparatus required for this experiment?
C) What changes do you observe in thermometer during this WKm experiment?
D) What will happen, if dry seeds are taken instead of germinating seeds in this experiment?
Answer:
A) Heat is liberated during respiration.
B) Glass jar, Germinating seeds, Cork and Thermometer.
C) We can notice the raise in temperature after observing the thermometer readings.
D) There will be no change of temperature in the thermometer. We can’t prove the aim of the experiment.

Question 10.
Observe the below diagram and answer the following questions:
i) What does the above setting (diagram) indicate?
Answer:
The above setting (diagram) indicates to prove that carbon dioxide and heat are liberated during anaerobic respiration by yeast cells.

ii) Why is boiled and cooled glucose covered with paraffin?
Answer:
To prevent supply of air, boiled and cooled glucose is covered with paraffin.

iii) What is the use of adding diazine green to glucose solution? What change you notice in glucose solution?
Answer:
Diazine green is added to glucose solution to know whether oxygen is present or not in glucose solution. When the availability of oxygen is less the diazine green changes to pink colour.

iv) Why is lime water used in this experiment?
Answer:
To know whether carbon dioxide is released or not in this experiment lime water is used. Carbon dioxide changes lime water to milky white.

v) Why is bulb of thermometer dipped in the glucose water?
Answer:
To know the rise in temperature of glucose solution when heated, the bulb of thermometer is dipped in the glucose water.

Question 11.
Explain with the help of a flow chart, the path way of air in humans.
Answer:

Question 12.
Study the graph and answer the following questions :
Graph showing effects of vigorous excercise on the concentration of lactic acid in blood.
i) What was the concentration of lactic acid in blood to start with?
ii) What was the greatest concentration of lactic acid reached during the experiment?
iii) What is the concentration of lactic acid after 25 minutes of exercise?
iv) What is the relationship between lactic acid and muscle pain?
Answer:
i) 20 mg/cm³
ii) 20 minutes (Or) at “B” point,
iii) 101 mg/cm³
iv) If concentration of lactic acid increases, muscle pains also increases.

Question 13.
Observe the following :

Write the answers to the following questions:
i) How many Pyruvic acid molecules form from one Glucose?
Answer:
2 Pyruvic acid molecules.

ii) What conditions influence Pyruvic acid to participate in Aerobic and Anaerobic respiration?
Answer:
Presence of oxygen

iii) In which we get more energy in both Aerobic and Anaerobic respirations?
Answer:
Aerobic respiration

iv) The chemical that is formed in human muscles during Anaerobic respiration.
Answer:
Lactic acid

Question 14.
Why does the exchange of gases happen only in alveoli, though arteries are present in pharynx, trachea and bronchus?
Answer:

1. Alveoli are tiny air sacs in the lungs surrounded by capillaries
2. They are numerous and only single cell thickness
3. They increase the efficiency of gas exchange.
4. Due to the difference in a gradient of O₂ oxygen diffuse from alveoli to blood capillaries.

Question 15.
What are the events or steps in respiration?
Answer:
The following are the events or steps in respiration.

1. Breathing: Air moves into lungs and out of lungs.
2. Gaseous exchange in lungs: Exchange of gases between alveoli and blood.
3. Gas transport by blood: Transport of oxygen from blood capillaries of alveoli to body cells and return of carbon dioxide.
4. Gaseous exchange in cells: Exchanging oxygen from blood into the cells and carbon dioxide from cells into the blood.
5. Cellular respiration: Using oxygen in cell processes to produce carbon dioxide and water, releasing energy to be used for life processes.

Question 16.
What will happen if the respiratory tract is not moist? (OR)
Why respiratory tract should be moist?
Answer:

1. If the respiratory tract is not moist the dirt particles in the inhaled air will not be removed from air in the nasal cavities and reaches lungs and creates problems to lungs.
2. The temperature of the inhaled air is brought close to that of the body for the smooth passage in the respiratory tract. If it is dry, it is not possible.
3. If the surface dries out, gas exchange will happen at a very reduced rate since fast moving gaseous oxygen molecules do not efficiently cross the alveoli membrane.
4. The reduced gas exchange is most likely not enough to support blood oxygenation for vital functions.
5. Hence respiratory tract should be moist for smooth exchange of gases.

Question 17.
Explain the process of transportation of gases through the blood.
Answer:

1. The relative amount of gases and their combining capacity with haemoglobin and other substances in blood determine their transport via blood in the body.
2. When oxygen present in the air is within normal limits (around 21%) then almost all of it is carried in the blood by binding to haemoglobin, a protein present in the red blood cells.
3. As oxygen is diffused in the blood, it rapidly combines with the haemoglobin to form oxyhaemoglobin.
4. Not only can haemoglobin combine with oxygen, but it can easily broken into haemoglobin and oxygen.
5. Carbon dioxide is usually transported as bicarbonate, while some amount of it combines with haemoglobin and rest is dissolved in blood plasma.
   

Question 18.
Why is human life impossible at higher altitudes without a supplementary supply of oxygen? (OR)
The concentration of oxygen in air decreases as we go up from sea level. Explain briefly.
Answer:

1. If haemoglobin is exposed to air at sea level, every molecule in air combines with oxygen to form oxyhaemoglobin.
2. At a height of 13 km above sea level, the concentration of oxygen is much lower about l/5th of a sea level.
3. Under these conditions about half as many molecules of oxygen combine with haemoglobin to form oxyhaemoglobin.
4. Blood cannot carry enough oxygen to the tissues.
5. Hence human life is impossible at such a high altitude without a supplementary supply of oxygen.
6. Provision for such a supply is built into modern aircraft which have pressurized cabins that maintain an enriched air supply.

Question 19.
What are the different ways in which glucose is oxidised to provide energy in various organisms? Give one example of each.
How does oxidation of glucose occur in various organisms?
Answer:

1. Glucose is the most commonly used sugar for deriving energy in plants, animals and in microorganisms.
2. In all these organisms glucose is oxidized in two stages.
3. The first stage is known as Glycolysis. It occurs in cytoplasm.
4. During glycolysis glucose is converted to two molecules of pyruvic acid.
5. In the second stage if oxygen is available pyruvic acid is converted to C02 and water, large amount of energy is released. This is known as aerobic respiration. It occurs in most of the plant and animal cells.
6. If oxygen is inadequate or not available, pyruvic acid is converted into ethanol and carbon dioxide. This is anaerobic respiration taking place in yeast cells that is called fermentation.
7. If oxygen is not available in muscle cells, the pyruvic acid is converted into lactic acid.
   

Question 20.
Write the adaptations seen in plants living in water logged conditions.
(OR)
What are the adaptations seen in magrove plants?
Answer:

1. Most plants can aerate their roots by taking in the oxygen through lenticels or through the surface of their root hairs.
2. But plants which have their roots in very wet places, are unable to do this.
3. They are adapted to these water logged conditions by having much larger air spaces which connect the stems with the roots, making diffusion from the upper parts much more efficiently.
4. The problem of air transportion is more difficult for trees and may not survive with their roots permanently in water.
5. To overcome this problem the mangrove tree of the tropics which raise up aerial roots above the surface and takes in oxygen.

Question 21.
Describe the mechanism of branchial or gill respiration in fishes.
(OR)
Briefly explain the process of exchange of gases in fishes during respiration.
Answer:

1. Some aquatic animals like fishes have developed special organs for respiration which are known as gills or branchiae.
2. Blood is supplied to gills through capillaries which have thin walls where gases are exchanged. Gills are present in the gill pouches or branchial pouches.
   
3. Gills are provided with leaf-like folds called gill lamellae.
4. Fish keeps its mouth open and lowers the floor of the oral cavity. As a result water from outside will be drawn into the oral cavity.
5. Now the mouth is closed and the floor of the oral cavity is raised.
6. Water is pushed into the pharynx and is forced to gill pouches through internal branchia apertures.
7. When water passes through gill lamellae exchange of gases takes place, that is oxygen diffuses from water to blood and CO₂ from blood into water.
8. Then water flows through external branchia aperture.

Question 22.
Explain briefly about Pranayama- the art of breathing. (OR)
How can the capacity of lungs be improved by yoga?
Answer:

1. To improve breathing capacity the saint Patanjali developed Yogabyasa.
2. The art of breathing in Yogabyasa is called Pranayama. Prana means gas, ayama means journey.
3. In Pranayama practice air is allowed to enter three lobes of lungs in order to in¬crease the amount of oxygen to diffuse into blood.
4. More amount of oxygen available to brain and tissues the body will be more active.
5. It is very important to practise Pranayama regularly to make our life healthy and active.
6. All people irrespective of age and sex should practise Pranayama under the guidance of well trained Yoga Teacher to improve the working capacity of lungs.

Question 23.
What are the experiments carried out by Lavoisier to understand the property of gases?
Answer:

1. In his early experiments Lavoisier thought that the gas liberated on heating powdered charcoal in a bell jar kept over water in a trough was like fixed air i.e., carbon dioxide.
2. The next series of experiments deals with the combustion of phosphorous in a bell jar. From this he showed that whatever it was in the atmospheric air which combined with the phosphorous was not water vapour.
3. This was respirable air, a component of air that also helped in burning.
4. The air that we breathe out precipitated lime water while that after heating metal did not.
5. From this, he concluded that there were two processes involved in respiration.
6. Lavoisier carried out another experiment by which he showed that about one sixth of the volume of ‘vitiated air’ consists of chalky acid gas (fixed air).
7. Either eminently respirable air is changed in the lungs to chalky acid air; or an exchange takes place, the eminently respirable air being absorbed, and an almost equal volume of chalky acid air being given up to the air from the lungs.
8. Lavoisier had to admit that there were strong grounds for believing that eminently respirable air did combine with the blood to produce the red colour.

Question 24.
Explain the evolutionary changes in energy-releasing system.
(OR)
What are the different respiratory systems in animal groups?
Answer:
Exchange of gases is a common life process in all living organisms, but it is not same in all.

