Cell: The Unit of Life

Correct Answer: B

1. Mitochondria are small cell organelles.
2. They are present in the cytoplasm of eukaryotic cells.
3. They are difficult to see clearly under a microscope.
4. This is because they are not naturally very visible.
5. Special techniques are needed to observe them.
6. Staining helps in making them visible.
7. Dyes highlight their structure and boundaries.
8. This improves contrast under the microscope.
9. Then mitochondria can be studied clearly.
10. Thus, they are not easily visible unless stained.

Correct Answer: B

1. Mitochondria produce energy in the cell.
2. Different cells have different energy needs.
3. Cells that work more need more energy.
4. Such cells contain more mitochondria.
5. Less active cells have fewer mitochondria.
6. This depends on the activity of the cell.
7. This activity is called physiological activity.
8. It includes functions like movement and metabolism.
9. More activity means more energy demand.
10. Thus, mitochondria number depends on physiological activity.

Correct Answer: B

1. Mitochondria are not always the same in appearance.
2. They can differ in their shape.
3. Some may be round, oval or elongated.
4. Their size can also vary from cell to cell.
5. Larger cells may have bigger mitochondria.
6. Smaller cells may have smaller ones.
7. This variation depends on cell type and function.
8. Active cells may show different forms.
9. This flexibility helps in adapting to energy needs.
10. Thus, mitochondria show variability in shape and size.

Correct Answer: B

1. Mitochondria have a typical shape in cells.
2. They are usually sausage-shaped or cylindrical.
3. Their diameter is very small.
4. It ranges from 0.2 to 1.0 micrometers.
5. The average diameter is about 0.5 micrometers.
6. Their length is longer than diameter.
7. It ranges from 1.0 to 4.1 micrometers.
8. This shape helps in efficient energy production.
9. They fit well within the cytoplasm.
10. Thus, mitochondria have characteristic size and shape.

Correct Answer: B

1. Mitochondria are important energy-producing organelles.
2. Each mitochondrion has two membranes.
3. The outer membrane covers the organelle.
4. The inner membrane is folded inside.
5. These membranes create two compartments.
6. One is the outer compartment between membranes.
7. The other is the inner compartment called matrix.
8. This structure helps in efficient energy production.
9. Different reactions occur in each compartment.
10. Thus, mitochondria are double membrane-bound structures.

Correct Answer: B

1. Mitochondria have two compartments inside.
2. The inner compartment is surrounded by the inner membrane.
3. This space contains a dense material.
4. The material is uniform and gel-like.
5. It is called the matrix.
6. Matrix contains enzymes for respiration.
7. It also has mitochondrial DNA and ribosomes.
8. Many metabolic reactions occur here.
9. It plays a key role in energy production.
10. Thus, the inner compartment is filled with matrix.

Correct Answer: B

1. Mitochondria are surrounded by two membranes.
2. The outer membrane is the outermost layer.
3. It covers the entire organelle.
4. It forms a smooth boundary around mitochondria.
5. This boundary separates mitochondria from cytoplasm.
6. It is continuous and unbroken.
7. It controls movement of substances in and out.
8. It protects internal structures of mitochondria.
9. It maintains the shape of the organelle.
10. Thus, the outer membrane forms the continuous limiting boundary.

Correct Answer: B

1. The inner membrane of mitochondria is not smooth.
2. It folds inward into the inner compartment.
3. These folds are called cristae.
4. Cristae increase the surface area of the membrane.
5. More surface area helps in more energy production.
6. Important reactions of respiration occur on cristae.
7. They contain enzymes for ATP formation.
8. Cristae project towards the matrix.
9. This structure improves efficiency of the mitochondria.
10. Thus, inner membrane forms infoldings called cristae.

Correct Answer: B

1. Cristae are folds of the inner mitochondrial membrane.
2. These folds extend into the matrix.
3. They make the inner membrane highly folded.
4. Folding increases the available surface area.
5. More surface area allows more chemical reactions.
6. Important reactions of energy production occur here.
7. Enzymes for ATP synthesis are present on cristae.
8. This helps in efficient energy generation.
9. More cristae means higher energy production.
10. Thus, cristae increase the surface area.

Correct Answer: B

1. Mitochondria have two membranes: outer and inner.
2. Each membrane performs different functions.
3. Both membranes contain special molecules.
4. These molecules are called enzymes.
5. Enzymes help in chemical reactions.
6. Different enzymes are present on each membrane.
7. They support respiration and energy production.
8. Inner membrane enzymes help in ATP synthesis.
9. Outer membrane enzymes help in transport and other processes.
10. Thus, both membranes have specific enzymes for mitochondrial function.

