AP State Syllabus AP Board 9th Class Biology Important Questions Chapter 1 Cell its Structure and Functions.
AP State Syllabus 9th Class Biology Important Questions 1st Lesson Cell its Structure and Functions
9th Class Biology 1st Lesson Cell its Structure and Functions 1 Mark Important Questions and Answers
What are the cell organelles present in a cell?
The cell organelles present in a cell are endoplasmic reticulum, golgi apparatus, lysosomes, mitochondria, ribosomes, plastids and vacuoles.
What is the role played by cell wall in plant cells?
- Cell wall excretes and inward wall pressure to resists the outward directed pres¬sure exerted by cell sap.
- So, the plant cells can withstand much greater changes in surrounding medium than animal cells.
What is cell theory?
- Cell theory was proposed by Schleiden and Schwann.
- All living organisms are composed of cells and product of cell.
- All cells arise from pre-existing cells.
Write one precaution while observing nucleus in cheek cells.
- Do not scrap the cheek too hard as it may injure the buccal mucosa.
- Excess stain should be drained off.
Name the colourless plastids in plants.
Write the name of the plastids that are responsible for different colours in flowers and fruits.
Mention the cell organell that is called “Protein factories”.
Name the cell organell that is known as “suicidal bags of the cell”.
Write the main function of Smooth Endoplasmic Reticulum.
The SER helps in the manufacture of fat molecules or lipids important for cell function.
What happens if Endoplasmic reticulum is destroyed in the cell?
The transportation of substances from one part to another part of the cell will not occur.
What is the site of protein synthesis in the cell?
Write some examples for prokaryotic cells.
Bacterium, Cyanobacteria and Blue green algae are examples for prokaryotic cells.
Write the unique feature seen in plant cells.
Presence of cell wall is the unique feature seen in plant cells.
Name the selectively permeable membrane that covers the cell.
What is an enzyme?
An organic catalyst which catalyses a reaction within a cell.
Who coined the term ’Cytoblast’ and why?
Schleiden called the nucleus as cytoblast, because he thought that new cells were created from the nucleus.
What is the site of cellular respiration?
What are vacuoles and write their function.
Vacuoles are the fluid filled sac like structures present in the cytoplasm. They store solid or liquid contents.
9th Class Biology 1st Lesson Cell its Structure and Functions 2 Marks Important Questions and Answers
What is the difference between protoplasm and cytoplasm?
- There is a fluid present inside the cell.
- For a long time it was believed that the essence of life was stored in the fluid.
- Hence the fluid was named as protoplasm, which means life fluid.
- When it became clear that the fluid is basically a medium in which various particles and membranes float, protoplasm was renamed as cytoplasm.
Take one grape fruit and place it in salt solution, Note the observations.
- I take one grape fruit and placed it in salt solution.
- After sometime I observed that the fruit shrunk.
- This is because of loss of water inside the fruit, it comes out into salt solution.
- During this, the process of osmosis takes place.
Collect some parts of plants like, orange, beetroot, raddish, drumsticks, lady’s fin-ger, Jasmine, etc. and put a tick mark if you find the listed plastids present in them.
Why animals depend upon plants for food?
- Animal cells do not have chloroplasts.
- Chloroplast trap the energy from sunlight.
- It converts solar energy to chemical energy which takes place during photosynthesis.
- During the process of photosynthesis food materials are formed.
- Due to lack of chloroplasts animals are unable to prepare their own food.
- So, animals depend on plants for food.
|Nucleus||Nucleus regulates and controls all the functions of a cell and determines the characteristics of the organism.|
|Endoplasmic reticulum||1. It serve as channels for the transport of materials within the cell.|
|2. It also functions as a cytoplasmic framework for various biochemical activities.|
|Golgi Apparatus||It package various substances. Proteins are altered slightly by golgi apparatus.|
|Lysosomes||It participates in intracellular digestion. It destroys the cell contents.|
|Mitochondria||It produces energy through cellular respiration.|
|Plastids||These are responsible for the colour of the plant cell.|
|A. Chloroplasts||These trap solar energy and convert this to chemical energy during photosynthesis.|
|B. Chromoplasts||These are responsible for the coloured fruits, flowers.|
|C. Leucoplasts||These are colourless, stores carbohydrates, oils and proteins.|
Study the table and answer the questions.
