23 exam-style questions · Biology only (B): not in Science (Double Award). Write your answer, check it against the mark scheme and tick the points you earned. Your marks stay on this device. Your writing is not saved.
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2.14B pH and enzyme activity
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At pH 7, starch was fully digested by amylase in 80 s. Calculate the rate of reaction (1 ÷ time). Give your answer to 4 decimal places.
(2)Total for this question: 2 marks
2.14B pH and enzyme activity
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At pH 5, the same reaction took 210 s. Calculate the rate as 1 ÷ time to 4 decimal places.
(2)Total for this question: 2 marks
2.14B pH and enzyme activity
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A protease at pH 3 took 45 s to clear a cloudy egg-white suspension. Calculate the rate of reaction (1 ÷ time) to 3 decimal places.
(2)Total for this question: 2 marks
2.14B pH and enzyme activity
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Describe a method to find out how pH changes the rate at which amylase digests starch.
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Total for this question: 4 marks
2.14B pH and enzyme activity
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Explain why a buffer is used in the amylase pH investigation.
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Total for this question: 2 marks
2.14B pH and enzyme activity
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Explain why the temperature should be kept constant in a pH investigation.
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Total for this question: 2 marks
2.14B pH and enzyme activity
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Suggest why a spotting tile with iodine is checked every 10 s rather than every 60 s.
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Total for this question: 2 marks
2.14B pH and enzyme activity
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A student finds no colour change in iodine samples after 10 minutes at pH 2. Explain this result.
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Total for this question: 2 marks
2.14B pH and enzyme activity
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Describe how to find the time taken for amylase to digest all the starch.
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Total for this question: 2 marks
2.14B pH and enzyme activity
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Suggest one source of error in the iodine–spotting tile method and how to reduce it.
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Total for this question: 2 marks
2.14B pH and enzyme activity
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Explain how the results of a pH investigation could be used to find the optimum pH of amylase.
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Total for this question: 3 marks
2.14B pH and enzyme activity
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A student timed amylase at pH 7 three times: 62 s, 58 s and 63 s. Calculate the mean time to 1 decimal place.
(2)Total for this question: 2 marks
2.14B pH and enzyme activity
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At pH 9 the times were 95 s, 101 s and 99 s. Calculate the mean time to 1 decimal place.
(2)Total for this question: 2 marks
2.14B pH and enzyme activity
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| pH | Repeat 1 / s | Repeat 2 / s | Repeat 3 / s |
|---|---|---|---|
| 5 | 150 | 146 | 154 |
| 6 | 92 | 130 | 95 |
| 7 | 64 | 60 | 66 |
Identify the anomalous result in the table.
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Total for this question: 1 mark
2.14B pH and enzyme activity
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Explain why anomalous results should be left out when calculating a mean.
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Total for this question: 2 marks
