CAIE A Level Biology 9700 · Energy and respiration

Energy and respiration: explain question

Explain6 marksChallenge

A biologist compares the energy released from the complete oxidation of equal masses (1 g each) of a typical carbohydrate (starch) and a typical lipid (triacylglycerol). Explain why the lipid releases more energy per gram than the carbohydrate.

How this question is marked

6 marks, so the mark scheme is looking for about 6 separate creditworthy points. Making the same point twice in different words earns it once.

Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.

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