General overview (ecosystems and material cycles)

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