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Secondary 4 Combined Science Biology Cells Biomolecules Quiz

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Questions

Secondary 4 Combined Science Biology Quiz - Cells Biomolecules

Name: __________________________
Class: __________________________
Date: __________________________
Score: _______ / 40

Duration: 45 minutes
Total Marks: 40

Instructions:

Answer all questions.
Write your answers in the spaces provided.
The number of marks is indicated in brackets [ ] at the end of each question or part question.
Use black or blue ink. Diagrams should be drawn in pencil.

Section A: Multiple Choice & Short Answer (10 Marks)

1. Which of the following structures is found in a plant root hair cell but not in a human cheek cell?
A. Cell membrane
B. Cytoplasm
C. Nucleus
D. Cell wall
[1]

2. A student observes a cell under a microscope. The cell has a large central vacuole and chloroplasts. Which type of cell is this most likely to be?
A. Liver cell
B. Palisade mesophyll cell
C. Red blood cell
D. Root hair cell
[1]

3. State the process by which oxygen moves from the alveoli into the blood capillaries.

[1]

4. Why do red blood cells lack a nucleus?

[1]

5. The diagram below shows two solutions separated by a partially permeable membrane.

Image pending generation for this question.

Solution A: 5% glucose
Solution B: 10% glucose

In which direction will net movement of water molecules occur?
A. From A to B
B. From B to A
C. No net movement
D. Randomly in both directions equally
[1]

6. Define the term active transport.

[2]

7. Which organelle is responsible for protein synthesis in a cell?
A. Mitochondrion
B. Ribosome
C. Golgi apparatus
D. Lysosome
[1]

8. A potato cylinder is placed in distilled water for 2 hours. What happens to its mass?
A. It decreases because water leaves the cells.
B. It increases because water enters the cells.
C. It stays the same because the concentration is equal.
D. It decreases because solutes leave the cells.
[1]

9. Name the pigment found in chloroplasts that absorbs light energy.

[1]

10. Which of the following is a function of the cell membrane?
A. To provide structural support
B. To control the entry and exit of substances
C. To store genetic information
D. To produce energy
[1]

Section B: Structured Questions (20 Marks)

11. The table below shows the number of mitochondria in three different types of human cells.

Cell Type	Number of Mitochondria per Cell
Skin Cell	200
Muscle Cell	2,500
Red Blood Cell	0

(a) Explain why muscle cells have a significantly higher number of mitochondria than skin cells.

[2]

(b) Explain why red blood cells do not contain any mitochondria.

[2]

12. Fig. 12.1 shows a diagram of a leaf cross-section.

Image pending generation for this question.

(a) Describe two features of the palisade mesophyll cells that make them efficient for photosynthesis.

[2]

(b) The spongy mesophyll layer contains large air spaces. Explain the importance of these air spaces for the leaf.

[2]

13. A student investigates the effect of temperature on the activity of the enzyme amylase. The results are shown in the graph below.

Image pending generation for this question.

(a) Describe the effect of increasing temperature from 10°C to 37°C on the rate of reaction.

[2]

(b) Explain why the rate of reaction decreases rapidly after 45°C.

[3]

14. Glucose is absorbed from the small intestine into the blood. In some parts of the intestine, the concentration of glucose in the blood is higher than in the intestine lumen, yet glucose continues to be absorbed.

(a) Name the process responsible for this absorption.

[1]

(b) Explain why this process requires energy.

[2]

[1]

15. Fig. 15.1 shows an animal cell and a plant cell.

(a) Identify two structures present in the plant cell that are absent in the animal cell.

[2]

(b) State the function of the structure identified in (a)(1).

[1]

Section C: Data Interpretation & Extended Response (10 Marks)

16. An experiment was set up to demonstrate osmosis using visking tubing (a partially permeable membrane).

Set-up A: Visking tubing filled with 10% sucrose solution, placed in a beaker of distilled water.
Set-up B: Visking tubing filled with distilled water, placed in a beaker of 10% sucrose solution.

The height of the liquid level in the tubing was measured every 10 minutes for 40 minutes.

(a) Predict the change in liquid level in the tubing for Set-up A after 40 minutes.

[1]

(b) Explain your answer to (a) in terms of water potential and movement of water molecules.

[3]

(c) If the experiment in Set-up A was repeated using a tubing filled with 20% sucrose solution instead of 10%, how would the final height of the liquid column compare to the original result? Explain your answer.

[2]

17. "Mitochondria are known as the powerhouses of the cell."

Discuss this statement by explaining the role of mitochondria in cellular respiration and why this is vital for active processes such as active transport and muscle contraction.

[4]

18. Enzymes are biological catalysts.
(a) Define the term catalyst.

[1]

(b) Explain the "lock and key" hypothesis of enzyme action.

[2]

19. Compare and contrast diffusion and osmosis.
(a) State one similarity between diffusion and osmosis.

[1]

(b) State two differences between diffusion and osmosis.

[2]

20. A student places a strip of epidermis from a red onion bulb into a concentrated salt solution.
(a) Describe what happens to the cells after 10 minutes.

[2]

(b) Name the condition described in (a).