Correct Answer: B

1. Mitochondria are known as the powerhouses of the cell.
2. They produce energy required for cellular activities.
3. This energy is generated through respiration.
4. The type of respiration occurring here needs oxygen.
5. It is called aerobic respiration.
6. During this process, food molecules are broken down.
7. Energy is released in the form of ATP.
8. This energy is used by the cell for various functions.
9. Most steps of aerobic respiration occur in mitochondria.
10. Thus, mitochondria are the sites of aerobic respiration.

Correct Answer: B

1. Mitochondria generate energy for the cell.
2. This energy is called cellular energy.
3. It is stored in the form of ATP.
4. ATP is the energy currency of the cell.
5. Cells use ATP for all activities.
6. Energy is produced during respiration.
7. Mitochondria perform this function efficiently.
8. Due to this role, they are very important organelles.
9. Hence they are called the power houses of the cell.
10. Thus, mitochondria produce cellular energy in the form of ATP.

Correct Answer: B

1. The mitochondrial matrix is the inner space of mitochondria.
2. It contains genetic material in the form of DNA.
3. This DNA is single and circular in shape.
4. It also contains RNA molecules.
5. Ribosomes present here are of 70S type.
6. These ribosomes help in protein synthesis.
7. Necessary enzymes and factors are also present.
8. This allows mitochondria to make some of its own proteins.
9. Hence, mitochondria are partly self-controlled organelles.
10. Thus, matrix contains DNA, RNA, ribosomes and protein synthesis components.

Correct Answer: B

1. Mitochondria can increase in number inside the cell.
2. They do not form from scratch each time.
3. Instead, existing mitochondria divide.
4. This division process is simple and direct.
5. It is called fission.
6. In fission, one mitochondrion splits into two.
7. Each new mitochondrion grows and functions independently.
8. This process helps maintain energy supply.
9. It is similar to bacterial cell division.
10. Thus, mitochondria divide by fission.

Correct Answer: B

1. Plastids are important cell organelles.
2. They are mainly present in plant cells.
3. They are also found in some protists.
4. Euglenoides are one such group of protists.
5. Plastids help in making and storing food.
6. Some plastids perform photosynthesis.
7. They contain pigments like chlorophyll.
8. This helps in capturing sunlight.
9. Animal cells do not have plastids.
10. Thus, plastids are found in plant cells and euglenoides.

Correct Answer: B

1. Plastids are cell organelles found in plant cells.
2. They are comparatively large in size.
3. Because of their size, they are easy to see.
4. Even a light microscope can show them clearly.
5. They often contain pigments like chlorophyll.
6. These pigments give them color.
7. This makes them more visible under microscope.
8. They are larger than many other organelles.
9. Hence, they can be easily identified.
10. Thus, plastids are easily observed because they are large.

Correct Answer: B

1. Plastids contain special pigments inside them.
2. These pigments can absorb and reflect light.
3. Different pigments show different colours.
4. For example, chlorophyll gives green colour.
5. Carotenoids give yellow or orange colour.
6. These colours are visible in leaves and fruits.
7. Pigments help in processes like photosynthesis.
8. They also make plants attractive.
9. This helps in pollination and seed dispersal.
10. Thus, plastids impart specific colours to plants.

Correct Answer: B

1. Plastids are classified based on pigments present in them.
2. Different pigments give different colours and functions.
3. Chloroplasts contain green pigment chlorophyll.
4. They help in photosynthesis.
5. Chromoplasts contain coloured pigments like carotenoids.
6. They give yellow, orange or red colours.
7. Leucoplasts are colourless plastids.
8. They mainly store food materials like starch, oils and proteins.
9. Each type has a specific role in the cell.
10. Thus, plastids are classified into chloroplasts, chromoplasts and leucoplasts.

Correct Answer: B

1. Chloroplasts are green plastids in plant cells.
2. They contain special pigments for photosynthesis.
3. The main pigment is chlorophyll.
4. It gives green colour to plants.
5. Another pigment present is carotenoid.
6. These pigments absorb light energy.
7. Light energy is used to make food.
8. This process is called photosynthesis.
9. Without these pigments, plants cannot prepare food.
10. Thus, chloroplasts contain chlorophyll and carotenoid pigments.

