CAIE A Level Biology 9700 · Transport in mammals
During exercise, respiring tissues produce large amounts of carbon dioxide. In a red blood cell, carbon dioxide is converted to carbonic acid by carbonic anhydrase. Describe the subsequent chloride shift that occurs in the red blood cell and explain its importance in carbon dioxide transport.
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.
Describe means: Say what happens or what something is like, in order and with detail. You are not being asked why. If there is data, quote it: name the trend, then give figures with units at the points where it changes.
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