Biology · Edexcel Paper 2
Human Impact on Ecosystems
How human activity affects ecosystems and biodiversity, including fish farming, non-indigenous (introduced) species and eutrophication, why it matters to keep biodiversity high through conservation and reforestation, and, for separate Biology, the biological factors that affect food security and how indicator species show pollution of water and air. Matches Edexcel Topic 9 statements 9.9, 9.10, 9.11 and 9.16. The first two lessons are for both Combined Science and separate Biology; the last two lessons (9.11B food security and 9.16B indicator species) are for separate Biology only. There is no Higher tier only content in this chapter.
Lessons
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1
Fish Farming, Introduced Species and Eutrophication
People change ecosystems every time they farm, fish, build or pollute. This lesson is for both Combined Science and separate Biology. It looks at three human…
10 terms -
2
The Benefits of Maintaining Biodiversity
Why should we care about a beetle, a fungus or a rainforest tree that nobody eats? This lesson is for both Combined Science and separate Biology. It explains…
10 terms -
Knowledge organiser
The whole chapter on a page or two of A4 — to revise from on screen or print.
Key terms in this chapter
All 20, gathered from every lesson.
- Biodiversity
- The variety of different species of organisms in an ecosystem or on the whole Earth.
- Fish farming
- Rearing fish in cages, tanks or ponds, feeding them and harvesting them for food.
- Non-indigenous species
- A species that has been introduced to an area where it does not naturally live.
- Indigenous species
- A species that is native to an area and naturally lives there.
- Eutrophication
- The enrichment of water with mineral ions such as nitrates and phosphates, leading to an algal bloom, a fall in oxygen and the death of aquatic life.
- Algal bloom
- A thick layer of algae on the surface of the water, caused by an excess of mineral ions.
- Fertiliser
- A substance containing minerals such as nitrates and phosphates that is added to soil to help crops grow.
- Overfishing
- Catching fish faster than they can reproduce, so that wild stocks fall.
- Biological control
- Using a living organism to reduce the numbers of a pest.
- Run-off
- Water flowing off the land, carrying fertiliser and other substances into rivers and lakes.
- Conservation
- Protecting and managing species and their habitats so that they do not become extinct.
- Extinction
- The permanent loss of a species, when the last individual has died.
- Gene pool
- All the different alleles of all the genes in a population or species.
- Captive breeding
- Breeding endangered animals in zoos or breeding centres, often to release them into the wild.
- Nature reserve
- An area of land that is protected so that its wildlife and habitats can survive.
- Reforestation
- The planting of trees on land that was once forest but has been cleared.
- Deforestation
- The clearing of large areas of forest, usually for timber, farmland or building.
- Habitat
- The place where an organism lives, which provides its food, shelter and breeding sites.
- Monoculture
- A large area in which only one crop species is grown.
- Carbon sink
- Something that takes in more carbon dioxide than it releases, such as a growing forest.