CAIE IGCSE Biology 20.3.1 Effects of Untreated Sewage and Excess Questions
Practise explaining how untreated sewage and excess fertiliser alter nutrients, dissolved oxygen and aquatic populations.
- Syllabus
- 2026–2028
- Course
- Biology 0610
Exam points
- explain how excess fertiliser adds mineral ions that cause eutrophication and increased aquatic-plant growth
- explain how sewage organic matter increases bacterial respiration, reducing dissolved oxygen and harming aquatic animals
- interpret river nitrate or oxygen readings and indicator-organism distributions to locate pollution inputs
CAIE IGCSE Biology 20.3.1 Effects of Untreated Sewage and Excess Questions question 1
The bloodworm is an organism that is found in heavily polluted water.
The diagram shows where raw sewage flows into a river.
Where would there be fewest bloodworms?
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