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Secondary 3 Biology Cells Biomolecules Quiz
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Questions
Secondary 3 Biology Quiz - Cells Biomolecules
Name: _________________________ Class: _________________________ Date: _________________________ Score: ______ / 40
Duration: 45 minutes Total Marks: 40
Instructions:
- This quiz contains 20 questions on Cells and Biomolecules.
- Answer ALL questions in the spaces provided.
- The number of marks is shown in brackets [ ] at the end of each question or part question.
- Where diagrams are referenced, use the information provided to answer the questions.
Section A: Multiple Choice (5 marks)
Choose the most appropriate answer for each question. Write the letter (A, B, C, or D) in the box provided.
1. An actively growing cell is supplied with radioactive amino acids. Which cell component would first show an increase in radioactivity?
A. Golgi body B. Mitochondria C. Nucleus D. Rough endoplasmic reticulum
[ ] [1]
2. In the pancreas, there are groups of cells that produce insulin. Which term best describes these cells?
A. An organ in an organism B. An organ system in an organism C. A tissue in an organ D. Cells within a cell wall
[ ] [1]
3. Which of the following correctly pairs a cell structure with its function?
A. Mitochondria – protein synthesis B. Ribosomes – energy production C. Golgi body – modification and packaging of proteins D. Nucleus – lipid synthesis
[ ] [1]
4. A student observes a cell under a microscope and notes the presence of a cell wall, chloroplasts, and a large central vacuole. This cell is most likely from:
A. A human cheek B. A plant leaf C. A human muscle D. An animal liver
[ ] [1]
5. Which statement about enzymes is correct?
A. Enzymes are used up during the reaction. B. Enzymes can catalyse many different types of reactions. C. Enzymes lower the activation energy of a reaction. D. Enzymes work best at very high temperatures.
[ ] [1]
Section B: Short Answer (10 marks)
Answer the following questions in the spaces provided.
6. State two differences between a typical plant cell and a typical animal cell.
[2]
(a) ________________________________________________________________________
(b) ________________________________________________________________________
7. The diagram below shows an animal cell with numbered labels.
[Diagram: Animal cell with labels 1-6 pointing to:
1 - Nucleus
2 - Rough endoplasmic reticulum
3 - Mitochondrion
4 - Golgi body
5 - Secretory vesicle
6 - Cell membrane]
(a) Which numbered structure is involved in the modification and export of proteins?
[1]
Answer: __________
(b) State the function of structure 3.
[1]
8. Explain why red blood cells do not have a nucleus. Relate your answer to the function of red blood cells.
[2]
9. Define the term osmosis.
[2]
10. State two factors that affect the rate of enzyme activity.
[2]
(a) ________________________________________________________________________
(b) ________________________________________________________________________
Section C: Structured Response (15 marks)
Answer the following questions in the spaces provided. The number of marks indicates the depth of response required.
11. The diagram below shows four different types of cells found in a mammalian body.
[Diagram: Cell P - nerve cell with long axon; Cell Q - red blood cell (biconcave);
Cell R - sperm cell with flagellum; Cell S - epithelial cell with microvilli]
(a) Identify which cell (P, Q, R, or S) is best adapted for rapid transmission of signals. Explain your choice.
[2]
Cell: __________
Explanation: ________________________________________________________________
(b) Identify which cell (P, Q, R, or S) is best adapted for absorption of nutrients. Explain your choice.
[2]
Cell: __________
Explanation: ________________________________________________________________
12. A student carried out an investigation using the apparatus shown below.
[Diagram: Visking tubing containing starch solution and amylase, suspended in a beaker of water]
The Visking tubing is permeable to water and small molecules but not to starch. The student tested the water in the beaker after 30 minutes.
(a) Name the substance that would be found in the water after 30 minutes. Explain your answer.
[2]
(b) Explain why starch would not be found in the water outside the Visking tubing.
[2]
13. Describe and explain how a root hair cell is adapted to its function of absorbing water and mineral ions from the soil.
[4]
14. An enzyme extracted from the stomach works best at pH 2. Explain what would happen to the activity of this enzyme if it were placed in a solution of pH 8.
[3]
15. Compare the structure and function of mitochondria and chloroplasts.
[3]
Section D: Data-Based Question (10 marks)
Study the following information and answer the questions that follow.
16. An investigation was carried out to study the effect of temperature on the activity of enzyme X. The results are shown in the table below.
| Temperature (°C) | Rate of reaction (arbitrary units) |
|---|---|
| 10 | 12 |
| 20 | 28 |
| 30 | 45 |
| 40 | 48 |
| 50 | 30 |
| 60 | 5 |
(a) Plot a graph of the results on the grid below. Label both axes clearly.
[4]
[Grid provided for graph plotting]
(b) Describe the effect of temperature on the rate of reaction between 10°C and 40°C.
[2]
(c) Explain why the rate of reaction decreases sharply between 50°C and 60°C.
[2]
(d) State the optimum temperature for enzyme X.
[1]
(e) Predict the rate of reaction at 70°C. Explain your prediction.
[1]
17. The diagram below shows the fluid mosaic model of the cell membrane.
[Diagram: Cell membrane with labeled parts: phospholipid bilayer, protein channel, glycoprotein]
(a) Identify the molecule labeled A (pointing to a phospholipid).
[1]
(b) State one function of the protein channel labeled B.
[1]
18. A student placed a piece of potato in a concentrated sugar solution. After 30 minutes, the potato became soft and flaccid. Explain this observation.
