16.1.2B9. Organisms and their Environment
Endangered Species — Combined Science 0653 - Biology Revision Notes & Topical Questions
5 min read 6 parts Lesson 6 of 6 Unit quiz
Section 1 of 6What is an endangered species?
Definition
- Definition An endangered species is one that is at risk of becoming extinct.
- Its population has usually fallen below a critical level.
Low genetic variation
- Low genetic variation A small population has little genetic variation, so its members are all very similar.
- If the environment changes, none of them may have the adaptations needed to survive, and the whole species could die out quickly.
Section 2 of 6Causes of a species becoming endangered
Why numbers fall
Hunting
- Hunting Animals killed for meat, fur, horn or ivory can be reduced faster than they can reproduce.
Climate change
- Climate change Changing temperatures and rainfall alter habitats, and some species cannot adapt or move in time.
Pollution
- Pollution Chemicals and waste can poison organisms or damage the places they live.
Loss of habitat
- Loss of habitat Clearing land for farming, building and industry removes shelter and food supplies.
Non-native species
- Non-native species Introduced species may outcompete native species for food and space, or prey on them.
Section 3 of 6Conservation measures
| Measure | How it helps |
|---|---|
| Education programmes | People learn why species matter, so they are more likely to support protection. |
| Captive breeding programmes | Animals are bred in zoos or reserves to build up numbers, and some may be released into the wild. |
| Monitoring and legal protection | Populations and habitats are tracked and laws prevent hunting and damage to habitats. |
| Seed banks | Seeds of endangered plants are carefully stored so new plants can be grown in the future. |
Section 4 of 6Why conserve species?
1
Reduce extinction rates, because once a plant or animal species is lost it cannot be brought back.
2
Limit damage to food chains and food webs, which protects fragile ecosystems such as rainforests.
3
Protect future food supplies by keeping a wide range of wild relatives of crops and farm animals.
4
Maintain nutrient cycles, which depend on the many organisms in an ecosystem.
5
Preserve possible sources of future medicines and fuels, and respect the moral and cultural value many people place on wildlife.
Section 5 of 6Key terms
| Term | Meaning |
|---|---|
| Endangered species | A species at risk of becoming extinct. |
| Extinction | The permanent loss of every individual of a species. |
| Captive breeding | Breeding endangered animals in zoos or reserves to increase their numbers. |
| Seed bank | A store of seeds from plant species, kept so plants can be grown again later. |
| Non-native species | A species introduced to an area where it does not naturally live. |
| Genetic variation | The differences in genes between individuals of a species. |
Section 6 of 6Exam technique
1
Saying endangered species are already extinct. They are at risk of becoming extinct.
2
Giving only one cause. Hunting, climate change, pollution, habitat loss and non-native species are all valid.
3
Forgetting that low genetic variation makes a small population very vulnerable to change.
4
Suggesting conservation is only for animals. Seed banks protect endangered plants.
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