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Detailed notes on Human Influences on Ecosystems for Cambridge IGCSE Biology, covering key concepts, explanations, examples, and exam-focused revision points.
Saving species and ecosystems. Cambridge wants the methods (parks, breeding, seeds, sustainable use) and the reasons.
Mapped to the Cambridge IGCSE 0610 syllabus (2026-2028).
Medical, ecological, ethical, economic — all reasons to protect biodiversity.
1. Medical reasons.
2. Ecological reasons.
3. Ethical / cultural reasons.
4. Economic reasons.
Worked qualitative. Why is the LOSS OF AMAZON RAINFOREST a global concern, not just a Brazilian one?
Cambridge tip. When asked why conservation, give 3-4 different categories of reason. Cambridge marks variety.
Protected areas, captive breeding, seed banks, sustainable use, legislation.
1. Protected areas.
2. Captive breeding.
3. Seed banks.
4. Sustainable use of resources.
5. Legislation.
6. Education + ecotourism.
Worked qualitative. Why have CHINESE PANDAS recovered (slowly) under conservation?
Cambridge tip. When asked methods, give 4-5 different ones with brief explanation. Cambridge marks each.
Use without destroying. Fishing quotas, selective logging, replanting.
Sustainable fishing.
Methods:
Sustainable forestry.
Methods:
Sustainable agriculture.
Worked qualitative. Why did NORTH ATLANTIC COD POPULATIONS COLLAPSE in the 1990s?
Cambridge tip. Always link the METHOD to its EFFECT on the population. 'Mesh size' alone = 0; 'large mesh size lets young fish escape to reach breeding age' = 1.
Verbatim phrases and definitions Cambridge mark schemes credit.
Conservation appears Paper 4 (5-7 marks: methods + reasons). Examiner reports flag students giving methods without explaining HOW they help.
Sources: Cambridge IGCSE Biology 0610 syllabus 2026-2028 (20.4); 0610/42 Oct/Nov 2024 — Q22 (conservation); 0610 Examiner Reports 2022-2024. Last reviewed 2026-05-07.
Step-by-step solutions to past-paper-style questions on conservation, written exactly the way a tutor would explain them at the board.
Question
State what is meant by a sustainable resource, and name two resources that can be managed sustainably.
Step-by-step solution
Step 1
A sustainable resource is one that is produced as rapidly as it is removed from the environment, so it does not run out.
Step 2
Example 1: forests (trees can be replanted as they are cut down).
Step 3
Example 2: fish stocks (fish can reproduce to replace those that are caught, if not overfished).
Answer
A sustainable resource is produced as fast as it is used, so it does not run out. Examples: forests and fish stocks.
Question
State four reasons why a species might become endangered or extinct.
Step-by-step solution
Step 1
Habitat destruction — the species loses where it lives.
Step 2
Hunting and overharvesting — too many are killed or taken.
Step 3
Pollution — poisons or changes the environment.
Step 4
Climate change and introduced (foreign) species — change the conditions or outcompete/prey on the species.
Answer
Habitat destruction, hunting/overharvesting, pollution, climate change and introduced species.
Examiner tip
The syllabus lists: climate change, habitat destruction, hunting, overharvesting, pollution and introduced species.
Question
Describe four ways in which endangered species can be conserved.
Step-by-step solution
Step 1
Monitoring and protecting the species and its habitat — for example, in nature reserves where the species is safe.
Step 2
Education — making people aware of the species and why it should be protected.
Step 3
Captive breeding programmes — breeding the species in zoos or sanctuaries, then releasing them into the wild.
Step 4
Seed banks — storing seeds of plant species as a backup, so they are not lost.
Answer
Monitoring and protecting species and habitats, education, captive breeding programmes, and seed banks.
Question
Describe four ways fish stocks can be conserved so that they are not overfished.
Step-by-step solution
Step 1
Quotas — limits on the mass or number of fish that may be caught, so enough are left to breed.
Step 2
Controlled net types and mesh size — using nets with a larger mesh lets the young fish escape to grow and reproduce.
Step 3
Closed seasons — no fishing during the breeding season, so the fish can reproduce undisturbed.
Step 4
Protected areas and monitoring (plus education) — no-fishing zones where fish are safe, with monitoring of stocks to set the rules.
Answer
Quotas, larger mesh sizes (young fish escape), closed seasons, protected areas and monitoring (with education).
Question
Explain how captive breeding helps endangered animals, including the use of artificial insemination (AI) and in vitro fertilisation (IVF), and why a very small population is at risk.
Step-by-step solution
Step 1
In a captive breeding programme, animals are bred in zoos or sanctuaries, in safe conditions, so their numbers can increase, with the aim of releasing them into the wild.
Step 2
Artificial insemination (AI) can be used to fertilise a female with sperm from a chosen male, even if the animals are kept apart.
Step 3
In vitro fertilisation (IVF) can be used to fertilise eggs outside the body and implant the embryos, helping rare animals to reproduce.
Step 4
A very small population has reduced genetic variation (fewer different alleles), so it is less able to adapt to disease or changes in the environment, making it more likely to become extinct.
Answer
Captive breeding increases numbers in safe conditions for release; AI and IVF help rare animals reproduce. A small population has reduced genetic variation, so it is less able to adapt and is at greater risk of extinction.
Examiner tip
AI and IVF in captive breeding, and the risk to a small population (reduced genetic variation), are Supplement content (20.4).
Question
Explain the reasons for carrying out conservation programmes.
