What this practice covers
These questions are drawn from past CIE 0654 Co-ordinated Sciences papers and filtered to enzymes. 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 enzymes, taken from our own topic notes. Read them before you practise and you will recognise the traps in the questions.
- Calling enzymes carbohydrates, fats or hormones. They are proteins.
- Leaving nitrogen off the list of elements in an enzyme.
- Saying enzymes are used up in the reaction.
- Saying low temperatures denature enzymes. Low temperatures only slow them down.
- Explaining the fall after the optimum by "fewer collisions". Collisions are more frequent; the active site has changed shape.
- Saying a denatured enzyme recovers on cooling.
- Saying the active site is the same shape as the substrate rather than complementary to it.
- Saying the substrate is denatured.
Revise it first
If any of the above is unfamiliar, work through the notes before practising: Enzymes revision notes.