CAIE A Level Biology 9700 · Enzymes
In human liver cells, two different enzymes (Enzyme P and Enzyme Q) catalyse the same reaction: the phosphorylation of glucose to glucose-6-phosphate. Their Km values for glucose are shown in the table below.
| Enzyme | Km for glucose (mM) |
|---|---|
| P | 0.05 |
| Q | 10.0 |
Compare the affinity of Enzyme P and Enzyme Q for glucose. Explain what the Km value represents and how it is related to Vmax.
7 marks, so the mark scheme is looking for about 7 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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