CAIE A Level Biology 9700 · Immunity
A healthy individual receives a vaccination against a viral pathogen. Five years later, the individual is exposed to the same virus but does not become ill. Explain why the secondary immune response is faster and larger than the primary response, with reference to the roles of memory cells.
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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