What this practice covers
These questions are drawn from past CIE 9700 Biology papers and filtered to energy and respiration. 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 energy and respiration, taken from our own topic notes. Read them before you practise and you will recognise the traps in the questions.
- Calling ATP an energy store rather than a currency, or saying it "contains" energy, when the energy is released by the hydrolysis of a bond.
- Placing glycolysis in the mitochondrion. It is in the cytoplasm, in every eukaryote and every prokaryote.
- Forgetting that glycolysis invests two ATP, and quoting a gross yield of four rather than a net yield of two.
- Saying oxygen is used in the Krebs cycle. Oxygen is used only at the end of the electron transport chain.
- Writing that oxygen "accepts hydrogen" without saying it is the final electron acceptor forming water.
- Explaining anaerobic respiration as producing less ATP "because there is no oxygen", without saying that the reduced NAD is never oxidised by the chain and so no protons are pumped.
- Saying fermentation makes ATP. Neither fermentation pathway makes any ATP; both exist only to regenerate NAD so that glycolysis can continue.
- Reading an RQ above 1.0 as an error. It is the signature of anaerobic respiration alongside aerobic.
Revise it first
If any of the above is unfamiliar, work through the notes before practising: Energy and respiration revision notes.