Conservation — Cambridge IGCSE Biology
Sustainable resources, why species become endangered, and how forests, fish stocks and endangered species are conserved.
Revision notes
3 short notes, in the order of the specification. Each one in short:
A sustainable resource is a resource which is produced as rapidly as it is removed from the environment so that it does not run out. Forests are conserved by education, protected areas, quotas and replanting. Fish stocks are conserved by education, closed seasons, protected areas, controlled net types and mesh size, quotas and monitoring of populations.
An endangered species is at risk of dying out, and an extinct species has no individuals left alive. Causes include climate change, habitat destruction, hunting, overharvesting, pollution and introduced species. Endangered species are conserved by monitoring and protecting species and habitats, education, captive breeding programmes and seed banks. Artificial insemination and IVF help captive breeding.
Reasons for conservation programmes
SupplementConservation programmes maintain or increase biodiversity, reduce extinction, protect vulnerable ecosystems such as rainforests and coral reefs, and maintain ecosystem functions such as nutrient cycling and resource provision, including food, drugs, fuel and genes. When a population becomes small, genetic variation is reduced, so the species is less able to survive a new disease or a changing environment.
Exam questions
8 exam-style questions (28 marks), each with its mark scheme.
Answer the questionsFlashcards
12 cards: flip them, mark what you knew, and practise the rest.
Practise the cardsMind map
The whole of human influences on ecosystems on one page, so you can see where this subtopic fits.
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Quick check questions
Define a sustainable resource.
Show answer
One which is produced as rapidly as it is removed from the environment so that it does not run out.
Give four reasons why species become endangered or extinct.
Show answer
Any four of: climate change, habitat destruction, hunting, overharvesting, pollution, introduced species.
What is a seed bank?
Show answer
A store of seeds from rare plants, kept so that the plants can be grown again if wild populations are lost.
Supplement Why does a small population have a greater risk of dying out?
Show answer
Less genetic variation, so fewer individuals may survive disease or environmental change.
Supplement Why does a larger mesh size help conserve fish stocks?
Show answer
Young fish escape and can grow and breed.
Frequently asked questions
How can fish stocks be conserved?
Supplement Fish stocks are conserved by education, closed seasons and protected areas where fishing is banned, controlled net types and mesh size, quotas and monitoring. A larger mesh lets young fish escape so they can grow and breed. Quotas limit the catch so fish are not removed faster than they reproduce. Monitoring lets quotas be adjusted.
Why do species become endangered?
Species become endangered because of climate change, habitat destruction, hunting, overharvesting, pollution and introduced species. Habitat destruction removes food, shelter and breeding sites. Hunting and overharvesting remove organisms faster than they can be replaced. An introduced non-native species may compete with, prey on or spread disease to native species.
How do seed banks help conserve plants?
A seed bank is a store of seeds of rare plants kept at low temperature, so that plants can be grown later if the wild population dies out. It is one way of conserving endangered species, along with monitoring and protecting species and habitats, education and captive breeding programmes in zoos and reserves.
How do IVF and artificial insemination help endangered species?
Supplement Artificial insemination lets animals in different zoos breed without being moved, and helps animals that will not mate naturally. In IVF, eggs are fertilised outside the body and the embryos are placed into the female or a surrogate, producing more offspring. With both, conservationists choose parents that are not closely related, keeping genetic variation.
Why is conservation important?
Supplement Conservation is important to maintain biodiversity and reduce extinction, which is permanent. It protects vulnerable ecosystems such as rainforests and coral reefs, and keeps ecosystem functions such as nutrient cycling and the provision of food, drugs, fuel and genes. Small populations lose genetic variation, so they are less able to survive disease or change.
Written and checked against the Cambridge IGCSE Biology (0610) specification · Updated October 2026