Cambridge IGCSE Biology practice

Paper 3 structured question: Pollution

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At a glance

Paper

Marks

Topic

Pollution

Exam-style question

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Paper 3Theory (Core)2 marks

Aquatic ecosystems can be affected by pollution from untreated sewage and excess fertilizers.

Description

Untreated sewage and excess fertilizers enter a lake, causing changes in oxygen levels and aquatic life.

a
Describe how untreated sewage affects oxygen levels in aquatic ecosystems.
Your answer
Aim for approximately 2 distinct marking points.
[2]

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Paper 3Theory (Core)3 marks

Description

Excess fertilizers run off into a pond, causing algal blooms.

a
Describe how excess fertilizers lead to oxygen depletion in aquatic ecosystems.
Your answer
Aim for approximately 3 distinct marking points.
[3]