1) Name the cell structure that helps in photosynthesis.
2) Name the cell organell that participates in intercellular digestion.
What happens if stomata are closed with paraffin wax?
- Stomata helps in exchange of gases in leaf.
- If the stomata are closed with paraffin wax gaseous exchange will not takes place.
What questions do you pose to know more details about plasma membrane?
- How can you say that plasma membrane is also known as selectively permeable membrane?
- Name the substances that can pass through the plasma membrane.
- Give examples for selectively permeable membrane.
Write the main function of the cell wall.
- The cell wall is tough but flexible porous layer that gives a definite shape to the cell.
- It provides protection to the cell from the external shocks.
Venu is asking his teacher about different functions of cell organells of Eukaryotic cell. What questions he would ask to his teacher ?
- Prokaryotic cells devoid of nucleus . Why?
- Are the cell organells of same size in all the higher animals?
- Why lysosomes are called suicidal bags of the cell?
- What happens if cell wall is not present in plant cell?
Write about plastids.
- Plastids are present only in plant cells.
- Plastids mainly of two types. 1. Chromoplasts (coloured) and leucoplasts (colourless).
- Chloroplasts are the type of chromoplasts present only in plants.
- The primary function of a chloroplast is to trap the energy of sunlight and transform it to chemical energy thus helping to carryout photosynthesis.
- Chromoplasts are responsible for having various colours of fruits, flowers and leaves.
- Leucoplasts are used to store starch, oil and proteins.
Write differences between plasma membrane and cell wall.
|Plasma membrane||Cell wall|
|1. Made up of lipid and proteins.||1. Made up of cellulose.|
|2. It is Living.||2. It is Dead.|
|3. Present in both plant and animal cell.||3. Found exclusively in plant cells.|
What is the reason for colour change in tomatoes? (green – white – yellow – red)
1) Plastids are responsible for colour change in tomatoes.
2) Plastids are of three types :
1. Chromoplasts (coloured)
2. Leucoplasts (colourless)
3. Chloroplasts (green)
3) All the three plastids have the capacity to change from one to another.
4) As the young tomatoes mature we see green, white, yellow and red coloured tomatoes.
Draw a neat and labelled diagram of nucleus.
Draw a neat and labelled diagram showing L.S of mitochondria.
Draw a neat and labelled diagram showing the structure of chloroplast.
Draw a neat and labelled diagram of Endoplasmic Reticulum find in electron microscope.
What is the function of a nucleus in a cell?
- The nucleus plays a vital role in the cell.
- It controls all functions of the cell. It controls cell division.
- Nucleus contains chromosomes. These chromosomes contain DNA and proteins.
“Cell is the structural and functional unit of life” – How?
a) A cell is capable of independently carrying out all necessary activities of life,
b) Hence, it is called the structural and functional unit of life.
What is Protoplasm? Who coined this term and when?
a) The living fluid substance of the cell is called “Protoplasm”
b) Purkinje in 1839 coined the term protoplasm.
Name the smallest and largest known cells in this world?
a) The smallest known cells is pneumonea cell. It is about 0.1 m in diameter.
b) An Ostrich egg cell is the largest known cell. It is 170 x 135 mm approximately.
What will happen to the size of the cell if it is placed in such solutions which vary in their concentrations.
a) When placed in Hypotonic solution?
b) When placed in Isotonic solution?
- When a cell is placed in Hypotonic solution (dilute solution), water enters into the cell. Hence the cell swells up.
- When a cell is placed in Isotonic solution (same concentration), there is no movement of water. Hence the cell will stay the same size.
“A cell is a building unit of an organism”. Do you agree with this statement? If yes, explain why.
- I agree with the above statement.
- A cell is a building unit of an organism because it is responsible for building the entire body of an organism.
What is Osmosis?
Osmosis is the passage of water or any solvent from a region of its lower concentration to a higher concentration through a semi permeable membrane.
