Pathogens, defences and vaccinationIB MYP Biology: Subtopic test

1. 1
   A public health team in Dhaka is investigating four illnesses in a district: cholera, influenza, athlete's foot and malaria. Each one is caused by a different type of pathogen and each one spreads in a different way.

   (a)

   Which type of pathogen causes malaria?

   [1 mark]

   • AA bacterium
   • BA virus
   • CA fungus
   • DA protist

   (b)

   How is influenza mainly spread?

   [1 mark]

   • ABy drinking contaminated water
   • BBy droplets in the air from coughs and sneezes
   • CBy the bite of a mosquito
   • DBy direct contact with soil

   (c)

   Describe how cholera is transmitted and outline one way of preventing its spread.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A student in Lima falls on rough ground and cuts her knee. That evening she also breathes in dust and swallows some food that contains a few bacteria. Over the following days she stays healthy and the cut heals.

   (a)

   Which defence kills most of the bacteria that are swallowed with food?

   [1 mark]

   • AThe skin
   • BMucus in the nose
   • CHydrochloric acid in the stomach
   • DThe platelets in the blood

   (b)

   How does mucus in the airways protect the body?

   [1 mark]

   • AIt traps pathogens, which are then moved away from the lungs
   • BIt kills pathogens with acid
   • CIt makes antibodies against the pathogens
   • DIt absorbs oxygen into the blood

   (c)

   Outline how the skin and the mucus in the airways help to prevent infection.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   Amira is 14 and lives in Amman. She has a fever and a headache. Her doctor tells her that the illness is caused by a virus and decides not to prescribe antibiotics, although her mother asks for them. Amira's white blood cells have already started to respond to the infection.

   (a)

   Describe three ways in which white blood cells defend the body against pathogens.

   [3 marks]

   (b)

   Explain why the doctor did not prescribe antibiotics for Amira, and explain how overusing antibiotics can make them less effective in the future.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   Health authorities in a South American country compare the vaccination of children against measles in two regions. In Region A, 95% of children were vaccinated and there were 12 cases of measles per 100 000 children in one year. In Region B, 60% of children were vaccinated and there were 480 cases per 100 000 children in the same year. Some parents in Region B refuse the vaccine because it can cause a sore arm or a mild fever, and very rarely an allergic reaction.

   (a)

   Describe the trend in the data, explain it using the idea of herd immunity and evaluate the data.

   [6 marks]

   (b)

   Discuss the benefits and risks of a measles vaccination programme and justify whether the government should try to vaccinate as many children as possible.

   [6 marks]

   Total for question 4: 12 marks

End of questions