A scientist compared antibody levels in the blood of two patients over 30 days. Patient X was infected with pathogen P for the first time. Patient Y had been infected with pathogen P six months earlier and was re-infected. Which statement best explains the difference in immune response between the two patients?

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Question

A scientist compared antibody levels in the blood of two patients over 30 days. Patient X was infected with pathogen P for the first time. Patient Y had been infected with pathogen P six months earlier and was re-infected. Which statement best explains the difference in immune response between the two patients?

Accepted Answer

Patient Y's memory cells enable a faster and stronger antibody response — Award 1 mark for recognizing that Patient Y's previous infection created memory cells that enable a faster secondary immune response with higher antibody levels. B is incorrect because Patient Y already has memory cells from the first infection. C is incorrect because previous infection strengthens, not weakens, the specific immune response. D is incorrect because the primary immune response (Patient X) has a lag phase before antibody production peaks.

Answer

Patient X produces antibodies immediately without a delay

Answer

Patient X produces more memory cells than Patient Y

Answer

Patient Y's immune system is weaker due to the previous infection

Answer

Patient Y's memory cells enable a faster and stronger antibody response

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