What are genes? What is their function?
Genes are the segments of DNA present on the chromosomes. These are the hereditary units which are transmitted from one generation to another by chromosomes.
9th Class Biology 1st Lesson Cell its Structure and Functions 4 Marks Important Questions and Answers
Write a short note on the Golgi apparatus.
- Camillo Golgi first observed the golgi bodies in 1898.
- This is made up of several membranes.
- These membranes create sac-like structure around which many fluid-filled vesicles abound.
- The proteins and other substances produced in the ribosomes reaches the golgi body through these vesicles.
- This organelle package various substances before Ciste they are transported to other parts of the cell. _
- The number of golgi bodies varies from cell to cell. Golgi apparatus
- They are large in number in those cells that secrete hormones and enzymes.
Write about mitochondria.
- Mitochondria are small, spherical or cylindrical in shape.
- They are 2-8 micron long and about 0.5 micron wide.
- It is about 150 times smaller than the nucleus.
- 100 – 150 are present in each cell.
- They are made of a double-membrane
- The inner membrane of the wall protrudes into the interior in folds and forms cristae.
- The space between cristae is known as the matrix.
- They are responsible for cellular respiration.
- Energy generated and stored in mitochondria.
- Hence they are also called as cell’s power house.
Write a note on Cytoskeleton.
- Endoplasmic Reticulum (ER) is one of the important cell organelle.
- It extends all over the cell, so it is also called as cytoskeleton.
- It is responsible for the transport of substances from one part of the cell to another.
- RER has ribosomes on its surface which are caused for protein manufacture.
- The SER helps in the manufacture of fat molecules.
- Invertebrate liver cells SER plays a crucial role in detoxifying many poisons and drugs.
How could you appreaciate the function of nucleus in a cell?
- Nucleus is the most prominent one of all cell organelles.
- This is also known as cell’s control room.
- It was named by Robert Brown in 1831.
- All cells have nucleus except a few cells.
- In mammal red blood cells and phloem sieve tube in plants nucleus is absent.
- It regulates and controls all the functions of the cell.
- It determines the characteristics of the organism.
- It is the barrier of all genetic information.
- It involved in the process of cell division.
- If there is no nucleus in the cell, growth of organism not takes place.
Draw the diagram of nucleus and label it.
Why the colouring fruits or vegetables changes? Support your answer.
- In plants plastids are responsible for the colouring of fruits and vegetables.
- There are 3 types of plastids present in plants.
- Chloroplasts are responsible for green colour.
- Chromoplasts are responsible for different colours, i.e., orange, yellow, red etc.
- Leucoplasts are responsible for white colour.
- These plastids have the capacity to change from one form to another.
- E.g. : Young tomatoes are white in colour as they mature they turn to green and then to red in colour.
In what way different colours in flowers helpful to bio-diversity?
- We can easily identify their species at a glance.
- By having different colours plants attracts insects for pollination, for their propagation.
- By having different colours plants appeal to the aesthetic sense of man, immense pleasure and happiness.
- This is useful in the propagation of plants by the human beings.
- Generally butterflies are known as the pollinators, but in fact they are the indicators of the health of an ecosystem.
Describe endoplasmic reticulum.
- The network or membranes present in the cytoplasm for the transport of substances
from the one part of the cell to another is known as endoplasmic reticulum.
- Endoplasmic reticulum is of two types.
i) Rough endoplasmic reticulum and
ii) Smooth endoplasmic reticulum.
- Endoplasmic reticulum having ribosomes on their surface is known as rough endoplasmic reticulum.
- The rough endoplasmic reticulum is the sites of protein synthesis.
- Ribosomes are absent in smooth endoplasmic reticulum and is involved in lipid synthesis.
- One function of the endoplasmic reticulum is to serve as channels for the transport of materials within the cytoplasm.
- It also function as a cytoplasmic framework providing a surface for some of the biochemical activities of the cell.
Observe the following slides under the microscope and draw their pictures. Write the cell organelles in them.
Organelles present in Amoeba :
Nucleus, contractile vacuole, food vacuole etc.
