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Exam questions · Biology · Communicable Diseases

Viral Diseases

  • 7 exam questions
  • 18 marks
  • 8 quick checks
  1. 1 State [1 mark]

    Name the virus that causes a mosaic pattern of discolouration on the leaves of tomato plants.

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    Model answer

    Tobacco mosaic virus (TMV).

    Mark scheme

    • Tobacco mosaic virus — 1 mark
  2. 2 Describe [2 marks]

    Describe the symptoms of measles.

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    Model answer

    A fever and a red skin rash.

    Mark scheme

    • Fever — 1 mark
    • Red skin rash — 1 mark
  3. 3 Explain [2 marks]

    Explain why most young children are vaccinated against measles.

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    Model answer

    Measles is a serious illness that can be fatal if complications arise. Vaccination protects the children and reduces the spread of the virus.

    Mark scheme

    • Serious / can be fatal — 1 mark
    • Vaccination protects / prevents the spread — 1 mark
  4. 4 Describe [3 marks]

    Describe how HIV is spread between people.

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    Model answer

    HIV is spread by sexual contact. It is also spread by the exchange of body fluids such as blood, for example when drug users share needles.

    Mark scheme

    • Sexual contact — 1 mark
    • Exchange of body fluids / blood — 1 mark
    • Sharing needles as an example — 1 mark
  5. 5 Explain [3 marks]

    Explain how HIV can lead to AIDS.

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    Model answer

    HIV attacks the body's immune cells. Over time the immune system is so badly damaged that it can no longer deal with other infections or cancers. This late stage of the infection is called AIDS.

    Mark scheme

    • Attacks immune cells — 1 mark
    • Immune system badly damaged — 1 mark
    • Cannot deal with other infections or cancers — 1 mark
  6. 6 Explain [3 marks]

    Explain why a plant infected with tobacco mosaic virus does not grow well.

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    Model answer

    The virus makes patches of the leaves lose their chlorophyll, giving a mosaic pattern. There is less photosynthesis in the leaves, so the plant makes less glucose and cannot grow properly.

    Mark scheme

    • Mosaic / discolouration of leaves — 1 mark
    • Less photosynthesis — 1 mark
    • Less glucose so poor growth — 1 mark
  7. 7 Suggest [4 marks]

    Suggest how the spread of measles and the spread of HIV could each be reduced.

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    Model answer

    Measles spreads in droplets, so it can be reduced by vaccinating children and by isolating people who are infected. HIV spreads by body fluids, so it can be reduced by using condoms during sex, by not sharing needles, and by treating infected people with antiretroviral drugs.

    Mark scheme

    • Measles: vaccination — 1 mark
    • Measles: isolation — 1 mark
    • HIV: condoms or not sharing needles — 1 mark
    • HIV: antiretroviral drugs — 1 mark

Quick check

  1. 1

    Which disease causes a fever and a red skin rash?

    1. AHIV
    2. BMeasles
    3. CMalaria
    4. DRose black spot
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    B: Measles

    Fever and a red skin rash are symptoms of measles.

  2. 2

    How is measles spread?

    1. ABy sexual contact
    2. BBy sharing needles
    3. CBy droplets from coughs and sneezes
    4. DBy mosquitoes
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    C: By droplets from coughs and sneezes

    The measles virus is spread by breathing in droplets from coughs and sneezes.

  3. 3

    What does HIV attack?

    1. AImmune cells
    2. BRed blood cells
    3. CPalisade cells
    4. DPlatelets
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    A: Immune cells

    HIV attacks the immune cells, which weakens the body's defences.

  4. 4

    What is the name for late-stage HIV infection?

    1. AMeasles
    2. BMosaic
    3. CMalaria
    4. DAIDS
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    D: AIDS

    AIDS is the late stage, when the immune system can no longer fight other infections.

  5. 5

    Which of these affects plants?

    1. AHIV
    2. BMeasles
    3. CTobacco mosaic virus
    4. DGonorrhoea
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    C: Tobacco mosaic virus

    Tobacco mosaic virus infects the leaves of many plants.

  6. 6

    Why does TMV reduce a plant's growth?

    1. AIt kills the roots
    2. BIt reduces photosynthesis
    3. CIt blocks the xylem
    4. DIt makes the plant too tall
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    B: It reduces photosynthesis

    The discoloured leaf patches carry out less photosynthesis.

  7. 7

    How can the spread of HIV be reduced?

    1. AUsing condoms and not sharing needles
    2. BWashing the leaves
    3. CCooking food thoroughly
    4. DDraining standing water
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    A: Using condoms and not sharing needles

    Condoms and not sharing needles reduce contact with infected body fluids.

  8. 8

    What controls HIV in an infected person?

    1. APenicillin
    2. BFungicides
    3. CPainkillers
    4. DAntiretroviral drugs
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    D: Antiretroviral drugs

    Antiretroviral drugs control the virus.