1. Diffusion:
   1. Single-celled organisms like amoeba or multicellular organisms like hydra and planarians obtain oxygen and expel carbon dioxide directly from the body by the process of diffusion.
   2. In multicellular animals special organs are evolved.
   3. Body size, availability of water and the type of circulatory system are some of the reasons for the animals to develop different types of respiratory organs.
2. Tracheal respiratory system : In insects tracheal respiratory system is present in which small branches of trachea called trachioles carry air directly to the cells in the tissues.
3. Bronchial respiration : In fishes gills are utilised for the exchanges of gases. Blood is supplied to gills through capillaries which have thin walls for exchange of gases. This is called bronchial respiration.
4. Cutaneous respiration: 0 Respiration through skin is called cutaneous respiration.
   Eg: i) Earth worms and leeches.
   ii) Frog, an amphibian can respire through lungs and skin.
5. Pulmonary respiration : Most of the higher animals respire with the help of lungs. This type of respiration is known as pulmonary respiration. Eg: Mammals.

Question 25.
Describe the structure of mitochondria with the help of a diagram. (OR)
Which cell organelle is called energy currency or power house of cell? What do you know about its construction?
Answer:
Mitochondria is known as energy currency or power house of cell.
Structure of mitochondria:

1. Mitochondria are sac-like structures present in the cytoplasm of the cells.
2. Mitochondria have two compartments-an inner compartment and an outer compartment. The substance in the inner compartment is called matrix.
3. The matrix is surrounded by a membrane called inner membrane of mitochondria.
4. The inner membrane is thrown into several folds called cristae. The cristae extended into the matrix.
5. The space between the folds is continuous with the outer compartment.
6. On the inner membrane, projecting into the matrix are a large number of particles called elementary particles.
7. These particles have a spherical head and a stalk. They are attached to the inner membrane by their stalk and the head portion of the particle is in the matrix.
8. The outer compartment is surrounded by another membrane – the outer membrane. The outer membrane is smooth and has no projections.
9. The inner membrane, the matrix and the elementary particles in the mitochondria have large number of enzymes and other required proteins for the respiration and energy production.

Question 26.
Draw and label mitochondria. Why should we call it cell of power ?
Answer:

Oxidation of glucose molecule occurs in the mitochondria, ot cell. This is known as cellular respiration. The energy produced during cellular respiration stored in the form of ATP molecule. Energy producing cellular respiration occurs in mitochondria hence we call it cell of power or power house of the ceil.

Question 27.
Describe how oxygen enters the blood in lungs with the help of block diagram.
(OR)
How does gaseous exchange occur in lungs?
Answer:

1. Gaseous exchange takes place within the lungs by diffusion from the alveoli to blood capillaries and vice versa. Alveoli in lungs are numerous and only one cell thick.
   
2. Alveoli are surrounded by capillaries that are also one cell thick.
3. Blood, dark red in colour flows from the heart through these capillaries and collects oxygen from the alveoli.
   At the same time, carbon dioxide passes out of the capillaries and into the alveoli.
4. When we breathe out, we get rid of carbon dioxide.
5. The bright red, oxygen rich blood is returned to the heart and pumped out to all parts of the body.

Question 28.
What is the role of diaphragm and ribs in respiration? Are both active in man and woman?
Answer:
Diaphragm:

1. Diaphragm is a muscular dome shaped tissue present at the floor of the chest cavity separating abdomen from respiratory system.
2. Diaphragm expands downwards into the abdomen thus increasing chest cavity. This allows the lungs to expand as we inhale.
3. As the diaphragm contracts upwards thus decreasing the chest cavity, it allows the air to expel from the lungs.
   Ribs:
4. The ribs protect the lungs and expand as we inhale to facilitate space for the lungs to expand. The ribs then contract expelling the air from the lungs.
5. The intercostal muscles present between the ribs help in contraction and relaxation of ribs.
6. In man, diaphragm plays a major role in the respiration, while in woman, the ribs play a major role.

Question 29.
Why are alveoli so small and uncountable in number? (OR)
How do alveoli increase the area for exchange of gases?
Answer:

1. The pouch-like air sacs at the ends of the smallest branchioles are called alveoli.
2. The walls of the alveolus are very thin and they are surrounded by very thin blood capillaries.
3. It is in the alveoli that gaseous exchange takes place.
4. There are millions of alveoli in the lungs. The presence of millions of alveoli in the lungs provides a very large area for the exchange of gases.
5. And the availability of large surface area maximises the exchanges of gases.

Question 30.
Write a brief note on respiration in plants. (OR)
Does respiration occur in plants? Explain briefly about it.
Answer:

1. In most plants exchange of gases takes place through stomata.
2. There are other areas on the plant body like surface of roots, lenticels on stem, etc. the gaseous exchange takes place.
   
3. Some plants have specialized structures like breathing roots of mangrove plants as well as the tissue in orchids.
4. Breathing roots and tissue in orchids help plants to take oxygen to produce energy and release carbon dioxide.
5. Inside the plants openings lead to a series of spaces between the cells which form a continuous network all over the plant.
6. The whole system works by diffusion.
7. As the oxygen is used up by the cells a gradient develops between the cells and the air in the spaces.
8. So oxygen passes in between the air spaces and the air outside stomata and lenticels.
9. In the same way, as more carbon dioxide is given out by the cells, a gradient occurs in the reverse direction and it passes out.

Question 31.
Write a brief note on tracheal respiration in insects.
Answer:

1. In insects blood do not contain haemoglobin, and blood is white in colour. Hence it cannot carry oxygen.
2. For respiration insects adopt a special system called tracheal system.
   
3. This system consists of a series of tubes called trachea.
4. These trachea open out through small apertures called spiracles on either side of the body.
5. All tracheal tubes of each side join and form a longitudinal tracheal trunk.
6. Trachea divide into a number of branches called tracheoles which carry air directly to the tissues.
7. As the air moves in and out of the trachea, oxygen present in the air diffuses into the cells and CO₂ diffuses into the air from the cells.

Question 32.
Write about the mechanism of respiration in human beings. (OR)
How does exchange of gases take place in human beings?
Answer:

1. Respiration in man occurs in two stages. They are inspiration and expiration.
2. During inspiration air from outside enters into the lungs by increasing the chest cavity.
   
3. Increase in the chest cavity is made by pulling the diaphragm down and pushing the ribs forward.
4. As the air pressure in the lungs is reduced, air from outside enters the lungs through external nostrils, nasal cavities, internal nares, pharynx, epiglottis, larynx, trachea, bronchi and branchioles and finally reach the alveoli where exchange of gases takes place.
5. During expiration the diaphragm and ribs come back to original positions.
   
6. This reduces the volume of chest cavity.
7. So the volume of lungs is decreased and air under pressure comes out of the lungs.

Question 33.
Study the graph given below and analyse the reasons for accumulation of lactic acid in blood after strenuous exercise.

Answer:

1. This graph shows the relation between time accumulation of lactic acid in the muscles.
2. At the beginning, the amount of lactic acid in the blood is very less.
3. Gradually it is increased by vigorous exercise.
4. Within 15 minutes it goes to maximum level which causes muscle pain.
5. Then the lactic acid is removed from muscles in an hour.
6. Muscles produce energy by anaerobic respiration.
   C₆H₁₂O₆ → lactic acid + CO₂ + energy
7. In the vigorous exercise, muscle work rapidly and produce more lactic acid.
8. That’s why lactic acid concentration is increased in muscle after strenuous exercise.

Question 34.
Observe the above graph of lactic acid accumulation in the muscles of an athlete and answer the following questions.
a) What was the concentration of lactic acid in the blood to start with?
Answer:
It is 20 mg/km³.

b) What was the greatest concentration reached during the experiment?
Answer:
101 mg/cm³.

c) If the trend between points C and D were to continue at the same rate, how long might it take for the original lactic acid level to be reached once again?
Answer:
55 minutes.

d) What does high level of lactic acid indicate about the condition of respiration?
Answer:
It indicates the accumulation of lactic acid in muscles through anaerobic respiration. The presence of lactic acid in the blood is the main cause of muscular pain and fatigue.

Question 35.
Describe the structure of human lungs with the help of a diagram.

Answer:

1. A pair of lungs is present in the chest cavity one on either side of the heart.
2. Lungs are spongy and elastic. They are enclosed by two membranes called pleura.
3. Space between the two membranes of pleura is filled with fluid. Pleura protects the lungs from injury.
4. Right lung is larger than the left lung.
5. Right lung is made of three lobes while the left lung has only two lobes.
6. Lung has several thousands of alveoli which are supplied with blood capillaries.
7. Pulmonary artery brings deoxygenated blood from heart to lungs.
8. After entering the lung, this artery divides into several arterioles and capillaries and supplies deoxygenated blood to alveoli.
9. Gas exchange occurs in the alveoli.
10. Oxygenated blood is carried from the lung to heart by the pulmonary vein.

Project work
Question 1.
Observe and analyse the questions in the table given below.

A) In which age group rate of heart beat is more?
B) In which age group rate of heart beat is less?
C) Why heart beat in Athletics is less?
D) What are reasons for more rate of heart beats differences between the newly born and children?
Answer:
A) In newly borned babies which are in 0 – 3 months of age group rate of heart beat is more i.e., 100 to 150 times.
B) In athletics the rate of heart beat is less i.e., 40 – 60 times / minute.
C) The heart of athlete pump more blood per beat due to increased cardio-vascular fitness in the structure of the heart. The muscles in the heart wall thicken and the heart pumps more blood with each beat.
D)

1. Mothers who have special medical conditions such as thyroid diseases or diabetes may give birth to new borns who are temporarily tachscardic from altered hormone and glucose levels. Tachycardia is a medical term for a very rapid heart beat.
2. Some infants are born with accessory electrical tissue in the heart causes epi¬sodes of rapid heart rate.
3. In wolf – parkinson syndrome – white syndrome there are extra cells and an ac-cessory path way, causing additional heart beats.

Question 2.
Observe the table given below and analyse the questions.

A) Why heart beat is less in animals with more weight?
B) Why heart beat is more in animals with less weight?
C) What is the relationship between weight of the body and rate of heart beat?
D) Why the weight of heart is less than body weight?
Answer:
A) The animals with more weight usually have weighted hearts. In one heart beat the large-sized hearts sends high amounts of blood to circulatory system. It takes time for the fulfilment of heart. Hence heart beat is less in animals with more body weight.
B) Usually the heart is very small in less weight animals. When the animal shrinks or contracts , its heart actually decrease the volume of blood proportionately. It can compensate for the reduced volume by increasing the rate at which it can supply blood to all body parts.
C) As the weight of the body of the animal increases the rate of heart beat per minute decreases. And also as the weight of the body decrease the rate of heart beat increases.
D) Usually the body of an organism is made by number of organs which makes the body functional. As all the body parts constitute the whole organism, the heart one of the organ is usually has less weight than body weight of an animal.