Organelles present in Euglena :
Nucleus, chloroplasts, contractile vacuole, reservoir, paraflagellar body, endosome etc.
Cell organelles present in Paramoecium :
Anterior and posterior contractile vacuoles, micronucleus, macronucleus, cytostome, cytopyge, food vacuole etc.
Collect the names and photographs of scientists helped for the development of cell biology. Give brief note on them.
- 1632 – 1723 Antonie Van Leeuwenhoek constructed simple microscope and draws protozoa, verticella from rain water and bacterium from his mouth.
- 1665 Robert Hooke discover cells in Cork, then in living plant tissues using an early compound microscope.
- In 1831 Robert Brown discovered nucleus. In 1839 Purkinje coined the term protoplasm.
- In 1839 Theodar Schwann and M.J. Schleiden proposed cell theory.
- 1855 – Rudolf Carl Virchow observed cell division.
- 1931 – Earnest Ruska built first transmission electron microscope.
- 1953 – Watson & Crick made their first announcement on the double helix structure of DNA.
- Albert Claude, father of cell biology awarded Nobel prize for Physiology (Medicine) in 1974.
- 1981 – Lynn Margulis published symbiosis in cell evolution detailing the endosymbiotic theory.
9th Class Biology 1st Lesson Cell its Structure and Functions Important Questions and Answers
What happens if there are no mitochondria in eukaryotic cell?
If Mitochondria are absent in Eukaryotes, the energy required to perform all cellular activities will not be released. Hence, all the biological activities occurring in the cell will be stopped ultimately. This leads to the death of the eukaryotic cell.
What are the differences between protoplasm and cytoplasm?
- Protoplasm is the content of the cell including the cell membrane, cytoplasm and the cell nucleus.
- Cytoplasm is the jelly like substance surrounding the nucleus within the cell membrane. The cytoplasm contains the cell organelles like mitochondria, ribosomes, etc.
a) Identify the figure and write the parts.
b) Write a short note on the above figure.
- Inner membrane
- Outer membrane
- The above shown cell organelle is mitochondria.
- It performs cellular respiration and releases energy required for all cellular activities.
- Mitochondria is also known as “Power house of the cell”.
- Mitochondria are made up of a double membrane wall. The inner membrane of the wall protrudes into the interior in folds and forms structures called cristae.
- The space between cristae is filled with a fluid known as the matrix.
Write the functions of the following cell organelles.
- Mitochondria performs cellular respiration. They release energy for all biological activities of the cell.
- Chloroplasts trap the solar energy and helpful in photosynthesis through which plants derive their food.
a) Draw a neat labelled diagram of a plant cell.
b) Write the functions of endoplasmic reticulum.
b) Functions of Endoplasmic Reticulum :
- The ER is to serve as channels for the transport of materials between various regions of the cytoplasm or between the cytoplasm and the nucleus.
- It is the site of many bio – chemical activities in the cell.
- It helps in the synthesis of proteins and lipids.
- In vertebrate liver cells, SER plays a crucial role in detoxifying many poisons and drugs.
What does the modern cell theory propose?
i) All living organisms are composed of cells and products of the cells.
ii) All cells arise from the pre existing cells.
What happens if lysosomes are absent in the cell?
The materials that need to be destroyed are sent to lysosomes. They release the enzymes and digest them. If lysosomes are not present, the harmful substances which are dangerous to the cell would not be destroyed. The cell may die.
Name the chemical substance used in cheek cell lab activity.
Describe the nucleus of cell with the help of a well labelled diagram.
- The membrane that encloses the nucleus and separates it from contents of cytoplasm is known as nuclear membrane.
- The entire genetic material of the cell is found in the nucleus.
- The nucleus has fluid like substance called nucleoplasm.
- In the centro of the nucleus, we can see a round shaped structure called nucleolus.
- Nucleus controls and regulates all the activities of the cell.
- Nucleus is closely involved in the process of cell division.
- Write an activity to observe the nucleus in cheek cells.
- Write a brief notes about mitochondria with help of the diagram.
- Draw the diagram of Nucleus and label its parts.
- Write name of the following figure and write its parts.
- Write the name of the following figure and write its parts.