What this practice covers
These questions are drawn from past CIE 9700 Biology papers and filtered to proteins and water. 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 proteins and water, taken from our own topic notes. Read them before you practise and you will recognise the traps in the questions.
- Saying secondary structure involves R groups. It is backbone hydrogen bonding.
- Saying every protein has quaternary structure. Only multi-chain proteins do.
- Describing the disulfide bond as strong "because there are many of them". It is strong because it is covalent.
- Saying water molecules are held together by ionic bonds. They are hydrogen bonds between polar molecules.
- Explaining ice floating as "ice is lighter". The hydrogen bonds hold the molecules further apart than in liquid water.
Revise it first
If any of the above is unfamiliar, work through the notes before practising: Proteins and water revision notes.