AP State Board Syllabus AP SSC 10th Class Biology Solutions Chapter 7 Coordination in Life Processes Textbook Questions and Answers.

AP State Syllabus SSC 10th Class Biology Solutions 7th Lesson Coordination in Life Processes

10th Class Biology 7th Lesson Coordination in Life Processes Textbook Questions and Answers

Improve your learning

Question 1.
What do you mean by hunger pangs?
Answer:

1. When glucose levels in the blood fall, hunger pangs occur in the stomach.
2. Ghrelin hormone is secreted in the stomach when it goes empty.
3. Ghrelin is secreted from certain cell walls of the stomach.
4. Hunger contractions (hunger pangs) start to occur in the stomach due to secretion of ghrelin hormone.
5. Hunger pangs continue up to 30 – 45 minutes.
6. An increase in Ghrelin levels results in sensation of hunger and motivation to consume food.

Question 2.
What are the organ systems involved in the digestion of food which we eat?
Answer:
The organ systems involved in the digestion of food are:

1. endocrine system,
2. nervous system,
3. muscular system,
4. circulatory system and
5. excretory system.

Question 3.
Rafi said smell also increases our appetite. Can you support this statement ? How?
Answer:

1. Yes. I support the statement made by Rafi that smell also increases our appetite.
2. When we smell, the air borne substances get dissolved in the watery film of nasal mucus.
3. The chemoreceptors which are otherwise called olfactory receptors present in the nose trigger signals in the form of nerve impulses to the brain where the smell is detected.
4. However interactions between the senses of taste and smell enhance our appetite.

Question 4.
Write a note on peristalsis and sphincter function in the stomach.
Answer:
A) Peristalsis functions in stomach:

1. Contraction and relaxation of the muscles present in the stomach bring in a wave-like motion called peristalsis.
2. The contraction of the stomach muscles squeeze and mix the food with the acids and juices of the stomach.
3. Mechanical mixing of food in stomach occurs by peristalsis. This allows the mass of food to further mix with the digestive enzymes.
4. Peristalsis in stomach is involuntary and under the control of the autonomous nervous system.

B) Sphincter functions in the stomach:

1. Pyloric sphincter is present at the opening of the stomach into the duodenum (small intestine).
2. The pyloric sphincter allows only small quantities of food into duodenum at a time.

Question 5.
Observe the given part of the digestive system. What is it ? What is it’s role during digestion ?
Answer:

1. The given part is the LARGE INTESTINE in the human digestive system:
   
2. If creates peristaltic waves to send waste material called stool or faeces into the rectum.
3. In the large intestine water and mineral salts are absorbed from the waste material.
4. The faecal matter containing indigested food material, bile pigments and dead bacteria is formed in the large intestine.
5. It is stored in the rectum and expelled out of the body through the Anus.

Question 6.
Give reasons.
a) If we press the tongue against the palate, we can recognize taste easily.
Answer:
Reason :

1. When the tongue is pressed against the palate, the food substance is pressed against the opening of the taste bud letting it to reach the taste cells and triggering taste signals.
2. Finally, the taste is recognized in the brain.

b) We can’t identify taste when food is very hot.
Answer:
Reason:

1. Most of the taste buds on the tongue are killed when the food is hot.
2. This prevents the person from identifying the taste.
3. The perception of taste decreases when the temperature of the food rises beyond 35°C.
4. But we don’t pay attention to it because we become worried about the burning feeling.

c) If glucose level falls in blood, we feel hungry. (OR) €EI June 2015
We feel hungry if the blood glucose level falls down. 03 June 2019
Answer:
Reason :

1. When glucose levels in the blood fall, we get hunger pangs in stomach.
2. Hungry feeling start to occur in the stomach due to hunger generating signals that the brain from the stomach due to the secretion of the hormone ‘Ghrelin’.

d) Small intestine is similar to a coiled pipe. (OR)
Why is the small intestine long and coiled?
Answer:
Reason :

1. The length of small intestine is 7 meters long.
2. It is coiled so as to fit in the human body.
3. It is coiled to increase surface area and maximum nutrient absorption when food passes through it.

e) Urination increases when we take lot of fluids.
Answer:
Reason:

1. When we take lot of fluids, the kidneys will efficiently throw the water out by forming more urine than usual.
2. When there is excess water in the body, the brain usually produces less of a hormone called vasopressin.
3. This in turn causes the kidneys to produce a lot of dilute urine, until excess water is removed.

f) The process of digestion goes on in a person whose central nervous system has been largerly affected.
Answer:
Reason :

1. The enteric nervous system embedded in the walls of the long tube of our gut or alimentary canal control gut functions often independently of the brain.
2. The mass of neural tissue of enteric nervous system filled with important neurotransmitters reveals that it does much more than merely handle digestion.

Question 7.
Write differences between the following:
a) Bolus – Chyme
b) Small intestine – Large intestine
c) Mastication – Rumination
d) Propulsion – Retropulsion
Answer:
a) Bolus – Chyme:

b) Small intestine – Large intestine:

c) Mastication – Rumination:

d) Propulsion – Retropulsion:

Question 8.
How can you say that mouth is a munching machine?
Answer:

1. Mouth plays a major role in changing the texture of food.
2. The circular muscles of the mouth enable the food to be pushed into the oral cavity and to be moved around.
3. The teeth grind, chew and shred the food.
4. The surface muscles of the jaw help in biting and chewing actions, while the deep muscles of the jaw move up, down, forward and backward during food mastication.
5. The teeth help in cutting and grinding while tongue movements evenly spread out the food and help in mixing it with saliva.
6. The muscles of the mouth enable the food to be pushed in the oral cavity and to be moved around.
7. By all this we can say that mouth is a munching machine.

Question 9.
What is mastication? Explain the role of different sets of teeth in this process.
Answer:
Mastication: Food can not be swallowed directly. So it must be grinded, chewed and shred. This process of grinding, chewing and shredding is called ’MASTICATION’.
Role of different sets of teeth in mastication:

1. In the oral cavity of human beings, 32 teeth and they are 4 different types to perform different functions.
2. They are a) Inscisors b) Canines c) Premolars d) Molars
   a) Inscisors: These are eight in number and have chisel shape. They have sharp edges and are specialized for cutting and biting the food.
   b) Canines: These are four in number and are with pointed edges- These are designed for piercing and tearing food.
   c) Premolars: These are eight in number and are also called cheek teeth. These are designed for crushing and grinding food.
   d) Molars: These are 12 in number. They are designed for crushing and grinding food.

Question 10.
During the journey of food from the mouth to stomach through oesophagus, how does muscular system coordinate in this process?
Answer:
Movement of food (bolus) from mouth to stomach through oesophagus is influenced by the coordination between muscular system and nervous system.
Muscular movement in mouth:

1. The circular muscles of the mouth enable the food to be pushed into the oral cavity and to be moved around.
2. The surface muscles of the jaw help in biting and chewing actions while the deep muscles move the jaw up and down, forward and backward during mastication.

Muscular movement in oesophagus:

1. The wall of the oesophagus is made up of two kinds of smooth muscles.
2. The inner layer consists of circular muscles and the outer layer is of longitudinal muscles.
3. Contraction of circular muscles lead to narrowing of the oesophagus behind the bolus. So the food is squeezed downwards.
4. Contraction of the longitudinal muscles in front of the bolus widens the tube, results in shortening of particular part of oesophagus.
5. In this way food moves easily and enters the stomach. ,
6. Contraction and relaxation of oesophagus muscles bring peristaltic movements.

Question 11.
Is there any reason for the intestine to be coiled with many folds ? In what way it is helpful during the process of digestion? (OR)
Small intestine is similar to a coiled pipe. Give reason.
Answer:

1. Yes, there is a reason for the intestine to be coiled with many folds.
2. The coiled and folded nature of intestine slows down the passage of food along the intestine and afford an increased surface area for absorption.
3. It also increases the surface area for the intestine to increase the absorption of nutrients through finger-like projections villi.
4. The folded and coiled intestine absorbs nutrients and water more than they breakdown.

Question 12.
What is the function of peristalsis in these parts?
a) Oesophagus b) Stomach c) Small intestine d) Large intestine
Answer:
a) Oesophagus:
Peristalsis helps in pushing the food, down the oesophagus into the stomach.

b) Stomach:

1. Peristalsis helps in storing food, breaking down food down and mixing it with juices secreted by stomach lining.
2. Peristalsis in stomach helps in partial digestion of food.

c) Small intestine:

1. Peristalsis pushes the digesting food through small intestine.
2. It helps to mix the chyme to help in the digestive process.
3. Peristalsis also helps in absorbing nutrients from the digesting food into the blood.

d) Large intestine:
Peristaltic movements help to propel feces along the large intestine through colon, to the rectum for expulsion from the body.

Question 13.
How can you justify the enteric nervous system as the second brain of the gut?
(OR)
Write about the nervous system present beneath the digestive system.
Answer:

1. The enteric nervous system, the second brain consists of sheaths of neurons embedded in the walls of the long tube of our gut, or alimentary canal.
2. The second brain measures about nine meters to end from the oesophagus to the anus.
3. The second brain contains some 100 million neurons, more than in either the spinal cord or the peripheral nervous system.
4. This multitude of neurons in the enteric nervous system enables us to “feel” the inner world of our gut and its contents.
5. Enteric nervous system contains mass of neural tissue filled with important neurotransmitters.
6. This reveals that it does much more than merely handling digestion or inflict the occasional nervous pang of hunger.
7. Enteric nervous system stimulates and coordinates the breaking down of food, absorbing nutrients and expelling of waste.
   Thus equipped with its own reflexes and senses, the second brain can control several gut functions often independently of the brain.
8. Several scientists also believe that the enteric nervous system is a way too complicated to have evolved only to make sure things move through and out of our gut smoothly.
9. Hence we can justify that the enteric nervous system as the second brain of the gut.