[2]
19. Explain why a plant cell does not burst when placed in a hypotonic solution, whereas an animal cell does.
[2]
20. Describe the lock-and-key hypothesis of enzyme action.
[2]
END OF QUIZ
Answers
Secondary 3 Biology Quiz - Cells Biomolecules - ANSWER KEY
Total Marks: 40
Section A: Multiple Choice (5 marks)
1. D - Rough endoplasmic reticulum [1] Radioactive amino acids are incorporated into proteins at ribosomes on the RER. The RER is the first organelle in the protein synthesis pathway.
2. C - A tissue in an organ [1] A group of similar cells performing the same function (producing insulin) is a tissue. The pancreas is the organ.
3. C - Golgi body – modification and packaging of proteins [1] Golgi body modifies proteins and packages them into vesicles for secretion.
4. B - A plant leaf [1] Cell wall, chloroplasts, and large central vacuole are characteristic of plant cells.
5. C - Enzymes lower the activation energy of a reaction [1] Enzymes are biological catalysts that lower activation energy; they are not used up, are specific, and denature at high temperatures.
Section B: Short Answer (10 marks)
6. Any two differences: [2]
- Plant cell has a cell wall; animal cell does not.
- Plant cell has chloroplasts; animal cell does not.
- Plant cell has a large central vacuole; animal cell has small, temporary vacuoles (if present).
- Plant cell has a fixed/regular shape; animal cell has an irregular shape. (Award 1 mark each for any two correct differences.)
7. (a) Structure 4 (Golgi body) [1] (b) Structure 3 (mitochondrion) is the site of aerobic respiration / produces energy (ATP) for the cell. [1]
8. Red blood cells do not have a nucleus to provide more space for haemoglobin [1], which enables them to carry more oxygen for transport around the body [1].
9. Osmosis is the net movement of water molecules [1] from a region of higher water potential to a region of lower water potential through a partially permeable membrane [1].
10. Any two factors: [2]
- Temperature
- pH
- Substrate concentration
- Enzyme concentration (Award 1 mark each for any two correct factors.)
Section C: Structured Response (15 marks)
11. (a) Cell: P (nerve cell) [1] Explanation: The nerve cell has a long axon which allows rapid transmission of electrical impulses/signals over long distances [1].
(b) Cell: S (epithelial cell) [1] Explanation: The epithelial cell has microvilli which increase the surface area for absorption of nutrients [1].
12. (a) Reducing sugars / maltose / glucose [1] Explanation: Amylase breaks down starch into reducing sugars (maltose). These are small molecules that can pass through the Visking tubing into the surrounding water [1].
(b) Starch molecules are too large to pass through the pores of the Visking tubing [1]. The Visking tubing acts as a partially permeable membrane that only allows small molecules to pass through [1].
13. Root hair cell adaptations (award up to 4 marks):
- Long, narrow extension/projection – increases surface area for absorption of water and mineral ions [1]
- Thin cell wall – reduces the diffusion distance for water and mineral ions [1]
- Large number of mitochondria – provides energy (ATP) for active transport of mineral ions against the concentration gradient [1]
- Cell membrane contains carrier proteins – for active transport of mineral ions [1]
- No chloroplasts – as root hair cells are underground and do not photosynthesise [1] (Award 1 mark for each correct adaptation with explanation, up to 4 marks.)
14. At pH 8, the enzyme would have very low or no activity / would be denatured [1]. Explanation: The enzyme extracted from the stomach works best at pH 2 (acidic conditions). At pH 8 (alkaline conditions), the shape of the active site changes [1], so the substrate can no longer fit into the active site (lock-and-key model disrupted). The enzyme is denatured [1].
15. Mitochondria and chloroplasts comparison: [3]
- Mitochondria are the site of aerobic respiration; chloroplasts are the site of photosynthesis [1].
- Both have a double membrane [1].
- Mitochondria have cristae (folded inner membrane); chloroplasts have thylakoids/grana [1]. (Award 1 mark for each correct point of comparison, up to 3 marks.)
Section D: Data-Based Question (10 marks)
16. (a) Graph: [4]
- Correct axes labels: x-axis "Temperature (°C)", y-axis "Rate of reaction (arbitrary units)" [1]
- Appropriate scales on both axes [1]
- All 6 points plotted accurately [1]
- Points joined with a smooth curve (not straight lines) [1]
(b) As temperature increases from 10°C to 40°C, the rate of reaction increases [1]. This is because the enzyme and substrate molecules have more kinetic energy, so they move faster and collide more frequently, increasing the chance of successful enzyme-substrate complex formation [1].
(c) Between 50°C and 60°C, the rate of reaction decreases sharply because the enzyme is denatured [1]. The high temperature breaks the bonds that maintain the three-dimensional shape of the enzyme, changing the shape of the active site so the substrate can no longer bind [1].
(d) 40°C [1]
(e) The rate of reaction at 70°C would be 0 (or close to 0) [1] because the enzyme would be completely denatured and unable to catalyse the reaction.
17. (a) Phospholipid / phospholipid molecule [1] (b) The protein channel allows specific molecules/ions to pass through the membrane / facilitates diffusion of substances across the membrane [1].
18. The concentrated sugar solution has a lower water potential than the potato cells [1]. Water moves out of the potato cells by osmosis, causing the cells to become plasmolysed/flaccid, so the potato becomes soft [1].
19. A plant cell has a strong, rigid cell wall that prevents it from bursting [1]. An animal cell lacks a cell wall, so in a hypotonic solution, water enters by osmosis and the cell swells and may burst (lyse) [1].
20. The lock-and-key hypothesis states that the active site of an enzyme has a specific shape that is complementary to the shape of the substrate [1]. The substrate fits into the active site like a key fits into a lock, forming an enzyme-substrate complex, and the reaction takes place [1].
END OF ANSWER KEY