Question 1

Paper 2Medium4 marks

Researchers added the same concentration of an antibiotic to bacterial cultures and to cultures of human lymphocytes, some of which were infected with HIV. Figure 1 shows measurements after 24 hours, expressed relative to the corresponding culture without antibiotic.

Same antibiotic concentration addedBacterial cultureBacterial cell number:22% of untreated cultureUninfected humanlymphocyte cultureViable lymphocyte number:98% of untreated cultureHIV-infected humanlymphocyte cultureHIV particles released:103% of untreated cultureFor each culture, the corresponding untreated value is 100%.
(a)

Compare the effect of the antibiotic on bacterial cells and uninfected human lymphocytes, using Figure 1.

[1]
(b)

Using Figure 1 and your knowledge of antibiotics, explain why the antibiotic does not control HIV.

[1]
(c)

Explain how HIV infection can result in opportunistic infections.

[2]

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