Question 14.
Rajesh feels hungry upon seeing food. Sheela says no more food as she is not hungry. What makes Rajesh hungry and what suppresses Sheela’s hunger?
Answer:

1. When glucose levels in the blood fall, we get hunger pangs in the stomach. Feeling hungry lies in the physiology of blood circulation.
2. The secretion of the hormone GHRELIN starts in the stomach when it goes empty.
3. Hunger contractions start to occur in the stomach due to hunger generating signals that reach the brain from the stomach due to ghrelin.
4. So Rajesh effected with secretion of ghrelin in his stomach and he felt hungry when he saw food.
5. Sheela was not affected with secretion of ghrelin in her stomach. She felt that her stomach is full.
6. When we feel the stomach is full and there is no need of food any more, another hormone LEPTIN is secreted that supresses hunger.

Question 15.
How are taste and smell related?
(OR)
What is the relationship between taste and smell?
Answer:

1. Taste and smell are closely related.
2. This close relationship is most readily seen in how we perceive the flavours of food.
3. Anyone with severe cough and cold cannot make out the difference in the taste of certain food items.
4. Actually, what is really being affected is the flavour of the food , or the combination of taste and smell.
5. That is because not only the taste but also the food odours are being defected.
6. However, interactions between the senses of taste and smell enhance our perceptions of the foods we eat.
7. Smell of the food flavour gives a similar taste to food.

Question 16.
List out the sphincter muscles of the food canal you have observed and give a brief description.
(OR)
What are the different types of sphincter muscles present in the digestive canal?
Answer:
There are different sphincter “muscles in the food canal. They are :

1. Esophageal sphincter
2. Cardiac sphincter
3. Pyloric sphincter
4. Anal sphincter and
5. Ileocecal value or sphincter.

1. Esophageal sphincter:

1. This allows entry of bolus into the oesophagus,
2. It also reduces back flow from the oesophagus to pharynx.

2. Cardiac sphincter:

1. It is present where oesophagus meets the stomach,
2. It’s location is almost directly in front of the heart,
3. It allows food from oesophagus into the stomach.

3. Pyloric sphincter:

1. It is present at the opening called pylorus, located at the end of the stomach,
2. Pyloric sphincter allows only small quantities of food into duodenum at a time.

4) Anal sphincter:

1. It is located at the anus, the end of the digestive system,
2. The release of waste is controlled partly, voluntarily by anal sphincter.

5) Ileocecal value:

1. It is situated at the junction of the small intestine (ileum) and the large intestine (colon),
2. It’s function is to limit the colonic contents into the ileum.

Question 17.
What happens if salivary ducts are closed?
(OR)
What happens if saliva is not produced by salivary glands?
Answer:
If salivary ducts are closed the following consequences may occur:

1. If salivary ducts are closed saliva will not release into the mouth, the mouth becomes dry.
2. We can’t taste the food.
3. Saliva secretes an enzyme called salivary amylase which breaks down the carbohydrates in food into dextrose and maltose sugar.
4. If saliva is not secreted in the mouth carbohydrates remains unchanged digestion will not completed.
5. Due to absence of saliva food will not get moistened, chewing and swallowing becomes difficult.
6. If salivary ducts are closed, the salivary glands become swollen and it leads to pain.

Question 18.
If size and shape of small intestine is like oesophagus what will happen?
Answer:

1. If size and shape of small intestine is like oesophagus the height of the person should be more than 22 feet as the length of the small intestine is about 22 feet. So it will not fit in the human body.
2. For the complete digestion of the food to occur, it has to stay in small intestine for 3 to 4 hours.
3. Otherwise digestion will not be completed and nutrients are not absorbed into blood . in the small intestine.
4. The tube like nature of small intestine as that of oesophagus will not provide increased surface area for complete absorption of nutrients.

Question 19.
Prepare a questionnaire to understand nervous coordination in the digestion process.
(OR)
What are the questions you are going to ask your teacher about nervous coordination in the digestion process?
(OR)
Prepare a questionnaire for an interview with a doctor to understand the nervous coordination in the digestion process.
Answer:

1. What is enteric nervous system?
2. Why the enteric nervous system is known as second brain?
3. How nervous system plays an important role in digestion of food?
4. Which nervous system controls the release of saliva from salivary glands?
5. Which cranial nerve controls the movement of muscles in the jaw?
6. The mechanism for swallowing is under the control of?

Question 20.
What experiment do you perform to understand action of saliva on flour? Explain it’s procedure and apparatus that you followed.
(Activity – 7)
(OR)
i) Explain the procedure followed in the experiment conducted to understand the action of saliva on starch.
ii) What apparatus and chemicals are used to do this experiment?
(OR)
Write the experiment you have performed in your school laboratory to know the action of Saliva on flour. How did you test the pH of Saliva?
(OR)
Explain the experiment conducted by your teacher in your class to show the action of saliva on the starch.
Answer:
Aim: To understand the action of saliva on flour.
Apparatus:

1. Two test tubes
2. Water
3. Ata flour
4. Water glass and
5. Iodine solution.

Procedure:

1. A test tube is taken and half of the test tube is filled with water.
2. A pinch of flour is added.
3. To mix flour with water, test tube as shaken.
4. Few drops of flour mixture is taken in a watch glass and test for the presence of starch by putting a drop of diluted tincture Iodine in it.
5. A blue black colour confirms the presence of starch.
6. Divide the mixture into two equal halves by transferring it to another test tube.
7. Both the test tubes have the same amount of solution.
8. Add a teaspoon of saliva to one of the test tube and mark it.
9. Do not add anything in the other test tube.
10. After 45 minutes add a drop of dilute Tincture Iodine solution to test tubes containing the solutions.

Observation:

1. Saliva containing flour mixture becomes slurry. It doesn’t show any change.
2. But in the second test tube with only flour mixture turns blue colour.

Conclusion:

1. Saliva in the test tube converts flour into sugar. So no change is observe here.
2. In the second test tube containing only flour mixture turns blue black.

(OR)
i) Answer:

1. Add a spoon of starch to the water taken in a test tube to make starch solution. Starch solution is divided into two equal parts in two test tubes.
2. Add a little saliva to one of the above test tube and the other without adding saliva and keep them a side for some time.
3. Add a drop of dilute iodine to both the test tubes. The test tube added with saliva doesn’t turns to blue black because the starch is broken down into smaller units called sugar by the saliva.
4. The other part which is not added with saliva turns into blue black, as it has starch without any change.
   So this experiment proves saliva converts complex carbohydrates into simple sugars.

ii) Answer:
Test tubes, water glass, flour, iodine, saliva.

Question 21.
Suggest a simple experiment to prove the role of palate in recognizing taste.
(OR)
How do you prove that palate has a role in recognizing taste?
(OR)
“Taste is connected to the tongue and palate”. Write an activity to prove it and write your observations.
Answer:
Experiment to prove the role of palate in recognizing taste
Aim: To prove the role of palate in recognizing taste.
Apparatus: Sugar crystals, Stop watch.
Procedure:

1. Place some sugar crystals on the tongue.
2. Keep mouth opened and see that tongue does not touch the palate.
   
3. Record the time from the moment we placed the crystals on the tongue till we get the taste by using stop watch.
4. Now repeat the test by placing the sugar crystals on the tongue pressing it against the palate.
5. Record the time from placing sugar crystals to getting the taste.

Observation: From the above activity we know that taste can be identified easily when the tongue is pressed against the palate.
Result: We can easily identify the taste of the substance we can identify the taste of it in lesser time.

Question 22.
Collect information related to feeling hunger from your school library and prepare a note on it.
Answer:

1. Generally we feel hunger when our stomach goes empty.
2. When our stomach goes empty Ghrelin hormone is released and it causes the feeling of hunger.
3. As well leptin hormone also released, but it causes the feeling of suppression of hunger.
4. Not only these, when we saw a colourful and good smelling food, automatically we feel hunger. So, the sight of seeing a good food also causes feeling of hunger.
5. If the food doesn’t have good colour, texture, good smell we can’t eat, even though it is a good food.
6. All the feelings towards food are recieved by our eyes, nose, tongue.
7. From these, information is sent to brain, from there signals are sent to stomach and causes feelings either positive or negative.
8. Hormones are also responsible for most of the feelings of hunger.

Question 23.
Draw the block diagram of showing sensation of taste from food material to brain.
Answer:

Question 24.
Draw a neatly labelled diagram showing a peristaltic movement in oesophagus Explain the importance of mucus on the walls of food pipe.
(OR)
In the food pipe, the food bolus is propelled into the stomach by peristaltic movement Represent this action with a diagram.
Answer:
Importance of mucus on the walls of food pipe :

1. The walls of the food pipe secrete a slippery substance called mucus.
2. Mucus lubricates and protects the oesophgeal walls from damage.
3. This helps the food bolus to slide down easily.
4. Besides this the saliva in the bolus also helps in easy movement.

Question 25.
Draw a schematic diagram of villus in small intestinp. Explain how digestive system coordinates with circulatory system.
(OR)
Draw the diagram of villi in small intestine and lable its parts.
Answer:
Coordination of digestive system with circulatory system :

1. After the completion of digestion in small intestine, it enters into the blood through villi.
2. In blood the digested food gets oxidised after that energy is released.
3. Releasing of energy from fot^d occur only when it enter into the blood.
4. So, there is a great coordination between digestive and

Question 26.
The mere smell or sight of food stimulates hunger . Describe the process through a neat diagram.
Answer:

1. The mere smell even the mere sight of delicious food stimulates the hunger.
2. When we smell, the air borne substances get dissolved in the watery film of nasal mucus.
3. The chemoreceptors in nose are otherwise called olfactory receptors which trigger signals in the form of nerve impulses to the brain where smell is defected.
4. The amount of the neurosecretory protein hormone ghrelin in the blood increases as a result of visual stimulation images of food.
5. Hunger contractions start to occur in the stomach due to hunger generating signals that reach the brain.
6. It is believed that the diencephalon in fore brain and vagus nerve (10th cranial nerve) plays an important role in carrying these signals to brain.
7. Hunger pangs continue up to 30-45 minutes.
8. Increase ¡n ghrelin levels results in sensation of hunger and motivation to consume food.

