Biology 9700 · AS & A Level · Infectious diseases

Infectious diseases — practice question

The HIV/AIDS pandemic has had a major effect on life expectancy in many African countries. Table 3.1 presents estimated figures for seven African countries for the average life expectancy of someone born in 2002, the percentage of the population who tested positive for HIV in 2002, and the average life expectancy of someone born in 2002 if the HIV/AIDS pandemic had not occurred.
(a)[2]

Using the ‘without HIV/AIDS’ and ‘with HIV/AIDS’ figures in Table 3.1, calculate the percentage fall in life expectancy for Botswana. Show your working and round your answer to the nearest whole number.

(b)[2]

Suggest two reasons for the differences in estimated life expectancy without HIV/AIDS among the various African countries.

(c(i))[2]

Using Table 3.1, explain why the data do not completely support the student’s claim that there is a correlation between the percentage of the population testing positive for HIV and the fall in estimated life expectancy with HIV/AIDS.

(c(ii))[2]

State two measures used in the prevention and control of HIV/AIDS that would help to improve average life expectancy in the African countries shown in Table 3.1.

(d)[5]

A person who is confirmed as HIV-positive has tested positive for antibodies to HIV. Outline the events that take place in a newly infected person and lead to the production of antibodies to HIV.

Worked solution & mark scheme

This 13-mark question has a full step-by-step worked solution and mark scheme. One marking point: Correct result obtained as $53\%$ (or $53.2\%$) from $(38.5/72.4) \times 100$.

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