Human Influences on the Environment Flashcards
All 12 cards in this deck
What is meant by biodiversity?
The variety (number) of different species living in an ecosystem, or on Earth as a whole.
What are the steps of eutrophication?
e.g. fertiliser washed off a field into a lake
- Run-off / leaching of fertiliser causes a build-up of nitrates (and phosphates) in the water.
- This causes an overgrowth of algae, which blocks sunlight from plants in the water, so they cannot photosynthesise and die.
- Decomposers (microorganisms) respire as they break down the dead plants, so oxygen concentration falls and fish and other animals die.
Give two ways fish farming can reduce biodiversity in the surrounding water.
Waste and uneaten food cause eutrophication; parasites and disease spread from the farm to wild fish.
Give one positive impact of fish farming on biodiversity.
It reduces pressure on wild fish stocks, so wild populations can recover.
How can introducing a non-indigenous species reduce biodiversity?
e.g. signal crayfish introduced into English rivers
It outcompetes native species for food and habitat, preys on them, and brings disease they have no resistance to — so native species' numbers fall. e.g. white-clawed crayfish numbers decrease.
What term describes methods used to increase the population of an endangered species, such as the white-clawed crayfish?
Conservation.
Give two methods used in animal conservation projects to increase numbers of endangered species.
Controlled breeding programmes and maintaining (protecting) habitats; also reduction in poaching, allowing re-introduction into the wild.
Give two benefits to an ecosystem of conserving animal species.
It maintains the food web and maintains genetic diversity.
How does reforestation affect the composition of the air?
More photosynthesis removes carbon dioxide and releases oxygen, reducing greenhouse gases and global warming.
Give two benefits of reforestation other than changing the composition of the air.
It provides habitats, increasing biodiversity; trees take up water from the soil, preventing erosion and reducing flooding.
True or false? Income from zoos, animal parks and ecotourism can be used to fund conservation projects.
True. Generating income in this way helps pay for conservation of endangered species.
What is a non-indigenous species?
A species that does not naturally live in an area but has been brought there by humans, either on purpose (e.g. for food) or by accident (e.g. carried on ships).