CAIE A Level Biology 9700 · Enzymes
The table below shows the Michaelis-Menten constant (Km) values for two different enzymes, A and B, that both catalyse the same reaction.
| Enzyme | Km (mM) |
|---|---|
| A | 0.2 |
| B | 2.5 |
Compare the affinities of enzyme A and enzyme B for their substrate. Explain the relationship between Km and affinity, and describe how the value of Km is determined from experimental data.
4 marks, so the mark scheme is looking for about 4 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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