CAIE A Level Biology 9700 · Immunity
A patient receives a kidney transplant from an unrelated donor. The donated kidney expresses proteins (antigens) that are different from the patient's own proteins. The patient's immune system has not encountered these antigens before.
Compare the roles of macrophages and B-lymphocytes in the primary immune response to the transplanted kidney. In your answer, explain why the patient's immune system does not normally attack their own kidney cells.
6 marks, so the mark scheme is looking for about 6 separate creditworthy points. Making the same point twice in different words earns it once.
Compare means: Give similarities or differences between two things, and say which side each point belongs to. Write each point as a pair, for example: A is X, whereas B is Y. Two separate descriptions rarely earn the marks.
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