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CAIE IGCSE Biology 20.3 Pollution Questions

Practise pollution questions by interpreting sewage and fertiliser effects, tracing plastic hazards and explaining greenhouse gases or eutrophication.

Syllabus
2026–2028
Course
Biology 0610

Exam points

  • interpret sewage or fertiliser data using bacteria, nitrate, oxygen and fish evidence
  • trace non-biodegradable plastics through marine or terrestrial food chains
  • sequence eutrophication from nitrate ions to producer growth, decay and oxygen loss

Covered syllabus points

20.3.1—Effects of untreated sewage and excess20.3.2—Effects of non-biodegradable plastics20.3.3—Sources and effects of pollution20.3.4—Process of eutrophication of water

Question 1

[Maximum number: 2]

Phytoplankton are producers found in the ocean. Phytoplankton absorb microplastics into their cells.

Fig. 6.2 shows a shearwater bird.

Shearwater birds feed on fish in the ocean.

Fig. 6.2

Fig. 6.2

Suggest how microplastics can end up in consumers such as shearwater birds.

Question 2

[Maximum number: 3]

Fig. 6.1 shows part of the carbon cycle in the ocean.

Fig. 6.1 (not to scale)

Fig. 6.1 (not to scale)

Describe the effect on the environment of additional carbon dioxide in the atmosphere.

Question 3

[Maximum number: 4]

Researchers investigated the effect of adding cattle manure (cattle faeces) to fields where snap bean plants, Phaseolus vulgaris, were grown. Cattle manure contains some protein.

Snap bean plants are legumes which have root nodules that contain nitrogen-fixing bacteria.

Fig. 4.1 shows some root nodules.

Fig. 4.1

Fig. 4.1

When large quantities of manure are put on fields it can lead to eutrophication of streams and rivers. This can lead to the death of fish.

Describe how eutrophication of streams and rivers can lead to the death of fish.

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