CAIE A Level Biology 9700 · Transport in mammals
During vigorous exercise, muscle cells produce large amounts of carbon dioxide. This carbon dioxide diffuses into the blood plasma and then enters red blood cells. Explain the role of the enzyme carbonic anhydrase in the transport of carbon dioxide from respiring tissues to the lungs.
4 marks, so the mark scheme is looking for about 4 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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