CAIE A Level Biology 9700 · Energy and respiration

Energy and respiration: explain question

Explain6 marksChallenge

A skeletal muscle cell is actively transporting calcium ions into the sarcoplasmic reticulum, a process that requires a substantial input of energy. Explain why ATP is described as the universal energy currency for this process.

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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