Question 27.
With the help of a diagram show the movement of food from mouth to the stomach. What muscles and nerves are involved in the movement of food and what is this action called as ? (OR)
Draw a diagram of peristaltic movement of food in oesophagus of elementary canal. Write how it performs.
Answer:
The muscles involved in movement of food from mouth to stomach :

1. The circular muscles of the mouth enable the food to be pushed into the oral cavity and to be moved around.
2. The surface muscles of the jaw help in biting and chewing actions and move the jaw up, down, forward and backward.
3. Contraction and relaxation of circular and longitudinal muscles in the oesophagus bring in a wave like motion that propels the bolus into stomach by the action called peristalsis.
4. As the food approaches the closed ring of pyloric sphincter the surrounding muscles relax and allow the food to pass.
5. The muscles of the upper part of the stomach have to relax and accept large volumes of swallowed material.

Nerves involved in the movement of food:

1. The fifth cranial nerve has been found to control the movement of muscles in the jaw.
2. Peristalsis in oesophagus is under the control of autonomous nervous system.

Question 28.
Prepare a cartoon on Pavlov’s experiment with a suitable caption.
Answer:

Question 29.
How do you appreciate stomach as a churning machine? How does this coordination
Answer:

1. The stomach acts like a churning machine, churning the food around to break it into even smaller pieces.
2. Mechanical mixing of food in stomach occurs by peristalsis, which is waves of muscular contractions that move along the stomach wall.
3. This allows the mass of food to further mix with the digestive enzymes.
4. Due to churning of food in stomach, a mixture that resembles thick cream called chyme is formed.
5. All the muscles in the stomach works with such a great coordination.
6. Hence we can call stomach as a churning machine.

Question 30.
There is a great variety in diversified life processes, express your feelings in the form of a poem.
Answer:

POEM
Life is a process of discomfort and pain.
Learn to handle it all with courage and sane
Remember the bliss waiting for you
Nutrition, excretion, respiration all are essential in our life.
Reproduction makes our species go on and on forever.
Autotrophs and heterophs are brothers.
Depend on each other In a systematic way.
So have courage to learn more tricks.
Search for happiness.
In life that survive.

Question 31.
Suggest any two important habitual actions to your friend while eating food, keeping in view of this chapter.
Answer:

1. Masticate the food thoroughly in the mouth.
2. Do not swallow food without chewing properly or do not eat in hurry.
3. Eat small quantities of food at regular intervals for efficient digestion and absorption of nutrients.
4. Eat the food that emit good smell and has good taste to eat.
5. Do not eat too hot and too cold items.

Fill in the blanks.

1. 3:2:1:2 is the ratio of our dentition. Here 1 represents ———–.
2. Large protein molecules are broken down in ———– of digestive tract.
3. ———– is the strong acid which is secreted during digestion.
4. Olfactory receptors present in ———– triggering signals to brain.
5. pH of saliva is ———– in nature.

Answer:

1. Canine
2. Stomach
3. HCl
4. Nose
5. Alkaline nature

Fill in the blanks with suitable words given below.

Fluctuations of hormone —–(i)—– levels results in sensation of hunger and motivation of consuming food. When you feel your stomach is full and there is no need of food any more. Another hormone —–(ii)—– that gets secreted suppresses hunger. When we take food into the mouth it has to be chewed thoroughly. For this purpose the —–(iii)—– muscles help in chewing actions, while the —–(iv)—– muscles of the jaw moves the jaw up,down, forward and backward during food mastication. The —–(v)—– nerve controls the muscles of the jaw. Under the action of —–(vi)—– nervous system Saliva is released by the salivary glands moistens the food to make chewing and swallowing easier. The salivary —–(vii)—– in the saliva breaks down the starch into sugars. As a result of chewing the food is transported into the oesophagus by the action of swallowing which is coordinated by the swallowing centre in the —–(viii)—– and the —–(ix)—–. The tongue which is gustatory recognizes the taste and —–(x)—– nerve plays an important role in sensation of taste.

Choose the right ones.
i) leptin, ghrelin, gastrin, secretin.
ii) ghrelin, leptin, secretin, gastrin.
iii) deep muscles, surface muscles, circu lar muscles, striated muscles.
iv) surface muscles, deep muscles, neck muscles, long muscles.
v) fifth cranial nerve, second cranial nerve, fifth facial nerve, spinal nerve.
vi) central nervous system, peripheral nervous system, autonomous nervous system.
vii) lipase, sucrase, galactase, amylase.
viii) medulla oblongata, cerebrum, 8th spinal nerve, cranial nerve, 7th cranial nerve.
ix) Pons varoli, brain stem, medulla oblongata, mid brain.
x) 6th cranial nerve, 5th cranial nerve, 10th cranial nerve, optic nerve.

Answer:
i) ghrelin
ii) leptin
iii) surface
iv) deep
v) fifth cranial
vi) autonomous
vii) amylase
viii) medulla oblongata
ix) brain stem
x) fifth cranial nerve

Choose the correct answer.

1. In which of the following situations you can taste quickly? [ ]
   A) Put sugar cristals on tongue
   B) Put sugar solution on tongue
   C) Press the tongue slowly against the palate
   D) Swallow directly without grinding and shredding
   Answer: C
2. Peristalsis is because of [ ]
   A) Contraction of longitudinal muscles
   B) Contraction of circular muscles
   C) Under control of autonomous nervous system
   D) Digestive secretions
   Answer: C
3. Sphincter that helps in opening of stomach into duodenum [ ]
   A) Cardiac
   B) Pyloric
   C) Anal
   D) Gastric
   Answer: B
4. Glucose and amino acids are absorbed through the following part of villus [ ]
   A) epithelial cells
   B) blood capillary
   C) lymphatic vessel
   D) all
   Answer: A
5. The region in brain portion that controls hunger signals [ ]
   A) medulla
   B) diencephalon
   C) cerebrum
   D) mid brain
   Answer: B
6. Human organism is an internal combustion machine because of …. [ ]
   (OR)
   Human being is an “Internal combustion machine” because he/she
   A) assimilation of energy from food
   B) liberate CO₂ during respiration
   C) expel waste food at the end state of digestion
   D) secrete powerful digestive juices
   Answer: A

10th Class Biology 7th Lesson Coordination in Life Processes InText Questions and Answers

10th Class Biology Textbook Page No. 145

Question 1.
How do we know that we need food?
Answer:
When we feel hungry then we know that we need food.

10th Class Biology Textbook Page No. 146

Question 2.
What plays a major role to identify stale food?
Answer:
Smell or odour plays a major role to identify stale food.

Question 3.
If you are having a tasty dish do you think the smell of it increases your appetite?
(OR)
Do the smell of tasty dish increases our appetite?
Answer:
Yes, the smell of tasty dish increases our appetite.

Question 4.
What are your observations after chewing cumin, sounf, potato and apple?
Answer:
If we chew cumin, sounf, potato and apple we observe in order to taste the food material the food should dissolve in saliva.

10th Class Biology Textbook Page No. 148

Question 5.
Are there any other sensation that affect taste?
Answer:
Temperature (hotness), coldness are the sensations that affect taste.

Question 6.
What happens to your taste sensation while sipping hot milk or tea?
Answer:
We find something more tasty while we sipping hot milk or tea.

Question 7.
What do you think could be the range of temperature for us to relish food items?
Answer:
30°C to 35°C could be the range of temperature for us to relish food items.

10th Class Biology Textbook Page No. 149

Question 8.
What do you think that would happen if the salivary glands did not function in our mouth?
Answer:

1. If the salivary glands do not function in our mouth, saliva will not release and the food do not get moistened and chewing it is difficult.
2. The taste of the food cannot be identified.
3. Carbohydrates in the food cannot be broken down and changed to dextrose and maltose molecules.

Question 9.
Suppose your taste buds were affected what would happen to your interest in haying food?
Answer:
If my taste buds were affected I cannot identify the taste of food and also loose interest in having food.

10th Class Biology Textbook Page No. 151

Question 10.
Does the level of saliva secretion change due to presence of food in the mouth?
Answer:
Yes, the level of saliva increases due to the presence of food in the mouth.

Question 11.
Can the process of chewing go on in the absence of saliva?
Answer:
Yes, the process of chewing go on in the absence of saliva. But it is very difficult to chew food and swallow it.

Question 12.
Does the saliva have any other roles to play?
Answer:
The enzyme present in saliva that is salivary amylase converts large molecules of carbohydrates into small molecules of sugar like maltose and dextrose.

Question 13.
What is the use of such an increase in surface area of food?
Answer:
It helps in more surface area for the enzyme to act.

Question 14.
What about the nature of medium for salivary amylase to act on food component?
Answer:
The nature of medium for salivary amylase to act on food component is alkaline.

Question 15.
If we swallow food material directly without mastication what will happen?
Answer:
If we swallow food material directly without mastication, the food will not get digest easily and completely.

Question 16.
Do you think the pH of our mouth changes?
Answer:
Yes, the pH of our mouth changes from acidic to alkaline by the release of saliva from salivary glands.

10th Class Biology Textbook Page No. 152

Question 17.
What are the different systems that contribute to the proper functioning of digestion in the mouth?
Answer:
Endocrine, muscular, nervous systems contribute to the proper functioning of digestion in the mouth.

Question 18.
After the digestive process in the mouth where does the food move to?
Answer:
After the digestion in the mouth the food move to oesophagus.

10th Class Biology Textbook Page No. 153

Question 19.
What are the systems that come into play for swallowing food?
Answer:
Skeletal system, nervous system and digestive systems come into play for swallowing food.

Question 20.
What does the schematic diagram tell us about the oesophagus?
Answer:
The schematic diagram of the oesophagus tells about its structure, secretion and function.

Question 21.
What kind of the tube is oesophagus?
Answer:
Oesophagus is a muscular and an elastic tube.

Question 22.
How does mucus help in passage of food?
Answer:
Mucus helps in lubricating and protecting the oesophageal wall and helps the bolus to slide down easily in the oesophagus.

10th Class Biology Textbook Page No. 154

Question 23.
What makes the movement of the food bolus in the oesophagus easy?
Answer:

1. Mucus helps the food bolus to slide down easily.
2. Peristaltic movements of the walls of oesophagus also make the movement food bolus in the oesophagus easy.

Question 24.
Why do you think the stomach is structured like a bag rather than a tube like an oesophagus?
(OR)
Why stomach is structured like a bag rather than like a tube?
Answer:

1. The food taken has to remain in the stomach for a long time for proper digestion with digestive juices and enzymes.
2. Different kinds of muscles churns the food by contraction and relaxation to form chyme.
3. If it was like a tube the food would just pass down without under going much changes and cannot remain in the stomach for long time.

