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neurologyYou need to know

• The levels of organisation in an ecosystem are organism, population, community, ecosystem and biosphere.
• A population is all the organisms of one species living in the same habitat at the same time.
• A community is all the populations of different species living and interacting in the same habitat.
• An ecosystem is a community of organisms interacting with each other and with the abiotic factors in their environment.
• Interdependence means species in a community depend on each other for resources such as food, shelter, pollination, seed dispersal and nutrient cycling.
• Animals compete for food, mates and territory, while plants compete for light, water, mineral ions and space.
• Biotic factors are living factors that affect a community, such as predators, prey, pathogens, competitors and food availability.
• Abiotic factors are non-living factors that affect a community, such as light intensity, temperature, moisture level, soil pH, oxygen concentration, carbon dioxide concentration and mineral ion availability.
• A change in a biotic or abiotic factor can change the size and distribution of populations in a community.
• An adaptation is a feature that helps an organism survive and reproduce in its environment.
• Structural adaptations are physical features of an organism, behavioural adaptations are actions an organism takes, and functional adaptations are internal biological processes.
• Extremophiles are organisms that live in extreme conditions, such as very high temperatures, high salt concentrations or high pressures.
• Photosynthetic organisms, such as plants and algae, are producers because they use light energy to make glucose and produce biomass.
• A food chain shows feeding relationships using arrows that show the transfer of biomass from food to feeder.
• A food web shows many connected food chains and is a more realistic model of feeding relationships in a community.
• Predator and prey populations often rise and fall in cycles because more prey can support more predators, but more predators then reduce prey numbers.
• A quadrat is a square frame used to sample the abundance or percentage cover of organisms in a habitat.
• A transect is a line placed across a habitat to measure how the distribution of organisms changes with distance or across an environmental gradient.
• Materials such as water, carbon and mineral ions cycle between the biotic and abiotic parts of ecosystems.
• Biodiversity is the variety of different species living in an ecosystem, and high biodiversity helps ecosystems stay stable when conditions change.

• Interpret food chains and food webs by identifying producers, consumers, predators, prey and the direction of biomass transfer.
• Construct a food chain or food web from ecological information, using arrows from the organism being eaten to the organism that eats it.
• Explain the effect of changing a biotic or abiotic factor by linking the change to competition, survival, reproduction and population size.
• Use quadrats to estimate abundance by placing them randomly, counting organisms or percentage cover, and calculating a mean.
• Use a transect to investigate distribution by placing quadrats at regular intervals along a line and recording how abundance changes with distance.
• Calculate the mean, median and mode from ecological data, selecting the correct average for the question.
• Plot ecological data on an appropriate graph, choosing suitable axes, scales, units and plotting points accurately.
• Describe predator-prey cycles from a graph by linking rises and falls in predator numbers to earlier changes in prey numbers.
• Explain how microorganisms recycle materials by breaking down dead organisms and waste, releasing mineral ions and carbon compounds back into the ecosystem.
• Evaluate methods used to reduce biodiversity loss, such as breeding programmes, habitat protection, reducing deforestation, recycling, and reducing pollution.