CAIE A Level Biology 9700 · Enzymes
A student measures the activity of two enzymes, P and Q, which catalyse the same reaction. The Michaelis-Menten constant (Km) for enzyme P is 0.4 mmol dm−3 and for enzyme Q is 2.0 mmol dm−3.
Compare the affinities of enzymes P and Q for their substrate. Use the meaning of Km in your answer.
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.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.