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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 a habitat, and a community is all the populations of different species living together in a habitat.
• An ecosystem is the interaction of a community of living organisms with the abiotic factors of their environment.
• Biotic factors are living factors, including food availability, predators, pathogens and competition from other species.
• Abiotic factors are non-living environmental factors, including light intensity, temperature, moisture level, soil pH, wind intensity, oxygen concentration and carbon dioxide concentration.
• Animals often compete for food, mates and territory, while plants often compete for light, water, mineral ions and space.
• Interdependence means species in a community depend on each other for resources such as food, shelter, pollination and seed dispersal, so a change in one population can affect other populations.
• An adaptation is a feature that helps an organism survive and reproduce in its natural environment.
• Structural adaptations are physical features, behavioural adaptations are actions, and functional adaptations are internal processes that improve survival or reproduction.
• Extremophiles are organisms adapted to live in extreme environments, such as very high temperatures, high salt concentrations or high pressure.
• Photosynthetic organisms such as plants and algae are producers because they use light energy to make glucose, which becomes biomass at the start of most food chains.
• A food chain shows feeding relationships and energy transfer, with arrows pointing from the organism being eaten to the organism that eats it.
• Predator and prey populations often rise and fall in cycles because more prey can support more predators, but more predators reduce prey numbers, which later reduces predator numbers.
• Materials such as water, carbon and mineral ions cycle between the biotic components and abiotic components of an ecosystem.
• The water cycle is important because living organisms need water for chemical reactions, transport of substances and maintaining cells and tissues.
• Microorganisms decompose dead organisms and waste, releasing mineral ions and carbon compounds back into the environment for reuse by plants and other organisms.
• Biodiversity is the variety of different species living in an ecosystem or on Earth.
• High biodiversity helps ecosystems remain stable because species can depend on a wide range of food sources and interactions if conditions change.
• Human activities can reduce biodiversity through pollution, deforestation, peat bog destruction, land use change, overfishing and the release of greenhouse gases.
• Global warming is the long-term rise in Earth’s mean surface temperature, mainly caused by increased greenhouse gases such as carbon dioxide and methane from human activities.

• Construct food chains and food webs from information, placing producers first and using arrows to show the direction of biomass and energy transfer.
• Interpret food chains and food webs by identifying producers, consumers, predators, prey and the likely effects of changes in one population on others.
• Use quadrats to estimate the abundance or percentage cover of organisms by placing them randomly, recording results and calculating a representative mean.
• Use a transect to investigate how the distribution of organisms changes across an environmental gradient by placing quadrats at regular intervals along a tape measure.
• Calculate mean, median and mode from ecological data, choosing the average that best represents the data set.
• Plot ecological data on suitable graphs by choosing an appropriate graph type, selecting sensible axis scales, labelling axes with units and drawing points or bars accurately.
• Explain the effect of a change in a biotic or abiotic factor on a community by linking the factor to survival, reproduction, competition and population size.
• Classify adaptations as structural, behavioural or functional, and explain how each adaptation increases survival or reproductive success in a named environment.
• Describe the stages of the carbon cycle, including photosynthesis, feeding, respiration, decomposition and combustion.
• Evaluate methods used to reduce biodiversity loss, such as breeding programmes, habitat protection, reforestation, recycling, reducing pollution and managing fishing quotas.