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What is an ecosystem?
Interactions between a community of living organisms and their environment
What is the environment?
Conditions that surround any living organism
What is a population?
All the organisms of the same or closely related species in an area
What is a habitat?
Where an organism lives
What is a community?
Two or more populations of organisms
What are the levels of organisation within an ecosystem?
Producer, primary consumer, secondary consumer, tertiary consumer
What abiotic factors affect abundance and distribution of organisms?
Light intensity, temperature, water, pollutants, competition, predation
Why is interdependence important in a community?
If the population of one organism falls or rises, it can have a knock on effect on the rest of the ecosystem
What is parasitism?
The relationship between different species in which one organism lives on or in the other organism. One benefits from this while the other may be harmed
A foetus is technically a parasite, ivy is too
What is mutualism?
The relationship where two species benefit from their interactions, such as lichen - algae can synthesise food, while fungi absorbs water and minerals for the algae to use
What happens at each trophic level?
Some energy is transferred to less useful forms, so trophic level decreases in size
How does loss of energy at trophies levels Impact the number of organisms at each trophic level?
The number of organisms at each level decreases, which limits the food chain length, and means that pyramids of biomass reduce in size going up the pyramid
Positive human impacts on biodiversity
Breeding programmes help preserve endangered species, the protection and development of endangered species, reducing deforestation, reforestation, replanting hedgerows, recycling rather than dumping
Negative human impacts on biodiversity
Overuse of fertilisers can cause eutrophication and reduced biodiversity, fish farming can reduce biodiversity, introduction of non-indigenous species can reduce biodiversity, increase in fossil fuel emission has sped up climate change and global warming causing the endangerment of species, hunting of species until extinction
What impacts food security?
Increasing human population, increasing animal farming and increased meat and fish consumption, impact of pathogens and pests, environmental change caused by humans, sustainability issues
What processes are in the water cycle?
Evaporation, condensation, transportation, precipitation, surface runoff, infiltration, transpiration
Why is the water cycle important?
All living organisms need water
How is potable (drinkable) water produced in areas of drought?
Desalination or reverse osmosis
What processes are in the carbon cycle?
Photosynthesis, respiration, combustion, decomposition
Why is the carbon cycle important?
Most living cells contain carbon
How are nitrates available for plant uptake from the use of fertilisers?
They provide a source of nitrate to increase crop yield
How are nitrates available for plant uptake from crop rotation?
Growing crops such as peas or beans can form nitrates as they have nitrogen fixing bacteria in their roots. This increases the nitrate content in soil, which can then be used by plants grown next time
How are nitrates available for plant uptake from bacteria in the nitrogen cycle?
Decomposes break down the bodies of dead organisms. This means nitrogen is returned to the soil as ammonia. Nitrogen is returned to the soil as ammonia. Nitrifying bacteria break down the ammonia into nitrates
How are organisms used to assess levels of pollution in water?
Bloodworms and sludgeworms are examples of pollution indicator species
Bloodworms indicate moderate pollution
Sludgeworms indicate high pollution
How are freshwater shrimps and stoneflies used to assess levels of pollution in water?
The presence of stoneflies indicates clean water
Freshwater shrimps indicate some pollution
How are lichen and black spot fungi used to assess levels of pollution in the air?
Leafy lichen indicate clean air
Blackspot fungi indicate polluted air
How does temperature affect the rate of decomposition?
Lower temperatures means less active organisms so there is a low rate of decomposition - food is preserved
Higher temperatures means more active organisms so a high rate of decomposition in composting
Too high temperatures kill bacteria so no decomposition tales place
How does water content affect rate of decomposition?
Having little to no water means less decomposition takes place as decomposers can’t survive - food is preserved
Having more water means more decomposition takes place as enzymes are secreted. Composting happens
How does oxygen affect rate of decomposition?
Having less to no oxygen present means little decomposition takes place as decomposers need oxygen to survive - food is preserved
Having more oxygen present means more decomposition takes place in composting
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