Question 25.
What sets such processes into action?
Answer:

1. When the food is in the oral cavity, the nerves in the cheek and tongue are stimulated.
2. These carry messages in the form of nerve impulses to the brain.
3. They messages are transmitted from the brain, to the wall of the stomach, and stimulate the gastric glands to produce gastric juice.

10th Class Biology Textbook Page No. 155

Question 26.
What stimulates stomach muscle into action?
Answer:
The nervous system stimulates stomach muscle into action.

Question 27.
What causes the stomach to churn and mix the food?
Answer:
The contractions of the stomach muscles squeeze and mix the food with the acids and juices of the stomach.

Question 28.
Why should only a small quantity of food be passed from stomach to duodenum?
Answer:
For the complete digestion of chyme, only a small quantity of it be passed from stomach to duodenum.

Question 29.
What is involved in bringing about peristalsis?
Answer:
Contraction and relaxation of the muscles present in various parts of gut bring about peristalsis.

Question 30.
What is the direction of peristalsis? Which end of the gut does it begin?
Answer:
The direction of peristalsis is forward direction that is from mouth to anus.

Question 31.
What happens if the direction of peristalsis is reversed?
Answer:
If the direction of peristalsis is reversed the food present in the gut moves backwards.

10th Class Biology Textbook Page No. 157

Question 32.
Why do you think small intestine is long and coiled?
Answer:
The small intestine is long and coiled because the food has to stay for more time for complete digestion and absorption.

Question 33.
What process is involved in this process of absorption?
Answer:
Selective absorption of nutrients by the villi of small intestine is involved in absorption.

Question 34.
What is the relation between finger-like structures and paper folds?
Answer:

1. Finger-like structures increase the surface area.
2. The space inside the paper folds is very much high. So area is increased.
3. So increase in surface area is the relation between finger-like structures and paper folds.

Question 35.
What systems do you think are working together?
Answer:
The digestive system and circulatory system are working together.

Question 36.
Do you think those systems work together in the whole length of the digestive canal? Why / Why not?
Answer:
No, these systems are not working together in the whole length of the digestive canal. The digested food material is absorbed only in the small intestine but not elsewhere in the gut.

10th Class Biology Textbook Page No. 158

Question 37.
Often you may have experienced that if you have tension for some reason you start having loose motions. What does this show us?
Answer:
If we are tensed for some reason, the enteric nervous system or second brain loses control over the gut. Hence without our intervention, loose motions occur.

10th Class Biology Textbook Page No. 159

Question 38.
What moves out of the gut?
Answer:
The indigested food material moves out of the gut.

Question 39.
Two major pathways of waste expulsion are shown above. Which of the two do you think happens exclusively through the gut?
Answer:
Indigested food matter is expelled in the form of stool from the gut.

Question 40.
What controls the exit of stools from the body?
Answer:
The two muscular layers present In the anal sphincter control the exit of stools from the body.

Question 41.
Do you think the control is voluntary? Why / Why not?
Answer:
Yes, the control is voluntary in adults and it is involuntary in infants.

Question 42.
Did we have a sphincter in any other part of the digestive canal? Where was it?
Answer:
Yes. We have a sphincter at the opening where stomach opens into duodenum (small intestine).

10th Class Biology Textbook Page No. 160

Question 43.
What is the fate of the digested substances that move into blood from the intestine?
Answer:
The digested substances reach each cell of the body through circulatory system. There it gets oxidised and release energy.

Question 44.
Where is the energy stored?
Answer:
The energy is stored in the cells as ATP.

Question 45.
Which system do you think will remove the excess salts from our body?
Answer:
The excretory system remove the excess salts from our body.

Question 46.
What would be the path of salt removed from gut to the outside of our body?
Answer:

1. The digested food containing salts will be absorbed into the blood stream in small intestine.
2. The circulatory system supplies this to kidney through renal artery.
3. In the kidney salts are filtered and sent out of the body along with urine.
4. Some of the salts also supplied to the skin. They will be sent out of the body in the form of sweat.

10th Class Biology 7th Lesson Coordination in Life Processes Activities

Activity – 1
Observe the following table, identify and tick those options that you think makes you feel hungry.
Table

i) What stimulates hunger?
Answer:
Smell of food, sight of food and need of food stimulates hunger.

ii) What would be the result of stimulation of hunger?
Answer:
Hunger pangs occur in the stomach.

iii) Which system do you think would send the signals to make us realize that we are hungry?
Answer:
Nervous system.

iv) What kinds of controls are exercised during sensation of hunger? Are they hormonal or nervous or both?
Answer:
They are both hormonal and nervous.

v) Can you suggest any four systems involved in the process of generating hunger sensation?
Answer:
Digestive system, Endocrine system, Circulatory system and Nervous system.

Activity – 2
Observation of how our taste is affected by the sense of smell. (OK) How our taste is affected by the sense of smell?

1. First, close your nose with your fingers.
2. Pop in some zeera in your mouth and chew it for some time.
3. After that chew some sounf.
4. Could you recognise the taste?
5. How long it taken to know the taste?
6. After sometime wash your mouth and repeat the activity by chewing a piece of an apple followed by a potato (remember to close your nose)

Could you know the taste of both or did it taste the same? Why?
Answer:
No, because taste buds couldn’t send the taste signals to brain.

Observation :

1. We can taste the food that is in the form of liquid only.
2. Only after the dissolved food enters into the cup like taste buds, the sense of taste is carried to the brain for analysis. Then only we will know the taste of food material.
3. Similarly olfactory receptors which trigger signals in the form of nerve impulses to the brain where smell is detected.

i) What happens when we put a food material in our mouth?
Answer:
Our mouth salivates.

ii) Name the parts in the mouth that help us to taste food.
Answer:
Papillae (taste buds), palate.

Activity – 3

1. Take a pinch of asafoetida powder/garlic and rub it on hand kerchief/tissue paper.
2. Close your eyes and smell it.
3. Then try to identify taste of different types of food materials with the help of your friend.

i) Does garlic have a stronger scent than apple? How do you think the stronger scent affect your sensation of taste?
Answer:
Yes, garlic have a stronger scent than apple. The stronger scent motivate us to eat different types of foods.

ii) How many food materials you have identified correctly?
Answer:
Seven.

iii) Write a few lines on the relation between smell and taste.
Answer:

1. Taste and smell are intimately entwined. This close relationship is most apparent in how we perceive the flavour of food.
2. Taste itself is focussed on distinguishing chemicals that have sweet, salty, sour, bitter or umami taste.
3. However interactions between the senses of taste and smell enhance our perceptions of the foods, we eat.

iv) Have you ever felt that a particular food is tasty just by looking at it?
Answer:
I felt so many times. In general, we prefer the food material, which is attractive to our eyes and flavour to nose, then we taste it.

Activity – 4
What is the role of different parts of the mouth in helping us to taste keeping sugar crystals over the tongue?

1. Place some sugar crystals on the tongue and keep mouth opened and see that your tongue dosen’t touch the palate.
2. Record the time from the moment you placed the crystals on your tongue till you got the taste by using stop watch.
3. Now repeat the test by placing the sugar crystals on the tongue and pressing it against the palate.
4. Record the time from placing sugar crystals to getting the taste. Or put a drop of sugar solution on your tongue using a dropper.

Observation :
Based on the above activity we know that taste can be identified easily when the tongue is pressed against the palate.
i) Can we taste on dry tongue?
Answer:
No. We can’t taste on dry tongue.

ii) Which way helped you taste faster? Why?
Answer:
Taste can be identified faster when the tongue is pressed against the palate.
When the tongue is pressed against the palate the food substance is pressed against the opening of the taste bud letting it reach taste celjs triggering taste signals. Finally the taste is recognised in the brain.

Activity – 5
How do you show that the breakdown of food by using the model of chalk piece kept in vinegar?

1. Break a piece of chalk into two halves.
2. Crush one half to tiny pieces leaving the other as it is.
3. Take two small mineral wafer bottles QA ltr bottle) cut them into two equal halves and discard the upper portion.
4. Now we have two beakers from the lower cut portion.
5. Fill them half with vinegar and add the crushed chalk to one beaker and the other uncrushed half chalk to the other.
6. Observe them after half-an-hour or so.

i) Which one dissolved faster the crushed chalk or the whole one?
Answer:
Beaker with crushed chalk dissolved faster than the whole one.
This experiment tells us the need of mechanical crushing of food the mouth to increase surface area for action of substances that aid in digestion.

ii) How does this process of mechanical crushing go on in the mouth?
Answer:
Mechanical crushing of food goes in the mouth by chewing.

iii) Which parts in the mouth are involved in this?
Answer:
Teeth and tongue.

iv) What are the systems involved in this process?
Answer:
Digestive system, Nervous system, Muscular system.

Activity – 6
Observe the diagram and answer the questions and fill the table.
i) Observe the model or chart of jaw, on the basis of the figure try to guess what are the functions molars could be?
Answer:
Chewing and grinding.

ii) What do you think could be the function of inscisors?
Answer:
The function of inscisors is biting the food.

iii) Which set of teeth helps in grinding food?
Answer:
Premolars and molars.

iv) Which set helps in tearing food?
Answer:
Canines help in tearing food.

v) What is your dental formula?
Answer:
is the dental formula.

Table

Activity – 7
Testing pH of mouth at intervals of one hour.

1. Collect a strip of pH paper with a colour chart from a chemistry teacher.
2. Take a small piece of the pH paper and touch it to your tongue.
3. Match the colour with the colour chart and note the pH.
4. Take some readings after having your food at lunch break.
5. Compare your readings with that of your friend.
6. Take at least 4 readings.

Table

i) What is the usual range of pH of your mouth Acidic (or) Basic
Answer:
The usual range of pH of our mouth is more or less 6.5. At low level the saliva is acidic and at high level it is basic.

ii) Did you observe any change in pH after eating? What may have caused the change?
Answer:
Yes, 1 observed the change in pH. Bicarbonates in saliva changed that into basic.

iii) In what kind of pH do you think salivary amylase acts well?
Answer:
In the pH range 7.2 to 7.4 it acts well in alkaline medium.

iv) Does this type of food have any role to play on the pH of our mouth?
Answer:
If the food that enters is acidic it will be converted into basic stuff and then it is swallowed.
Based on the above tests we know that salival secreted causes the medium to change to alkaline as it aids in action salivary amylase.

