O-LevelBiologyCoordination & Response5090/11 · Oct/Nov 2023 · Q221 Mark

Human immunodeficiency virus (HIV) affects the immune system resulting in decreased lymphocyte numbers. The diagnosis of AIDS can be made when lymphocyte numbers decrease below 200 cells/mm³ of blood. The graph shows the lymphocyte numbers after HIV infection in a patient. How many years after infection would this patient be diagnosed with AIDS?

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A0 years

B3 years

C7 years

D9 years

✓ Correct answer

D: 9 years

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Topic: Coordination & Response, O-Level Biology (syllabus 5090). Multiple choice, 1 mark.
Source: O-Level Biology, Oct/Nov 2023 Paper 1 Variant 1, question 22.

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