CAIE A Level Biology 9700 · Cell membranes and transport
In mammals, cell surface membranes contain cholesterol. Explain how cholesterol affects membrane fluidity at both low and high temperatures. In your answer, refer to the interactions between cholesterol and phospholipids in the bilayer.
5 marks, so the mark scheme is looking for about 5 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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