A Level H1 Biology Plant Biology Quiz

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A-Level Biology H1 Quiz - Plant Biology

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

Duration: 45 minutes
Total Marks: 40
Instructions:

1. Answer all questions.
2. Write your answers in the spaces provided.
3. The number of marks is indicated in brackets [ ] at the end of each question or part question.
4. Use clear scientific terminology and refer to diagrams where requested.

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Section A: Chloroplast Structure and Light-Dependent Reactions (Questions 1-5)

1. Fig. 1.1 shows a cross-section of a chloroplast.

(Note: Imagine Fig 1.1 shows a chloroplast with labeled structures A (thylakoid stack/granum), B (stroma), and C (outer membrane).)

(a) Identify structure A. [1]

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(b) State one specific process of photosynthesis that occurs in structure A. [1]

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2. Structure B in Fig. 1.1 is the stroma.

(a) Name the cycle of reactions that occurs in the stroma. [1]

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(b) Explain why the stroma contains high concentrations of the enzyme RuBisCO. [1]

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3. During the light-dependent stage, water molecules are split in a process called photolysis.

(a) State the location within the chloroplast where photolysis occurs. [1]

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(b) State one product of photolysis that is used to replace electrons in Photosystem II. [1]

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4. The splitting of water also produces protons ($H^+$) and oxygen.

(a) Describe the immediate fate of the protons ($H^+$) produced by photolysis. [1]

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(b) What happens to the oxygen produced? [1]

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5. Herbicide X blocks the electron transport chain between Photosystem II and Photosystem I.

(a) State the effect of Herbicide X on the production of ATP. [1]

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(b) State the effect of Herbicide X on the production of reduced NADP. [1]

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Section B: The Calvin Cycle and Limiting Factors (Questions 6-10)

6. Fig. 6.1 illustrates the Calvin cycle.

(Note: Imagine Fig 6.1 shows the cycle involving RuBP, GP, TP, and regeneration steps.)

(a) Identify the 5-carbon compound that accepts carbon dioxide in the first step of the cycle. [1]

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(b) Name the 3-carbon compound formed immediately after carbon dioxide fixation. [1]

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7. The conversion of GP (glycerate-3-phosphate) to TP (triose phosphate) requires energy and reducing power.

(a) Name the molecule that provides the energy for this conversion. [1]

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(b) Name the molecule that provides the hydrogen/electrons for this reduction. [1]

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8. A student investigated the effect of light intensity on the rate of photosynthesis. Table 8.1 shows the results.

Table 8.1

Light Intensity (arb. units)	Rate of $O_2$ Production (cm³ min⁻¹)
0	0.0
10	1.5
20	2.4
30	2.4

(a) Describe the trend in the rate of photosynthesis as light intensity increases from 0 to 20 arbitrary units. [1]

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9. Refer to Table 8.1 again.

(a) Explain why the rate of oxygen production remains constant between 20 and 30 arbitrary units. [1]

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10. In the experiment in Table 8.1, light was no longer the limiting factor at 30 arbitrary units.

(a) Suggest one other factor that could be limiting the rate of photosynthesis at this intensity. [1]

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Section C: C4 Plants and Environmental Adaptations (Questions 11-15)

11. C4 plants, such as maize, possess Kranz anatomy.

(a) Describe the arrangement of cells in Kranz anatomy. [1]

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12. C4 plants use a different enzyme for the initial fixation of carbon dioxide compared to C3 plants.

(a) Name the enzyme used for initial $CO_2$ fixation in C4 plants. [1]

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13. Photorespiration is a wasteful process that occurs in C3 plants under certain conditions.

(a) State the condition that promotes photorespiration in C3 plants. [1]

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14. C4 plants are adapted to hot, dry environments.

(a) State one advantage of the C4 pathway regarding water loss. [1]

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15. The C4 pathway reduces photorespiration.

(a) Explain how the C4 pathway ensures a high concentration of $CO_2$ at the site of RuBisCO. [1]

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Section D: Membrane Transport and Experimental Analysis (Questions 16-20)

16. Photosynthesis relies on the movement of substances across membranes.

(a) Name the process by which carbon dioxide enters the leaf from the atmosphere. [1]

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17. Water is essential for photosynthesis.

(a) Name the process by which water enters root hair cells from the soil. [1]

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18. The thylakoid membrane plays a critical role in ATP synthesis.

(a) Explain why the thylakoid membrane must be impermeable to protons ($H^+$). [1]

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19. Researchers measured the uptake of radioactive $^{14}CO_2$. In one experiment, light was switched off while $CO_2$ was still present.

(a) State what happens to the level of GP (glycerate-3-phosphate) when the light is switched off. [1]

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20. In the same experiment as Question 19:

(a) State what happens to the level of TP (triose phosphate) when the light is switched off. [1]

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A-Level Biology H1 Quiz - Plant Biology (Answer Key)

Total Marks: 40

Section A: Chloroplast Structure and Light-Dependent Reactions

1.
(a) Granum / Thylakoid stack. [1]
(b) Light-dependent reaction / Photolysis / Photophosphorylation. [1]

2.
(a) Calvin cycle / Light-independent reaction. [1]
(b) RuBisCO catalyzes the fixation of $CO_2$ to RuBP, which occurs in the stroma. [1]

3.
(a) Thylakoid lumen / Inside the thylakoid. [1]
(b) Electrons. [1]

4.
(a) They accumulate in the thylakoid lumen to create a proton gradient. [1]
(b) It is released as a by-product / Diffuses out of the leaf. [1]

5.
(a) ATP production stops / Decreases. [1]
(b) Reduced NADP production stops / Decreases. [1]

Section B: The Calvin Cycle and Limiting Factors

6.
(a) Ribulose bisphosphate (RuBP). [1]
(b) Glycerate-3-phosphate (GP). [1]

7.
(a) ATP. [1]
(b) Reduced NADP. [1]

8.
(a) The rate increases. [1]

9.
(a) Light is no longer the limiting factor; another factor (e.g., $CO_2$ or temperature) is limiting. [1]

10.
(a) Carbon dioxide concentration OR Temperature. [1]

Section C: C4 Plants and Environmental Adaptations

11.
(a) Bundle sheath cells surround the vascular bundles. [1]

12.
(a) PEP carboxylase. [1]

13.
(a) High temperature / Low $CO_2$ concentration / High oxygen concentration. [1]

14.
(a) Stomata can be partially closed to reduce transpiration/water loss. [1]

15.
(a) $CO_2$ is released from the 4-carbon compound in bundle sheath cells, creating a high local concentration. [1]

Section D: Membrane Transport and Experimental Analysis

16.
(a) Diffusion. [1]

17.
(a) Osmosis. [1]

18.
(a) To allow the establishment/maintenance of a proton gradient for chemiosmosis. [1]

19.
(a) GP levels increase / Rise. [1]

20.
(a) TP levels decrease / Fall. [1]