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Secondary 4 Pure Biology Practice Paper 5
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TuitionGoWhere Practice Paper - Pure Biology Secondary 4
TuitionGoWhere Practice Paper (AI)
Version: 5 of 5
Subject: Pure Biology
Level: Secondary 4 (G3/Express)
Paper: Practice Paper – Cells and Biomolecules
Duration: 1 hour
Total Marks: 50
Name: __________________________
Class: __________________________
Date: __________________________
Instructions to Candidates
- Write your name, class, and date in the spaces above.
- Answer all questions.
- Write your answers in the spaces provided on this question paper.
- The number of marks is given in brackets [ ] at the end of each question or part question.
- You may use a calculator.
Section A: Multiple Choice Questions (10 Marks)
Answer all questions. For each question, there are four options. Choose the correct one.
1. Which of the following structures is found in a typical plant cell but not in a typical animal cell?
A. Cell membrane
B. Cytoplasm
C. Mitochondrion
D. Cell wall
[1]
2. A student observes a cell under an electron microscope. The cell contains many mitochondria and extensive rough endoplasmic reticulum. What is the most likely function of this cell?
A. Storage of starch
B. Synthesis and secretion of proteins
C. Absorption of water
D. Contraction for movement
[1]
3. Which row correctly describes the movement of molecules during active transport?
| Option | Direction of Movement | Energy Requirement |
|---|---|---|
| A | High concentration to low concentration | No |
| B | Low concentration to high concentration | Yes |
| C | High concentration to low concentration | Yes |
| D | Low concentration to high concentration | No |
[1]
4. An enzyme is heated to 80°C and then cooled to 37°C. Its activity is measured. What is the result?
A. Activity increases because the enzyme is reactivated.
B. Activity remains zero because the enzyme is denatured.
C. Activity increases because the kinetic energy of molecules increases.
D. Activity remains the same as before heating.
[1]
5. Which test reagent is used to identify the presence of reducing sugars, and what is the positive result?
A. Iodine solution; blue-black colour
B. Biuret solution; purple colour
C. Benedict’s solution; brick-red precipitate
D. Ethanol; white emulsion
[1]
6. Fig. 1 shows a red blood cell placed in a solution. The cell has shrunk and become crenated.
What describes the water potential of the solution compared to the cytoplasm of the red blood cell?
A. Higher water potential
B. Lower water potential
C. Equal water potential
D. Zero water potential
[1]
7. Which molecule is a polymer made of amino acid monomers?
A. Glycogen
B. Cellulose
C. Haemoglobin
D. Triglyceride
[1]
8. Why is the shape of an enzyme’s active site important?
A. It allows the enzyme to dissolve in water.
B. It ensures the enzyme can bind to any substrate.
C. It provides specificity for a particular substrate.
D. It prevents the substrate from entering the enzyme.
[1]
9. Which element is found in proteins but not in carbohydrates?
A. Carbon
B. Hydrogen
C. Nitrogen
D. Oxygen
[1]
10. A potato cylinder is placed in a concentrated sugar solution. After one hour, the cylinder becomes soft and flexible. Why?
A. Water entered the cells by osmosis, making them turgid.
B. Water left the cells by osmosis, causing plasmolysis.
C. Sugar entered the cells by diffusion, increasing mass.
D. The cell walls dissolved in the sugar solution.
[1]
Section B: Structured Questions (40 Marks)
Answer all questions in the spaces provided.
11. Fig. 11.1 shows a diagram of a liver cell as seen under an electron microscope.
(Imagine a diagram showing a nucleus, mitochondria, rough ER, and Golgi apparatus)
(a) Identify the structure labelled X which appears as a stack of flattened sacs.
_________________________________________________________________________ [1]
(b) State the function of structure X.
_________________________________________________________________________ [1]
(c) Liver cells contain a large number of mitochondria. Explain why.
_________________________________________________________________________ [2]
(d) The nucleus contains DNA. Describe the structure of a DNA molecule.
_________________________________________________________________________ [3]
12. Enzymes are biological catalysts. Fig. 12.1 shows the effect of pH on the activity of two enzymes, Enzyme A and Enzyme B.
(Imagine a graph: Enzyme A peaks at pH 2, Enzyme B peaks at pH 8)
(a) State the optimum pH for Enzyme A.
_________________________________________________________________________ [1]
(b) Suggest where in the human digestive system Enzyme A is likely to be found. Explain your answer.
