2.43B Stomata and gas exchange
Exam question
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What controls the opening and closing of stomata?
(1)Total for this question: 1 mark
2(g) GAS EXCHANGE · EXAM QUESTIONS
2.43B Stomata and gas exchange
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2.43B Stomata and gas exchange
Exam question
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Describe how guard cells open a stoma.
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Total for this question: 3 marks
2.43B Stomata and gas exchange
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Explain why stomata close when a plant is short of water.
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Total for this question: 2 marks
2.43B Stomata and gas exchange
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Explain why closing stomata on a hot day reduces the rate of photosynthesis.
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Total for this question: 2 marks
2.43B Stomata and gas exchange
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Explain why stomata usually open in the light and close in the dark.
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Total for this question: 2 marks
2.43B Stomata and gas exchange
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Guard cells have chloroplasts, unlike most epidermal cells. Suggest how this helps a stoma to open in light.
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Total for this question: 2 marks
2.43B Stomata and gas exchange
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Explain how the stomata allow both gas exchange and water loss.
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Total for this question: 2 marks
2.43B Stomata and gas exchange
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Mean stomatal width during one day Time Width / µm 03:00 0.5 06:00 2.0 09:00 6.5 12:00 8.0 15:00 6.0 18:00 3.0 21:00 0.6 Illustrative data, not from a real investigation. The table shows stomatal opening across a day. Describe the pattern.
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Total for this question: 2 marks
2.43B Stomata and gas exchange
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Mean stomatal width during one day Time Width / µm 03:00 0.5 06:00 2.0 09:00 6.5 12:00 8.0 15:00 6.0 18:00 3.0 21:00 0.6 Illustrative data, not from a real investigation. Use the table to explain why the rate of carbon dioxide uptake is highest around midday.
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Total for this question: 2 marks
2.43B Stomata and gas exchange
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Predict how stomatal width would change if the plant was kept in constant darkness for a day. Explain your prediction.
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Total for this question: 2 marks
2.43B Stomata and gas exchange
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Stomatal density of leaves from the same species was lower in plants grown at high carbon dioxide concentration. Suggest why this is an advantage to the plant.
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Total for this question: 2 marks