Step-by-step solution
Step 1
To maintain or increase biodiversity and reduce extinction, so that species are not lost.
Step 2
To protect vulnerable ecosystems that could otherwise be damaged or destroyed.
Step 3
To maintain ecosystem functions, such as nutrient cycling, which keep the environment working.
Step 4
To keep the resources that species provide — food, drugs (medicines), fuel and useful genes that may be valuable now or in the future.
Answer
To maintain/increase biodiversity and reduce extinction; to protect vulnerable ecosystems; to maintain ecosystem functions (e.g. nutrient cycling); and to keep resources such as food, drugs, fuel and genes.
Examiner tip
These are the syllabus reasons (20.4): biodiversity, reducing extinction, protecting ecosystems, ecosystem functions including nutrient cycling and resources (food, drugs, fuel, genes).
High-scoring sample answers for conservation on the Cambridge IGCSE 0610 paper, with examiner-style notes mapping each response to the mark scheme and assessment objectives.
State what is meant by a sustainable resource. (1 mark)
Model answer
A sustainable resource is one that is produced as rapidly as it is removed from the environment, so that it does not run out.
Why this scores
One mark for 'produced as fast as it is used / does not run out'.
State two reasons why a species might become endangered. (2 marks)
Model answer
Any two of: habitat destruction, hunting or overharvesting, pollution, climate change, or the introduction of a foreign (introduced) species.
Why this scores
Two distinct reasons from the syllabus list.
Describe three ways in which an endangered species can be conserved. (3 marks)
Model answer
By monitoring and protecting the species and its habitat (for example in a nature reserve); by educating people about it and why it should be protected; and by using a captive breeding programme to breed the species and release it into the wild. (Storing seeds in a seed bank is also accepted for plants.)
Why this scores
Three marks from: monitoring/protecting species and habitats; education; captive breeding; seed banks.
Explain how fish stocks can be conserved so that they are used sustainably. (4 marks)
Model answer
Quotas limit the mass of fish that may be caught, so that enough fish are left to breed and replace those caught. Using nets with a larger mesh size allows the young fish to escape and grow to breeding age. Closed seasons stop fishing during the breeding season, so the fish can reproduce undisturbed. Protected areas (no-fishing zones) and the monitoring of stocks also help, so that the number of fish caught never exceeds the number that can be replaced.
Why this scores
Four marks from: quotas; larger mesh size (young escape); closed seasons; protected areas/monitoring — each linked to allowing the fish to breed/replace.
Explain the reasons for carrying out conservation programmes. (5 marks)
Model answer
Conservation programmes aim to maintain or increase biodiversity (the number of different species) and to reduce extinction, so that species are not lost forever. They aim to protect vulnerable ecosystems from being damaged or destroyed, and to maintain the functions of ecosystems, such as nutrient cycling, which keep the environment healthy. They also aim to preserve the resources that living organisms provide — such as food, drugs (medicines), fuel and useful genes — which are valuable to humans now and may be even more valuable in the future.
Why this scores
Five marks: maintain/increase biodiversity; reduce extinction; protect vulnerable ecosystems; maintain ecosystem functions (nutrient cycling); preserve resources (food/drugs/fuel/genes).
Explain how both forests and fish stocks can be conserved so that they remain sustainable resources. (6 marks)
Model answer
A resource is sustainable if it is produced as fast as it is used, so that it does not run out. Forests can be conserved by education, so people understand the need to protect them; by creating protected areas where trees cannot be cut down; by setting quotas that limit how many trees may be felled; and by replanting trees to replace those that are cut down, so that the forest is maintained. Fish stocks can be conserved by education about overfishing; by setting quotas on the mass of fish that may be caught, so enough are left to breed; by using controlled net types and a larger mesh size, so that young fish escape to grow and reproduce; by having closed seasons when no fishing is allowed during the breeding period; and by creating protected areas and monitoring the stocks. In both cases, the key idea is to take only as much as can be naturally replaced, so the resource continues into the future.
Why this scores
Up to 6 marks: forests — education, protected areas, quotas, replanting; fish — education, quotas, mesh size (young escape), closed seasons, protected areas, monitoring; the principle of taking only what can be replaced.
Definitions to memorise and the exact keywords mark schemes credit for conservation answers — sharpened from recent examiner reports for the 2026 0610 sitting.
The protection and management of species and ecosystems to maintain biodiversity for the future.
A resource that is produced as rapidly as it is removed from the environment, so it does not run out.
An area (such as a national park or marine reserve) where human activity is restricted to protect the habitat and species.
A store of seeds of plant species, kept as a backup so that the species are not lost.
Breeding endangered animals in zoos or sanctuaries (sometimes using AI or IVF), often to release them into the wild.
The traps other students keep falling into on conservation questions — taken from recent Cambridge IGCSE 0610 examiner reports and mark schemes — and how to avoid them.
Why it happens
Successful breeding in zoos sounds reassuring.
How to avoid it
Captive breeding only works long-term if there is a HABITAT to release the animals back into, so habitat protection is also essential.
Why it happens
It sounds like total protection.
How to avoid it
Conservation can include SUSTAINABLE use — taking only as much as can be naturally replaced (e.g. quotas, replanting, closed seasons).
Why it happens
The species is not yet extinct.
How to avoid it
A very small population has REDUCED genetic variation, so it is less able to adapt to disease or change — making extinction more likely.
The things students keep getting wrong in this sub-topic, answered.