Correct Answer: B

1. Chromoplasts are coloured plastids found in plants.
2. They contain pigments other than chlorophyll.
3. These pigments are fat soluble.
4. They are called carotenoid pigments.
5. Examples include carotene and xanthophylls.
6. These pigments give yellow, orange or red colours.
7. They are seen in fruits and flowers.
8. They help attract pollinators and animals.
9. This supports reproduction and seed dispersal.
10. Thus, chromoplasts contain carotenoid pigments like carotene and xanthophylls.

Correct Answer: B

1. Chromoplasts contain special pigments.
2. These pigments are called carotenoids.
3. They include carotene and xanthophylls.
4. These pigments are fat soluble.
5. They reflect specific wavelengths of light.
6. This produces bright colours in plants.
7. Common colours are yellow, orange and red.
8. These colours are seen in fruits and flowers.
9. They help attract animals and insects.
10. Thus, they give plant parts yellow, orange or red colour.

Correct Answer: B

1. Leucoplasts are plastids found in plant cells.
2. They do not contain pigments, so they are colourless.
3. They occur in different shapes and sizes.
4. Their main function is storage of nutrients.
5. They are commonly found in roots and seeds.
6. There are different types based on storage function.
7. Amyloplasts are one type of leucoplast.
8. They store carbohydrates in the form of starch.
9. This starch acts as a food reserve for the plant.
10. Thus, leucoplasts are colourless plastids storing nutrients like starch.

Correct Answer: B

1. Amyloplasts are a type of leucoplast.
2. They are found in plant storage tissues.
3. Their main function is to store carbohydrates.
4. These carbohydrates are stored as starch.
5. Starch acts as a food reserve for plants.
6. It is used when energy is needed.
7. Amyloplasts are abundant in roots and tubers.
8. Potato is a common example.
9. Potato stores large amounts of starch.
10. Thus, amyloplasts store starch in plants like potato.

Correct Answer: B

1. Leucoplasts are colourless plastids in plant cells.
2. They mainly store different types of nutrients.
3. There are different types of leucoplasts.
4. Elaioplasts are one type.
5. Elaioplasts store oils and fats.
6. Aleuroplasts are another type.
7. Aleuroplasts store proteins.
8. These stored substances act as reserves.
9. They are used when the plant needs energy or growth.
10. Thus, elaioplasts store oils and aleuroplasts store proteins.

Correct Answer: B

1. Chloroplasts are present in plant cells.
2. They carry out photosynthesis.
3. Leaves are the main site of photosynthesis.
4. Inside leaves, special cells are present.
5. These are called mesophyll cells.
6. Mesophyll cells contain many chloroplasts.
7. This helps in maximum absorption of light.
8. More chloroplasts means more food production.
9. Hence they are concentrated in these cells.
10. Thus, most chloroplasts are found in mesophyll cells.

Correct Answer: B

1. Chloroplasts show different shapes in plant cells.
2. They are not always the same in appearance.
3. Common shapes include lens-shaped and oval.
4. They can also be spherical or discoid.
5. Sometimes they appear ribbon-like.
6. Their size also varies from cell to cell.
7. Length usually ranges from 5 to 10 micrometers.
8. Width ranges from 2 to 4 micrometers.
9. This variation helps in efficient photosynthesis.
10. Thus, chloroplasts have varied shapes and sizes.

Correct Answer: B

1. Chloroplast number differs in different cells.
2. Some cells have only one chloroplast.
3. Example is Chlamydomonas, a green alga.
4. It contains a single large chloroplast.
5. In higher plants, more chloroplasts are present.
6. Leaf cells contain many chloroplasts.
7. These cells are called mesophyll cells.
8. They may have 20 to 40 chloroplasts per cell.
9. This helps in efficient photosynthesis.
10. Thus, number varies from one in Chlamydomonas to many in mesophyll cells.

Correct Answer: B

1. Chloroplasts are important organelles in plant cells.
2. They are surrounded by membranes.
3. There are two membranes around each chloroplast.
4. One is the outer membrane.
5. The other is the inner membrane.
6. This structure is called double membrane-bound.
7. It is similar to mitochondria structure.
8. These membranes protect internal components.
9. They help in proper functioning of photosynthesis.
10. Thus, chloroplasts are double membrane-bound organelles.

