CAIE A Level Biology 9700 · Enzymes

Enzymes: explain question

Explain5 marksStandard

Salivary amylase catalyses the hydrolysis of starch into maltose. It does not catalyse the hydrolysis of cellulose, even though both starch and cellulose are polysaccharides composed of glucose monomers.

Explain why amylase acts only on starch and not on cellulose.

How this question is marked

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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