Human Influences on the Environment Flashcards
All 21 cards in this deck
What is biodiversity?
The variety of different species (and genetic variation) in an ecosystem or on Earth.
Why does high biodiversity make an ecosystem more stable?
Species depend on each other for food, shelter and maintaining the environment, so loss of one species has less effect when many alternatives exist.
Give two ways fish farming reduces biodiversity in surrounding waters.
Waste food and faeces cause eutrophication, and parasites/diseases (e.g. sea lice) spread to wild fish.
Name two controls used in fish farming to limit its impact on wild species.
Keeping fish in mesh cages/nets to exclude predators and stop escapes, and treating fish with pesticides or antibiotics to control parasites and disease.
What is a non-indigenous (invasive) species?
A species introduced to an area where it does not naturally occur, either deliberately or accidentally.
Name three ways a non-indigenous species can reduce the biodiversity of an ecosystem.
Out-competing native species for resources, preying on native species, and bringing new diseases/parasites that natives have no resistance to.
What are the steps of eutrophication?
e.g. fertiliser washed from a field into a river
- Fertiliser run-off adds nitrates to the water.
- Algae grow rapidly (algal bloom) and block sunlight, so plants below die.
- Decomposing microorganisms respire and use up the oxygen, so fish and other aquatic animals die.
True or false? In eutrophication, the algae themselves use up all the oxygen that kills the fish.
False. Oxygen is mainly used up by the microorganisms (decomposers) respiring as they decompose the dead plants and algae.
What is an indicator species?
A species whose presence, absence or abundance indicates the level of pollution in an environment.
Which two named invertebrates indicate polluted water with low oxygen?
Bloodworms and sludgeworms.
Which two named invertebrates indicate clean, well-oxygenated water?
Freshwater shrimps and stonefly (nymphs).
Which organisms are used as indicators of air quality?
Lichens (different species tolerate different sulfur dioxide levels) and blackspot fungus on roses.
True or false? Lots of lichen species growing on trees indicates high levels of sulfur dioxide in the air.
False. A wide variety of lichens indicates clean air; polluted air leaves few or no lichen species.
Give one advantage and one limitation of using indicator species instead of chemical measurement of pollution.
Advantage: cheap, quick and shows the long-term effect of pollution on living things. Limitation: only gives a rough estimate, not the actual concentration of the pollutant, and other factors (e.g. temperature, disease) can affect the species.
How do you use indicator species data to judge water pollution?
e.g. a stream sample contains many sludgeworms and no stonefly nymphs
- Identify which indicator species are present and absent.
- Match them to their pollution tolerance: sludgeworms tolerate pollution, stonefly need clean water.
- Conclude the pollution level: the stream is polluted with low oxygen.
What is conservation?
Protecting and managing a species or habitat so that populations are maintained or increased.
What is the purpose of a captive breeding programme?
To increase the numbers of an endangered species in captivity (keeping genetic diversity) so individuals can be released back into the wild.
What is reforestation?
Replanting trees in areas where forest has been cut down or destroyed.
Give two benefits of reforestation.
It restores habitats so biodiversity increases, and it removes carbon dioxide from the atmosphere by photosynthesis, reducing global warming.
Give three human benefits of maintaining global biodiversity.
Sources of food and new medicines, protection of food chains and ecosystem services (e.g. pollination, climate regulation), and income from ecotourism.
True or false? A conservation scheme that increases one endangered species can also benefit other species in the same habitat.
True. Protecting the habitat maintains food chains and shelter for other organisms, raising overall biodiversity.