Correct Answer: B

1. Chloroplasts have two membranes.
2. These are outer and inner membranes.
3. Each membrane has different properties.
4. The outer membrane is more permeable.
5. It allows many substances to pass through.
6. The inner membrane is more selective.
7. It controls movement of molecules strictly.
8. Hence it is less permeable.
9. This helps maintain internal conditions.
10. Thus, inner membrane is relatively less permeable.

Correct Answer: B

1. Chloroplasts have two membranes: outer and inner.
2. The inner membrane encloses an internal space.
3. This space is filled with a fluid substance.
4. It is called the stroma.
5. Stroma contains enzymes for photosynthesis.
6. It also has DNA, RNA and ribosomes.
7. Many reactions of photosynthesis occur here.
8. It supports synthesis of carbohydrates.
9. It is similar to matrix in mitochondria.
10. Thus, the inner space is called stroma.

Correct Answer: B

1. Inside the chloroplast, there is a fluid region called stroma.
2. Within the stroma, special membrane structures are present.
3. These are flattened sac-like structures.
4. They are called thylakoids.
5. Thylakoids contain chlorophyll pigments.
6. They are the site of light reactions of photosynthesis.
7. These sacs are organised in a specific way.
8. They help in efficient capture of light energy.
9. Thylakoids are essential for food production in plants.
10. Thus, flattened sacs in stroma are called thylakoids.

Correct Answer: B

1. Thylakoids are membrane sacs inside chloroplasts.
2. They are not arranged randomly.
3. They are stacked one above another.
4. This arrangement looks like a pile of coins.
5. These stacks are called grana.
6. A single stack is called a granum.
7. Grana increase the surface area for reactions.
8. They help in efficient photosynthesis.
9. Thylakoids may also connect as intergranal lamellae.
10. Thus, stacked thylakoids are called grana.

Correct Answer: B

1. Chloroplast contains stacks of thylakoids called grana.
2. These grana are not isolated from each other.
3. They are connected by membranous structures.
4. These structures are flat tubules.
5. They are called stroma lamellae.
6. They connect thylakoids of different grana.
7. This connection helps in coordination of activities.
8. It allows movement of materials between grana.
9. It supports efficient photosynthesis.
10. Thus, connecting tubules are called stroma lamellae.

Correct Answer: C

1. Thylakoids are membrane-bound sacs inside chloroplasts.
2. Each thylakoid has an internal space.
3. This space is enclosed by the thylakoid membrane.
4. The enclosed space has a specific name.
5. It is called the lumen.
6. Lumen plays a role in photosynthesis reactions.
7. It helps in maintaining proton gradient.
8. This is important for ATP formation.
9. It supports energy conversion processes.
10. Thus, the space inside thylakoid is called lumen.

Correct Answer: B

1. Stroma is the fluid part of the chloroplast.
2. It lies inside the inner membrane.
3. It contains many important substances.
4. One of them is enzymes.
5. Enzymes help in chemical reactions.
6. They are needed for making carbohydrates.
7. They also help in protein synthesis.
8. These reactions are part of photosynthesis.
9. Proper enzyme function ensures food production.
10. Thus, stroma contains enzymes for synthesis processes.

Correct Answer: B

1. Chloroplast stroma contains important components.
2. It has its own genetic material.
3. This DNA is double-stranded.
4. It is circular in shape.
5. It also contains ribosomes.
6. Ribosomes help in protein synthesis.
7. These proteins are needed for chloroplast function.
8. This shows partial independence of chloroplast.
9. Similar features are seen in mitochondria.
10. Thus, it contains circular DNA molecules and ribosomes.

Correct Answer: B

1. Chlorophyll is the green pigment in plants.
2. It is responsible for capturing light energy.
3. Chloroplast contains different internal structures.
4. Thylakoids are membrane sacs inside chloroplast.
5. Chlorophyll is located in thylakoid membranes.
6. These membranes help in light reactions.
7. Light energy is converted into chemical energy.
8. This is the first step of photosynthesis.
9. Efficient arrangement increases energy capture.
10. Thus, chlorophyll pigments are present in thylakoids.

Correct Answer: B

1. Ribosomes are structures that help in protein synthesis.
2. They are present in different parts of the cell.
3. Cytoplasm contains larger ribosomes.
4. These are called 80S ribosomes.
5. Chloroplasts also contain their own ribosomes.
6. These ribosomes are smaller in size.
7. They are called 70S ribosomes.
8. This is similar to ribosomes in prokaryotes.
9. It shows chloroplasts have some independence.
10. Thus, chloroplast ribosomes are 70S and cytoplasmic are 80S.