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Exam questions · Biology · Health and Infectious Disease

Sexually Transmitted Infections

  • 6 exam questions
  • 19 marks
  • 9 quick checks
  1. 1 State [2 marks]

    State two ways in which HIV can be spread.

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    Model answer

    Any two from: sexual contact; sharing needles; from mother to baby; contact with infected blood.

    Mark scheme

    • First — 1 mark
    • Second — 1 mark
  2. 2 State [2 marks]

    State the type of pathogen that causes (a) chlamydia and (b) HIV.

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    Model answer

    (a) A bacterium. (b) A virus.

    Mark scheme

    • Bacterium — 1 mark
    • Virus — 1 mark
  3. 3 Explain [3 marks]

    Explain why chlamydia can spread easily through a population.

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    Model answer

    Many people who are infected have no symptoms, so they do not know they have the infection and do not get treated. They can pass it on without realising it. It is also spread by sexual contact, which is common.

    Mark scheme

    • Many have no symptoms — 1 mark
    • Do not know / not treated — 1 mark
    • Pass it on — 1 mark
  4. 4 Explain [3 marks]

    Explain how a condom reduces the spread of both chlamydia and HIV.

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    Model answer

    A condom is a barrier that stops body fluids, which contain the bacteria and the virus, from passing from one person to the other during sex. This breaks the route of transmission, so the pathogens are not passed on.

    Mark scheme

    • Acts as a barrier — 1 mark
    • Stops body fluids passing — 1 mark
    • Breaks the route of transmission — 1 mark
  5. 5 Calculate [3 marks]

    In a screening programme, 500 of 8000 people tested positive for chlamydia in year 1, and 320 of 8000 tested positive in year 2. Calculate the percentage reduction in the number of positive tests.

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    Model answer

    The fall is 500 − 320 = 180. The percentage reduction is 180 ÷ 500 × 100 = 36%.

    Mark scheme

    • Fall of 180 — 1 mark
    • Divides by 500 and multiplies by 100 — 1 mark
    • 36% — 1 mark
  6. 6 Evaluate [6 marks]

    Evaluate the methods that can be used to reduce the spread of HIV.

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    Model answer

    Condoms are cheap and effective at stopping the virus being passed on in sex, but they must be used correctly each time. Needle exchange programmes stop the virus being passed on by sharing needles, but they rely on people using them. Testing donated blood is very effective in stopping the spread through transfusions. Antiretroviral drugs reduce the amount of virus, so they help the infected person and can make it impossible to pass on, but they are expensive, and must be taken for life. Drugs and care for pregnant women stop the virus being passed to babies. No single method is complete, so a combination, with education and testing, is the most effective.

    Mark scheme

    • Condoms: effective, but must be used — 1 mark
    • Needle exchange — 1 mark
    • Testing blood — 1 mark
    • Antiretroviral drugs: benefit — 1 mark
    • A limitation, such as cost or lifelong — 1 mark
    • A combination is most effective — 1 mark

Quick check

  1. 1

    What type of pathogen causes chlamydia?

    1. AA virus
    2. BA bacterium
    3. CA fungus
    4. DA protist
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    B: A bacterium

    Chlamydia is caused by a bacterium.

  2. 2

    What can untreated chlamydia lead to?

    1. AAIDS
    2. BParalysis
    3. CInfertility
    4. DMalaria
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    C: Infertility

    In women it can cause pelvic inflammatory disease and infertility.

  3. 3

    How is chlamydia treated?

    1. AWith antibiotics
    2. BWith antiretroviral drugs
    3. CWith a vaccine
    4. DIt cannot be treated
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    A: With antibiotics

    It is a bacterial infection, so it is treated with antibiotics.

  4. 4

    What does HIV attack?

    1. ARed blood cells
    2. BThe liver
    3. CThe kidneys
    4. DWhite blood cells
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    D: White blood cells

    HIV destroys white blood cells, which are part of the immune system.

  5. 5

    Which of these can spread HIV?

    1. AShaking hands
    2. BSharing a cup
    3. CSharing needles
    4. DCoughing
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    C: Sharing needles

    Sharing needles can pass on blood containing HIV.

  6. 6

    How do antiretroviral drugs help people with HIV?

    1. AThey cure HIV completely
    2. BThey reduce the amount of virus
    3. CThey kill bacteria
    4. DThey destroy white blood cells
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    B: They reduce the amount of virus

    They reduce the amount of virus in the body, which protects the immune system and reduces the chance of passing it on.

  7. 7

    Why is screening useful for chlamydia?

    1. AIt finds infections in people with no symptoms
    2. BIt vaccinates people
    3. CIt cures the infection
    4. DIt stops mosquitoes
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    A: It finds infections in people with no symptoms

    Many people have no symptoms, so a test finds those who are infected so they can be treated.

  8. 8

    Why does a condom reduce the spread of STIs?

    1. AIt kills the pathogens in the body
    2. BIt cures infections
    3. CIt makes people immune
    4. DIt acts as a barrier to body fluids
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    D: It acts as a barrier to body fluids

    It acts as a barrier, so body fluids containing the pathogens cannot pass between people.

  9. 9

    Why can HIV not be cured with antibiotics?

    1. AHIV is a protist
    2. BHIV is a virus, and antibiotics only work on bacteria
    3. CHIV is a fungus
    4. DThe virus is too large
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    B: HIV is a virus, and antibiotics only work on bacteria

    HIV is a virus, and antibiotics only work on bacteria.