_________________________________________________________________________ [2]
(c) Explain what happens to Enzyme B when the pH is changed from 8 to 2.
_________________________________________________________________________ [3]
13. A student investigated the effect of temperature on the rate of reaction of the enzyme amylase on starch. The results are shown in Table 13.1.
| Temperature (°C) | Time taken for starch to disappear (seconds) |
|---|---|
| 20 | 120 |
| 30 | 60 |
| 40 | 30 |
| 50 | 45 |
| 60 | > 300 (starch remained) |
(a) Calculate the rate of reaction at 30°C. (Rate = 1 / time). Give your answer to 3 decimal places.
_________________________________________________________________________ [1]
(b) Describe the trend in the rate of reaction as the temperature increases from 20°C to 40°C.
_________________________________________________________________________ [2]
(c) Explain why no starch digestion occurred at 60°C.
_________________________________________________________________________ [3]
14. Fig. 14.1 shows a section through a leaf.
(Imagine a cross-section of a leaf showing upper epidermis, palisade mesophyll, spongy mesophyll, lower epidermis, and stomata)
(a) Identify the tissue labelled Y which contains cells packed with chloroplasts.
_________________________________________________________________________ [1]
(b) Explain how the structure of tissue Y is adapted for its function in photosynthesis.
_________________________________________________________________________ [2]
(c) Stomata are found mainly on the lower epidermis. State the function of stomata.
_________________________________________________________________________ [1]
(d) Explain how the opening and closing of stomata is controlled.
_________________________________________________________________________ [3]
15. Biological molecules can be identified using chemical tests.
(a) Complete Table 15.1 to show the test reagents and positive results for starch and protein.
| Molecule | Test Reagent | Positive Result |
|---|---|---|
| Starch | Iodine solution | _________________________ |
| Protein | _________________________ | Purple / Violet colour |
[2]
(b) A food sample was tested with Benedict’s solution. The solution remained blue after heating.
(i) What does this indicate about the food sample?
_________________________________________________________________________ [1]
(ii) Describe how you would modify the test to check for the presence of non-reducing sugars (e.g., sucrose).
_________________________________________________________________________ [3]
16. Fig. 16.1 shows a model of cell membrane transport.
(Imagine a diagram showing a carrier protein changing shape to move a molecule from low to high concentration, using ATP)
(a) Name the process shown in Fig. 16.1.
_________________________________________________________________________ [1]
(b) State two features in the diagram that indicate this process requires energy.
-
- _________________________________________________________________________ [2]
(c) Give one example of where this process occurs in the human body and explain its importance.
_________________________________________________________________________ [3]
17. Osmosis is the movement of water molecules.
(a) Define osmosis.
_________________________________________________________________________ [3]
(b) A plant cell is placed in distilled water.
(i) Describe what happens to the vacuole of the cell.
_________________________________________________________________________ [1]
(ii) Explain why the plant cell does not burst, unlike an animal cell.
_________________________________________________________________________ [2]
18. Proteins are essential for life.
(a) List the chemical elements found in all proteins.
_________________________________________________________________________ [1]
(b) Describe how a protein molecule is formed from amino acids.
_________________________________________________________________________ [3]
(c) State two functions of proteins in the human body, other than as enzymes.
-
- _________________________________________________________________________ [2]
19. Fig. 19.1 shows an experiment setup to investigate diffusion.
(Imagine a beaker with water and a dialysis tubing bag containing starch and glucose solution)
(a) After 30 minutes, the water in the beaker tests positive for glucose but negative for starch. Explain these results.
_________________________________________________________________________ [4]
(b) Suggest how the rate of diffusion in this experiment could be increased.
_________________________________________________________________________ [1]
20. Compare and contrast diffusion and active transport.
(a) State one similarity between diffusion and active transport.
_________________________________________________________________________ [1]
(b) State two differences between diffusion and active transport.
_________________________________________________________________________ [4]
End of Paper
Answers
TuitionGoWhere Practice Paper - Pure Biology Secondary 4
Answer Key and Marking Scheme
Version: 5 of 5
Subject: Pure Biology
Level: Secondary 4
Section A: Multiple Choice Questions (10 Marks)
| Q | Answer | Marks |
|---|---|---|
| 1 | D | 1 |
| 2 | B | 1 |
| 3 | B | 1 |
| 4 | B | 1 |
| 5 | C | 1 |
| 6 | B | 1 |
| 7 | C | 1 |
| 8 | C | 1 |
| 9 | C | 1 |
| 10 | B | 1 |
Total Section A: 10 Marks
Section B: Structured Questions (40 Marks)
11.