Activity – 8
Making a model of oesophagus to observe how bolus moves forward.

1. Take a piece of waste cycle tube and insert one or two potatoes into it.
2. Lubricate the inner side of the tube with oil.
3. In the same way smear oil over potatoes.
4. Insert oil coated potatoes in the tube.
5. Now try to push the potatoes by squeezing the tube.

i) How do you squeeze the tube to make the potatoes pass through?
Answer:
By pushing the potato from behind.

ii) Do you think that the muscles in the wall of the oesophagus have to do something like this?
Answer:
Yes.

iii) How did oil help you in pushing the potatoes through the pipe?
Answer:
Oil acted as a lubricant to push the potato easily in the forward direction.

Activity – 9
How is the stomach protected from the secretions of its own acids?

1. Take two similar green leaves.
2. Grease one leaf with petroleum jelly, leave the other free.
3. Add 1 or 2 drops of some weak acids on both the leaves.
4. Observe them after half-an-hour or so and write your observations.

i) Which leaf was effected by the acid?
Answer:
The leaf to which petroleum jelly was not applied.

ii) What kind of change did you observe in the leaves?
Answer:
The colour of the leaf changes.

iii) What saved the other leaf from the effect of acid?
Answer:
Petroleum jelly.
From the above activity we can conclude that mucus secreted by the walls of stomach protects stomach from the harmful effects of hydrochloric acid.

Activity – 10
Paper tube and folded papers.

1. Provide students with a piece of paper.
2. Let them calculate the area of one side of the paper and make a roll of it.
3. Try to fill the tube by inserting few folded papers as much as possible in it.
4. Pull out the papers from the tube, unfold them and find out the whole area of the papers.

i) Compare the area of the folded papers with that of the roll. Do you find any increase in the area ? If so try to find out the reasons?
Answer:
Area is increased. The space inside the folded papers is very much high. So we can insert as many folded papers as we could.
From the above activity we can infer that the inner surface of the small intestine contains thousands of finger-like projections called villi which increase the surface area of absorption of nutrients in small intestine.

AP State Board Syllabus AP SSC 10th Class Biology Solutions Chapter 6 Reproduction – The Generating System Textbook Questions and Answers.

AP State Syllabus SSC 10th Class Biology Solutions 6th Lesson Reproduction – The Generating System

10th Class Biology 6th Lesson Reproduction – The Generating System Textbook Questions and Answers

Improve your learning

Question 1.
Why do fish and frog produce a huge number of eggs each year?
Answer:

1. External fertilisation occurs in fish and frog.
2. The female lays a vast number of eggs in water and male releases some millions of sperms on to them in water.
3. Eggs may be carried to a long-distance by water currents or they may be eaten by predators.
4. So fertilisation is a chance factor and controlled by nature.
5. Fertilisation occurs externally hence it is inevitable to give rise to vast number of eggs by fish and frog.

Question 2.
Give examples and explain what is meant by external fertilisation?
Answer:

1. Fusion of the male and female gametes is called fertilisation.
2. The fertilized egg (ovum) is called zygote.
3. If the fertilisation occurs outside the body of the female organism then it is called external fertilisation.
4. External fertilisation is seen in fish, frog and earthworm, etc.

Question 3.
Write the differences between
a) Grafting – Layering b) Stamen – Carpel.
Answer:
a) Differences between Grafting and Layering.

b) Differences between Stamen and Carpel.

Question 4.
Describe the mode of fertilization in plants with a diagram.
Answer:

1. Fertilisation is the process of fusion of male and female gametes.
2. For the fusion of male and female gametes pollen grains have to reach the surface of the stigma. This is called pollination.
3. Pollen grains received by the stigma germinate and give rise to pollen tubes. Only one pollen tube finally reaches the embryo-sac.
4. This tube will have two male nuclei, which migrate to the tip of the pollen tube at the time of fertilization.
   
5. Usually the pollen tube enters the ovule through micropyle and discharges the two male gametes into its embryo-sac.
6. One male nucleus (n) or (gamete) approaches the egg and fuses with it to form a diploid (2n) zygote. This is first fertilisation.
7. The other male nucleus (n) or (gamete) reaches the secondary nucleus (2n) and fuses with it to form the endosperm nucleus which will be triploid. This is second fertilization in the embryo-sac.
8. Thus double fertilisation occurs in embryo-sac which is unique in flowering plants.

Question 5.
What are the different modes of asexual reproduction? Cite them with examples.
Answer:
Asexual reproduction takes place by six different methods. They are:

1. Fission
2. Budding
3. Spore formation
4. Regeneration
5. Fragmentation and
6. Vegetative propagation.

1. Fission: Single-celled organisms split into two equal offsprings or more offsprings. Ex: Paramoecium, bacteria.

2. Budding: A growth on the body as a bud grows to form identical copy of parent. Ex: Yeast.

3. Spore formation : Spores are produced in the sporangium.
Ex : Rhizopus, mucor, bacteria, ferns and mosses.

4. Regeneration :
a) Ability of organisms to give rise to new individual organisms from their body parts.
b) That is if the individual is some how cut or broken up into many pieces, many of these pieces grow into separate individuals.
Ex: Hydra and Planaria.

5. Fragmentation:
a) In multicellular organisms with relatively simple body organisation breaks up into smaller pieces upon maturation.
b) These pieces of fragments grow into new individuals.
Ex: Flatworms, Spirogyra, moulds, lichens.

6. Parthenogenesis: In the process generally the female gametes or ova develop into zygote without fertilization.
Ex : Bees, ants and wasps.

7. Vegetative propagation: When a vegetative part like stem, root and leaf can produce a new organism it is called vegetative propagation. It is of two types.
a) Natural propagation:
Bryophyllum Dahlia, Carrot, Radish
b) Artificial propagation:
i) Layering: Eg: Nerium, Guava, Orange, Rose
ii) Cutting: Eg: Rose, Hibiscus, Sugarcane
iii) Grafting: Eg: Sapota, Guava, Mango, etc.

Question 6.
In what ways does sexual reproduction differ from asexual one? State at least three reasons.
(OR)
What are the differences between sexual and asexual reproduction?
Answer:

Apart from the above differences Sexual and Asexual reproduction differs in the following ways:

1. The unit of reproduction in sexual reproduction is gamete whereas in asexual repro-duction it may be whole parent body or bud or a fragment or a single somatic cell.
2. Sexual reproduction need more time to complete and it is less time in asexual reproduction.

Question 7.
How are sperm cells adapted for their function?
Answer:

1. Sperm cell is adapted to its function by carrying genetic information to an egg.
2. Its body consists of four parts :
   1. Head
   2. Neck
   3. Middle piece and
   4. Tail.
3. Sperm has a streamlined body that allows it to move quickly.
4. Nucleus is present in the head.
5. Special structure on the head called acrosome helps in penetrating the ovum during fertilisation.
6. The head of sperms also contain enzymes to breakdown and digest the zone on the egg through which it penetrates and fertilise it.
7. Large number of mitochondria are present in the mid-region, so it is able to produce a lot of energy in order to operate tail.
8. Its tail allows it to swim towards the egg for fertilisation.

Question 8.
The menstrual cycle prepares the uterus for a fertilised egg. How long is an average menstrual cycle from start to finish?
Answer:

1. The cycle of changes that occur in the female reproductive system is called menstrual cycle.
2. The average menstrual cycle from start to finish is 28 days long.

Question 9.
When the foetus is growing inside the uterus it needs nutrients? What provides these nutrients?
Answer:

1. When the foetus is growing inside the uterus it needs nutrients for its growth and development.
2. These nutrients are provided by the mother’s blood through a special structure called placenta.
3. Placenta is a tissue formed by the cells from the embryo and the mother.
4. It is formed around 12 weeks of pregnancy and becomes an important structure for nourishment of the embryo.
5. The foetus is connected to placenta in mother’s body through umbilical cord.

Question 10.
Which type of substances are absorbed by foetus from the mother?
Answer:

1. The digested food from the mother travel through the mother’s blood stream and exchange to the blood stream of the foetus through the placenta.
2. In addition to ingested food the mother’s body continuously breakes down muscles, fat and bones.
3. Releasing proteins, fat and calcium to the mother’s blood that can be absorbed through the placenta to provide nutrients to the foetus.
4. Some hormones also transfer to baby.

Question 11.
What is the job of Amniotic sac?
Answer:

1. The amniotic sac is a bag of fluid inside a women’s womb (uterus) where the embryo and foetus develops and grows.
2. The cavity within the amnion becomes filled with fluid called amniotic fluid.
3. The embryo or unborn baby floats and moves in the amniotic fluid.
4. Amniotic sac and amniotic fluid give protection against minor mechanical injury.
5. This fluid also provides a stable temperature and assists in maintaining a consistent body temperature for the unborn child.

Question 12.
What are the advantages of sexual reproduction?
(OR)
What are uses of sexual reproduction?
Answer:
Advantages of sexual reproduction:

1. Sexual reproduction promotes diversity of characters in the offsprings by providing genetic variation.
2. It plays an important role in the origin of new species have different characters.
3. This genetic variation leads to the continuous evolution of various species to form better and still better organisms.
4. Sexual reproduction influences in diversity of characters in offsprings.
5. It helps to maintain the continuty of organisms.
6. It leads to new generation to tolerate adverse or diseased conditions.
7. It helps the spreading of population to new areas.

Question 13.
How does reproduction help in providing stability to population of species?
Answer:

1. The reproduction is directly linked to the stability of the population of species because it helps in replacing the lost or aging population with the new population and thus ensures the survival of the species.
2. The process of reproduction ensure continuity of life on earth.
3. In the absence of reproduction one particular species will disappear with time.
4. Reproduction induces variations in the population which help the population to tide over adverse environmental conditions and adapt to changing environment.
5. Reproduction also helps to generate copies of individuals which are suited to a particular environment.

