3.4 Common infections: cholera, TB, Chalara, malaria and HIV
6 exam questions worth 15 marks. Write your answer, open the mark scheme, then give yourself the marks you earned. Your answers are saved on this device.
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Which disease is caused by a fungus?
Choose one answer.
Correct Not quite: the answer is Chalara ash dieback
Mark scheme
C: Chalara ash dieback
Model answer
C: Chalara ash dieback is caused by a fungus.
Cholera is common in places without clean water.
Explain why, and give one way to prevent its spread.
Mark scheme
- cholera bacteria are spread in (contaminated) water (1)
- water contaminated with faeces of infected people (1)
- provide clean water / treat sewage / boil water (1)
Model answer
Cholera bacteria spread in water contaminated with faeces from infected people. Providing clean drinking water and treating sewage prevents this.
Describe how tuberculosis is spread and give two ways its spread can be reduced.
Mark scheme
- airborne / droplets from coughing (1)
- any two from: isolation / ventilation / avoid overcrowding / BCG vaccination / complete antibiotic course (2)
Model answer
TB spreads through the air in droplets when infected people cough. It can be reduced by isolating infected people and vaccinating with the BCG vaccine.
Give two ways to reduce the spread of Chalara ash dieback.
Mark scheme
Any two from:
- remove (and destroy) infected trees (1)
- replant with different species (1)
- restrict import / movement of ash trees (1)
Model answer
Remove infected young ash trees and stop ash trees being imported or moved around.
Name the parts of the body damaged by malaria, and the vector that spreads it.
Mark scheme
- blood and liver (1)
- mosquito (1)
Model answer
Malaria damages the blood and liver, and is spread by mosquitoes.
Explain how HIV leads to AIDS and describe two ways its spread can be prevented.
Mark scheme
- HIV destroys / infects white blood cells (1)
- immune system cannot fight other infections (AIDS) (1)
- any two from: condoms / not sharing needles / screening blood / antiretroviral drugs (2)
Model answer
HIV destroys white blood cells, so the immune system gets weaker until it cannot fight other infections. This is AIDS. Using condoms and not sharing needles prevent its spread.
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