(a) Golgi apparatus / Golgi body [1]
(b) To modify, sort, and package proteins for secretion / To form lysosomes [1]
(c) Liver cells are metabolically active / perform many reactions (e.g., detoxification, glycogen synthesis) [1]. These processes require energy [1]. Mitochondria are the site of aerobic respiration which releases energy [1]. (Max 2 marks)
(d) Double helix structure [1]. Made of two strands / polynucleotides [1]. Held together by complementary base pairs (A-T, C-G) / hydrogen bonds between bases [1].
12.
(a) pH 2 [1]
(b) Stomach [1]. The stomach contains hydrochloric acid which creates an acidic environment (low pH) [1].
(c) The enzyme denatures [1]. The hydrogen bonds holding the tertiary structure break [1]. The shape of the active site changes [1]. The substrate no longer fits the active site / no enzyme-substrate complexes form [1]. (Max 3 marks)
13.
(a) 1 / 60 = 0.017 (or 0.0167) [1]
(b) The rate of reaction increases [1]. As temperature increases, kinetic energy of molecules increases, leading to more frequent and successful collisions between enzyme and substrate [1].
(c) The high temperature (60°C) caused the enzyme to denature [1]. The active site changed shape [1]. Starch could not bind to the active site, so no reaction occurred [1].
14.
(a) Palisade mesophyll [1]
(b) Cells are columnar / arranged vertically to pack many cells in a layer [1]. Contains many chloroplasts to maximize light absorption for photosynthesis [1].
(c) To allow gas exchange (entry of CO2 and exit of O2/water vapour) [1].
(d) Guard cells surround the stoma [1]. When guard cells take in water by osmosis, they become turgid and swell, causing the stoma to open [1]. When they lose water, they become flaccid and the stoma closes [1].
15.
(a)
Starch: Blue-black colour [1]
Protein: Biuret solution [1]
(b)
(i) No reducing sugars are present [1].
(ii) Hydrolyse the sample with dilute acid (e.g., HCl) by heating [1]. Neutralize the solution with alkali (e.g., sodium hydrogen carbonate) [1]. Then perform the Benedict’s test again [1].
16.
(a) Active transport [1]
(b) 1. Movement against concentration gradient (low to high) [1].
2. Use of ATP / Energy source shown [1].
(c) Absorption of glucose / ions in the small intestine / kidney tubules [1]. Allows absorption even when concentration in the lumen is lower than in the blood/cells [1]. Ensures all nutrients/ions are absorbed from the filtrate/food [1].
17.
(a) The net movement of water molecules [1] from a region of higher water potential to a region of lower water potential [1] through a partially permeable membrane [1].
(b)
(i) The vacuole expands / increases in size [1].
(ii) Plant cells have a rigid cell wall [1]. The cell wall exerts pressure (turgor pressure) that prevents the cell from bursting [1]. Animal cells lack a cell wall.
18.
(a) Carbon, Hydrogen, Oxygen, Nitrogen [1] (Sulphur is also acceptable but not required for "all")
(b) Amino acids are joined together by condensation reactions [1]. A peptide bond is formed between the amino group of one amino acid and the carboxyl group of another [1]. This forms a polypeptide chain which folds into a specific 3D shape [1].
(c) Any two from:
- Structural components (e.g., muscle fibres, hair, nails)
- Transport (e.g., haemoglobin)
- Defense (e.g., antibodies)
- Hormones (e.g., insulin)
[2]
19.
(a) Glucose molecules are small [1]. They can pass through the pores of the dialysis tubing by diffusion [1]. Starch molecules are large / macromolecules [1]. They are too large to pass through the pores of the dialysis tubing [1].
(b) Increase the temperature / Stir the water in the beaker / Increase the surface area of the tubing [1].
20.
(a) Both involve the movement of molecules / substances across a membrane [1].
(b)
- Diffusion does not require energy (passive); Active transport requires energy (ATP) [2].
- Diffusion moves substances down the concentration gradient (high to low); Active transport moves substances against the concentration gradient (low to high) [2].
Total Section B: 40 Marks
Grand Total: 50 Marks