CAIE A Level Biology 9700 · Enzymes
A student investigates the effect of substrate concentration on the initial rate of an enzyme-catalysed reaction. The enzyme is maintained at its optimum temperature and pH. The initial rate is measured at various substrate concentrations. Describe the relationship between substrate concentration and initial rate and explain why the rate reaches a maximum. In your answer, use the terms Vmax and Km.
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.
Describe means: Say what happens or what something is like, in order and with detail. You are not being asked why. If there is data, quote it: name the trend, then give figures with units at the points where it changes.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.