What this practice covers
These questions are drawn from past CIE 9700 Biology papers and filtered to factors that affect enzyme action. You answer, you find out immediately whether you were right, and you get the reasoning for the correct option and for each distractor. Wrong answers go to a mistakes locker so you can come back to exactly those.
Practice is free. You need an account only so your progress and your mistakes are still there next time.
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What examiners see students get wrong here
These are the errors that cost marks on factors that affect enzyme action, taken from our own topic notes. Read them before you practise and you will recognise the traps in the questions.
- Explaining the temperature curve with kinetic energy alone, and never mentioning denaturation.
- Saying high temperature "kills" the enzyme. An enzyme is not alive; it is denatured.
- Getting Km backwards. Low Km means high affinity.
- Saying a competitive inhibitor lowers Vmax. It does not, given enough substrate.
- Saying a non-competitive inhibitor "changes the shape of the substrate". It changes the shape of the active site.
Revise it first
If any of the above is unfamiliar, work through the notes before practising: Factors that affect enzyme action revision notes.