What this practice covers
These questions are drawn from past CIE 9700 Biology papers and filtered to testing for biological molecules. 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 testing for biological molecules, taken from our own topic notes. Read them before you practise and you will recognise the traps in the questions.
- Saying "Benedict's turns red" without naming the intermediate colours. A question showing green or yellow is testing the range.
- Forgetting to neutralise after acid hydrolysis in the non-reducing sugar test.
- Heating the Biuret test. It does not need it and the mark scheme does not credit it.
- Saying the Biuret test detects amino acids. It detects the peptide bond.
- Adding water before ethanol in the emulsion test, which gives no emulsion.
Revise it first
If any of the above is unfamiliar, work through the notes before practising: Testing for biological molecules revision notes.