[1]

*** End of Quiz ***

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Answers

Secondary 4 Combined Science Biology Quiz - Cells Biomolecules (Answer Key)

Total Marks: 40

Section A: Multiple Choice & Short Answer

1. D
Reasoning: Plant cells have cell walls; animal cells do not. Both have membranes, cytoplasm, and nuclei. [1]

2. B
Reasoning: Chloroplasts are found in photosynthetic cells (palisade). Root hair cells do not have chloroplasts as they are underground. [1]

3. Diffusion [1]

4. To provide more space for haemoglobin / To increase surface area for oxygen transport / To make the cell flexible to squeeze through capillaries.
(Any one valid reason) [1]

5. A
Reasoning: Water moves from high water potential (low solute concentration, A) to low water potential (high solute concentration, B). [1]

6. The movement of substances/ions/molecules [1] from a region of lower concentration to a region of higher concentration (against the concentration gradient) [1], using energy (ATP). [1]
(Max 2 marks: 1 for direction, 1 for energy requirement)

7. B [1]

8. B
Reasoning: Distilled water has higher water potential than the potato cell sap. Water enters by osmosis, increasing mass. [1]

9. Chlorophyll [1]

10. B [1]

Section B: Structured Questions

11.
(a) Muscle cells require more energy (ATP) for contraction [1]. Mitochondria are the site of aerobic respiration which releases energy [1].
(b) Red blood cells transport oxygen [1]. If they had mitochondria, they would use some of the oxygen they carry for their own respiration, reducing the amount available for body tissues [1].
(Alternative: Lack of mitochondria allows more space for haemoglobin)

12.
(a) Any two from:

Located near the upper surface of the leaf to receive maximum light [1].
Packed tightly/vertically to contain many chloroplasts [1].
Contains many chloroplasts to trap light energy [1].
(b) The air spaces allow for the diffusion of gases (carbon dioxide and oxygen) [1]. This ensures a constant supply of CO₂ for photosynthesis and removal of O₂ [1].

13.
(a) The rate of reaction increases [1] because the kinetic energy of enzyme and substrate molecules increases, leading to more frequent and successful collisions [1].
(b) At high temperatures, the heat energy breaks the bonds holding the enzyme's structure [1]. The enzyme denatures [1], changing the shape of the active site so the substrate can no longer bind [1].

14.
(a) Active transport [1]
(b) Because glucose is being moved against the concentration gradient (from low to high concentration) [1]. This requires energy input to pump the molecules [1].
(c) Mitochondria [1]

15.
(a) Cell wall [1] and Chloroplast (or Large Central Vacuole) [1].
(b) Function of Cell Wall: Provides structural support and maintains cell shape / Prevents bursting due to osmotic pressure. [1]
(If Chloroplast chosen: Site of photosynthesis. If Vacuole chosen: Stores cell sap/maintains turgor pressure.)

Section C: Data Interpretation & Extended Response

16.
(a) The liquid level in the tubing will rise. [1]
(b) The distilled water in the beaker has a higher water potential than the 10% sucrose solution in the tubing [1]. Water molecules move by osmosis [1] through the partially permeable membrane [1] from the beaker into the tubing, causing the volume/level to increase. [1]
(c) The final height would be higher [1]. This is because the concentration gradient (difference in water potential) between the 20% sucrose and distilled water is steeper than with 10% sucrose, resulting in a faster rate of osmosis and more water entering the tubing. [1]

17.
Marking Guide:

Role of Mitochondria: Site of aerobic respiration [1]. Converts glucose and oxygen into energy (ATP), carbon dioxide, and water [1].
Link to Active Processes:
- Active Transport: Requires ATP to move substances against concentration gradient (e.g., uptake of minerals in roots or glucose in intestine) [1].
- Muscle Contraction: Requires ATP for myosin heads to pull actin filaments (sliding filament theory) [1].
Conclusion: Without mitochondria, cells would not produce sufficient ATP via aerobic respiration to sustain these energy-demanding processes, leading to cell death or function failure. [1]
(Award marks for logical flow and correct biological terminology. Max 4 marks.)

18.
(a) A substance that increases the rate of a chemical reaction [1] without being used up/changed in the process. [1]
(Note: Question 18 in quiz is split into a and b, but marks in quiz are 1 and 2. Total 3 marks. Wait, Quiz Q18 is 1+2=3 marks. Key must match.)
Correction for Q18 Key:
(a) A substance that speeds up a chemical reaction without being consumed. [1]
(b) The enzyme (lock) has a specific active site shape [1]. The substrate (key) has a complementary shape that fits into the active site [1], forming an enzyme-substrate complex. [1]
(Total 3 marks for Q18)

19.
(a) Both involve the movement of molecules from a region of higher concentration to a region of lower concentration (down a concentration gradient) / Both are passive processes (do not require energy). [1]
(b) Any two differences:

Osmosis involves only water molecules; diffusion involves any molecules/ions. [1]
Osmosis requires a partially permeable membrane; diffusion does not necessarily require a membrane. [1]

20.
(a) The cytoplasm shrinks/pulls away from the cell wall [1]. The vacuole becomes smaller. [1]
(b) Plasmolysis [1]