CAIE A Level Biology 9700 · Transport in mammals
During strenuous exercise, muscle cells produce large amounts of carbon dioxide (CO₂). Explain how this increased CO₂ concentration affects the oxygen dissociation curve of haemoglobin and why this is important for oxygen delivery to the active muscles.
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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