Question 14.
Write the differences between mitosis and meiosis.
Answer:

Question 15.
What happens to the wall of the uterus during menstruation? (OR)
What changes occur in the wall of the uterus during menstruation?
Answer:

1. During the early stage of menstruation the cells in the wall of uterus increase in number by repeated mitotic divisions.
2. The inner lining of uterus becomes thick and soft with lot of blood capillaries in it.
3. These changes in the uterus are necessary because in case the ovum released by the ovary gets fertilised by the sperm, then the uterus has to keep this fertilised ovum for further development and supply it with food and oxygen etc.
4. If fertilisation does not occur the additional growth of the uterus is detached and expelled along with some amount of blood.

Question 16.
“All unicellular organisms undergo only mitotic cell division during favourable conditions” – Do you support this statement? Why?
Answer:

1. Unicellular organisms undergo mitotic cell division not only during favourable conditions but also in unfavourable conditions.
   So I don’t support the given statement.
2. When the organism finds favourable conditions it deserves to perform division called Fission. Ex: Amoeba.
3. Sometimes scarcity of food or to save it life, some organisms undergo mitotic cell division.
4. Organisms like paramoecium undergo a type of sexual reproduction called conjugation during unfavourable conditions.

Question 17.
What would be the consequences if there is no meiosis in organisms that reproduce sexually?
(OR)
What happens if Meiosis does not take place in reproductive cells?
Answer:

1. If meiosis did not occur, a fusion of gametes would result in a doubling of the chromosomes for each successive reproduced generation.
2. For example, in case of man egg cells and sperm cells like other cells must contain 46 chromosomes.
   
3. This results in the formation of abnormalities in each generation.
4. If meiosis did not occur, there is no genetic variation in the offsprings produced by random fusion of the gametes.
5. New characters will not appear in the offsprings.
6. The process of evolution will be stopped.

Question 18.
Vicky’s father wants to grow a single plant having two desirable characters colourful flowers and big fruits. What method will you suggest to him and why?
Answer:

1. I will suggest the method of grafting to him.
2. Grafting enables us to combine the most desirable characteristics of two plants into a single plant with colourful flowers and big fruits.
3. By grafting method, a very young scion can be made to flower and produce fruits fast when it is grafted to the stock.
4. Vicky’s father can grow one of the two plants as stock and second plant can be graft to some of its branches as scions.
5. Then he can get the plant with both the desirable characters.

Question 19.
Uproot an onion plant and take a thin section of its root tip. Stain it and observe under the microscope. Draw as you see and identify the stages of the cell division.
Answer:

Question 20.
Visit a nearby village and collect information on how farmers grow sugarcane, flowering plants like chrysanthemum, primerose and vegetables like stem tubers, plump gourd (dondakaya), etc. Make a report and present in class.
Answer:
Report on growing methods of various plants :

Question 21.
Collect the information from school library or using internet what vegetative methods are followed in your district as well as in your state to propagate various plants of economic importance. Represent it with a graph.
Answer:
Vegetative methods followed in our district as well as in our state to propagate various plants of economic importance.
I) Natural vegetative propagation: In this method of vegetative propagation, a part of the plant which may be stem, root-leaf or flower gets detached from the body of the mother plant.

1. Vegetative propagation: Roots of radish, carrot, dahlia develop adventious buds which grow into leafy shoots.
2. Vegetative propagation by stems: Stolons – Vallisneria, offsets – Eichhornia, Rhizome – Banana, Ginger Bulbs – Alliumcepa (Onion); Corn – Colacasia; Tuber – Potato.
3. Vegetative propagation by leaves: Bryophyllum.
4. Vegetative propagation by modified flowers (Bulbils): Agave.

II) Artificial vegetative propagation: Certain flowering plants have the capacity to develop a part of their somatic body into a new independent plant. In artificial vegetative propagation such plants are identified and special techniques are applied to obtain new independent plant.

1. Cutting (Stems): Sugarcane, Roses, Hibiscus, Citrus plants.
2. Cutting (Root): Lemon, Tamarind.
3. Layering: Jasmine, Strawberry, Gooseberry.
4. Grafting: Rubber, Apple, Pear, Citrus, Mango, Guava.
5. Propagation by tissue culture technique: Lily, Rose, Magnolia, Fern, Banana for micropropagation, a small amount of tissue from a suitable part of the parent plant is excised and grown on a nutrient medium under aseptic conditions.

Question 22.
Make a flow chart to show the cell cycle and explain cell division describing different stages of mitosis.
Answer:

Different stages of mitotic cell division:

Question 23.
Draw neat labelled diagrams of male and female reproductive systems of plant.
Answer:

Question 24.
Observe the following part of flowering plant and prepare a note.
Answer:
The given diagram is the structure of ovule which is present in the ovary (carpel) of plant.

1. An ovule is an egg shaped structure attached by a stalk (Funicle) to the inner side of the ovary.
2. Depending upon the species of plant involved, an ovary may have one, two, several or even hundreds of ovules.
   
3. At the centre of each ovule is a microscopic embryo sac filled with food and water.
4. The embryo-sac is composed of gametophyte cells.
5. The majority of flowering plants have an embryo sac consisting of seven cells and eight nuclei.
6. They are one egg (female gamete), two synergids, one central cell (secondary nucleus) and three antipodals.
7. Central cell contains two nuclei, they are called polar nuclei.

Question 25.
Prepare a flow chart to explain the process of sexual reproduction in plants
Answer:

Question 26.
Draw a neat labelled diagram to explain plant fertilisation. Write few points on Pollen grain.
Answer:

Pollen grains:

1. Pollen grains develop in anther.
2. Anther consists of spore-forming tissue. Some of the cells in the spore-forming tissue develop as pollen mother cells.
3. Each pollen mother cell undergoes meiosis to form four daughter cells which develop into pollen grains
4. Pollen grains are haploid (‘n’) and are otherwise known as microspores or male gametes.
5. They contain only one set of chromosomes (‘n’).
6. The study of pollen grain is called palynology.
7. During pollination pollen grains are dispersed by wind and insects.
8. Pollen grains are formed in large numbers. They are light in weight and are easily carried by wind currents.

Question 27.
How will you appreciate cell division that helps in perpetuation of life?
Answer:

1. Perpetuation means continuation of life.
2. The perpetuation of life is based on the cell division.
3. Both mitotic and meiotic divisions are very essential for perpetuation of life.
4. In unicellular organisms, the mitotic cell divisions form the entire organisms.
5. Mitotic division is essential for all types of asexual reproductions.
6. In sexually reproducing organisms meiotic cell division helps in formation of gametes with haploid number of chromosomes which fuses to form diploid zygote during fertilization.
7. Zygote further divides by mitosis again and grows into an embryo and then to offspring.
8. Thus both mitotic and meiotic cell divisions play a key role in perpetuation of life. Without cell division, there is no perpetuation of life.

Question 28.
What precautions will you take to keep away from various sexually transmitted?
Answer:
Precautions to be taken to keep away from various sexually transmitted diseases:

1. Avoid sex with any one who has genital sores, a rash, discharge or other symptoms.
2. The only time unprotected sex is a safe if the partners have sex only with each other.
3. I use latex condoms every time 1 participate in sex. I use it for the entire sex act.
4. I avoid sharing towels or under clothing.
5. I wash genital organ before and after intercourse.
6. I will get a vaccination for hepatitis B. This is a series of three shots.
7. I will get tested for HIV for every six months.
8. I will not drunk or take drugs. Under these conditions, I may fail to have safe sex.
9. I consider that not having sex is the only way, sure way to prevent sexually transmitted diseases.
10. Sexual act is supposed to be an act between husband and wife. Hence I will not participate in sex before marriage.
11. When I grow up and get married, I will be upright and faithful to the life partner and will not behave immorally.
12. Hence as a student I will concentrate on studies and create activities to achieve success in life.

Question 29.
Conduct a seminar on child marriages and foeticide.
Answer:
child marriages can also be defined as “any marriage carried out under the age of 18 years and involves the girl who is physically, psychologically, mentally and physiologically immature”.

Causes of Child marriages :

1. Poverty in the families due to unemployment.
2. Illiteracy among people.
3. Ignorance of consequences of child marriages.
4. Strong superstitions among people about child marriages.
5. Religious and traditions are also responsible for occurance of child marriages.

Steps to prevent Child marriages:

1. By creating awareness among the people about the ill effects of child marriages.
2. By educating the people especially in rural areas of backward districts.
3. By providing employment opportunities to all the people.
4. Performing live plays, skits and stage shows to create enlightenment among the rural illiterate women about the pathetic future of kids who are forced to get married.

Foeticide:

1. Foeticide is the illegal practice of killing a foetus. Female foeticide is prevalent in our country as a major social evil.
2. Some kinds of complications in pregnancy can also demand surgical termination of pregnancy after 8 weeks of conception.
3. This is where the abortion is legal and doctors may have to suggest for discontinuous of pregnancy for the sake of health of the mother. However the technique of surgical termination is misused by some people by getting rid of the unborn child.
4. Abortion of foetus is an act of murder. God is the author of life and nobody should have right to take it.

Choose the correct answer.

1. The part of the female reproductive system produces the eggs [ ]
A) Ovary
B) Epididymis
C) Cervix
D) Fallopian tube
Answer: A

2. The term that we use to describe a sperm cell fusing with an egg cell [ ]
A) Fragmentation
B) Fermentation
C) Fertilisation
D) Fusion
Answer: C

3. Which part of the male reproductive system produces (human) the sperm cells ? [ ]
A) Vas deference
B) Epididymis
C) Seminiferous tubules
D) Scrotum
Answer: C

4. How does the sperm break through the egg cell membrane? Choose the option you think is right.   [ ]
A) Tears a hole in the membrane
B) Dissolves the membrane with chemicals
C) Bites through the membrane with teeth
D) Squeezes through gaps in the membrane
Answer: B

5. Why are egg cells larger than sperm cells? Choose the option you think is right. [ ]
A) Egg cells have more cells in them
B) Have food store to help growth after fertilisation
C) Have thicker cell membranes
D) Have larger nuclei
Answer: B

6. Which of these things will affect the way a foetus grows? Choose the option you think is right. [ ]
A) Chemicals in cigarette smoke
B) Alcohol
C) Drugs
D) All of the above
Answer: D

7. Which of the following is the correct sequence of steps in the human life cycle? Choose the right option. [ ]
A) Babyhood, childhood, adolescence, adulthood
B) Childhood, babyhood, adulthood, adolescence
C) Adolescence, babyhood, adulthood, childhood
D) None of the above
Answer: A