Who this is for: Cambridge IGCSE Biology (0610) students who want pollution — air, water and land impacts on ecosystems — to become reliable marks instead of generic “humans damage the environment” answers.
What query it owns: how to understand and revise pollution in Cambridge IGCSE Biology.
Why this is safe: this page owns the pollution revision-guide angle, while Tutopiya’s Pollution subtopic page owns the learning resource and the free Pollution quiz owns the practice.

Pollution is the release of harmful substances into the environment. Cambridge IGCSE Biology (0610) tests air pollution (including acid rain and greenhouse effects), water pollution (sewage and fertiliser runoff leading to eutrophication), and land pollution (pesticides and plastics). This guide covers the syllabus examples, causal chains examiners reward, and the question types that appear every year.

Key takeaways

• Air pollution includes sulfur dioxide and oxides of nitrogen — linked to acid rain and respiratory disease.
• Greenhouse gases (e.g. carbon dioxide, methane) trap heat and contribute to climate change.
• Water pollution from sewage and fertilisers causes eutrophication — algal bloom → oxygen depletion → fish death.
• Pesticides can bioaccumulate and harm non-target organisms.
• Exam answers must link source → process → effect on organisms.

What is pollution in Cambridge IGCSE Biology?

Pollution is the addition of substances or energy to the environment at a rate that harms living organisms or damages ecosystems. Human activities — burning fossil fuels, farming, industry and waste disposal — are major sources. The syllabus requires you to describe specific pollutants, how they enter ecosystems, and their biological effects.

Read the full notes on Tutopiya’s Pollution subtopic page before attempting questions.

The core ideas you must master

Pollution type	Source	Biological effect
Acid rain	SO₂, NOₓ from fossil fuels	Damages leaves, acidifies lakes, kills fish
Greenhouse effect	CO₂, methane	Climate change, habitat disruption
Eutrophication	Fertilisers, sewage in water	Algal bloom, deoxygenation, fish death
Pesticides	Agriculture	Bioaccumulation, harm food chains
Plastics	Waste	Ingestion, entanglement, microplastics

Eutrophication — step by step

1. Excess nitrate/phosphate enters water from fertiliser or sewage.
2. Rapid algal growth (algal bloom) on the surface.
3. Light blocked from submerged plants, which die.
4. Aerobic bacteria decompose dead matter, using dissolved oxygen.
5. Oxygen depletion kills fish and aquatic invertebrates.

Pollution in past-paper wording

Command word	What the question wants	Typical stem
Define	Precise definition	”Define eutrophication.”
Describe	Sequence of events	”Describe how fertiliser runoff affects a lake.”
Explain	Cause and effect	”Explain how acid rain affects trees.”
Suggest	Apply to scenario	”Suggest how to reduce water pollution.”
State	Short fact	”State one source of atmospheric carbon dioxide.”

Worked exam-style stems

1. “Describe the process of eutrophication.” Excess nitrates/phosphates enter water → algal bloom → light blocked → submerged plants die → bacteria decompose dead material using oxygen → oxygen levels fall → fish die. Reward: ordered steps with oxygen depletion.
2. “Explain how sulfur dioxide causes acid rain.” SO₂ dissolves in rainwater forming sulfuric acid; acid rain lowers pH of lakes and damages plant leaves. Reward: gas → acid → biological effect.
3. “Suggest two ways humans can reduce water pollution.” Any two from: treat sewage, reduce fertiliser use, buffer strips near rivers, regulate industrial discharge. Reward: practical, syllabus-linked measures.

Practise on the Pollution quiz and Human Influences topical past paper questions.

How pollution connects to the syllabus

Pollution links to Food Supply (fertilisers), Habitat Destruction and Conservation. Eutrophication ties to Nutrient Cycles. The Biology hub links all Human Influences subtopics.

Common mistakes students make

• Describing eutrophication without oxygen depletion and fish death.
• Confusing greenhouse effect with ozone depletion (syllabus focus is greenhouse gases).
• Saying pollution always kills all organisms without naming the chain of events.
• Omitting named pollutants (SO₂, nitrates, pesticides) in explain answers.
• Ignoring bioaccumulation of pesticides in food chains.

When you need more support

If pollution and eutrophication sequences keep costing marks, work through the Human Influences topical past paper questions and the Pollution quiz, then get help from a Cambridge IGCSE Biology tutor.

Frequently asked questions

What is eutrophication? Eutrophication is the enrichment of water with nitrates/phosphates, causing algal blooms, oxygen depletion and death of aquatic organisms.

How does acid rain affect ecosystems? It lowers pH of lakes and soil, harms fish and amphibians, and damages plant leaves.

What is the greenhouse effect? Greenhouse gases trap heat in the atmosphere, raising global temperatures and affecting habitats.

How do I revise pollution effectively? Learn eutrophication steps, acid rain and greenhouse chains, practise describe questions, then take the quiz.

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