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Date May 2021 Marks available 1 Reference code 21M.1.HL.TZ2.37
Level Higher level Paper Paper 1 Time zone Time zone 2
Command term Question number 37 Adapted from N/A

Question

The graph shows changes in the concentration of an antibody in the blood of an individual subjected to two separate infections at time X and time Y.

[Source: Illustration from Anatomy & Physiology, Connexions Web site. http://cnx.org/content/col11496/1.6/, Jun 19, 2013 OpenStax College © 1999-2021, Rice University. Except where otherwise noted, textbooks on this site are licensed under a Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/).]

 

What distinguishes the events occurring at Y from those occurring at X?

A. The individual was infected with different pathogens at X and Y.

B. Memory B cells are involved in antibody production at Y but not at X.

C. There is no clonal selection involved.

D. There are no T lymphocytes involved.

Markscheme

B

Examiners report

This question was the easiest on the paper for the candidates with 89 % selecting the correct response.

Syllabus sections

Additional higher level » Topic 11: Animal physiology » 11.1 Antibody production and vaccination
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