CAIE A Level Biology 9700 · Enzymes
A student investigates the effect of pH on the activity of an enzyme, using buffer solutions to maintain constant pH. The table below shows the relative activity of the enzyme at various pH values.
| pH | Relative activity (%) |
|---|---|
| 3 | 0 |
| 4 | 5 |
| 5 | 20 |
| 6 | 70 |
| 7 | 100 |
| 8 | 75 |
| 9 | 30 |
| 10 | 10 |
Compare the activity of this enzyme at pH 4, pH 7, and pH 10. Explain the reasons for the differences in activity.
5 marks, so the mark scheme is looking for about 5 separate creditworthy points. Making the same point twice in different words earns it once.
Compare means: Give similarities or differences between two things, and say which side each point belongs to. Write each point as a pair, for example: A is X, whereas B is Y. Two separate descriptions rarely earn the marks.
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