Key term
AQA GCSE Biology 8461
Bioenergetics
Cell Biology
Topic overviewEukaryotes and prokaryotesAnimal and plant cellsCell specialisation and differentiationMicroscopyGrowing bacteria and aseptic techniqueCalculating bacterial growth, and testing antiseptics and antibioticsChromosomes, mitosis and the cell cycleStem cells in embryos, adults and meristemsTherapeutic cloning, its risks, and cloning plantsDiffusion and the factors affecting its rateSurface area to volume ratio and exchange surfacesOsmosisActive transport
Ecology
Topic overviewLevels of organisation in an ecosystem, and what organisms needCompetition, interdependence and stable communitiesAbiotic factorsBiotic factorsAdaptationsProducers, food chains and sampling with quadrats and transectsPredators, prey and measuring population sizeHow materials are cycledDecompositionWaste management and biodiversityLand use, deforestation and global warmingMaintaining biodiversityTrophic levels and pyramids of biomassTransfer of biomassFactors affecting food securityFarming techniques and sustainable fisheriesRole of biotechnologyImpact of environmental change
Homeostasis and Response
Topic overviewHomeostasisThe nervous system and the reflex arcThe structure of the eye and accommodationMyopia, hyperopia and how they are correctedThe brain and the control of body temperatureHuman endocrine systemInsulin, glucagon and diabetesWater and ion loss, and the production of ureaThe kidneys, ADH and treating kidney failureHormones in human reproductionContraceptionThe use of hormones to treat infertilityNegative feedbackPlant hormones and their uses
Infection and Response
Topic overviewCommunicable (infectious) diseasesViral diseasesBacterial diseasesFungal and protist diseasesHuman defence systemsVaccinationAntibiotics and painkillersDiscovery and development of drugsProducing monoclonal antibodiesUses of monoclonal antibodiesDetection and identification of plant diseasesPlant defence responses
Inheritance, Variation and Evolution
Topic overviewSexual and asexual reproductionMeiosisAdvantages and disadvantages of sexual and asexual reproductionDNA and the genomeDNA as a polymer of four nucleotidesProtein synthesis and complementary base pairingMutations, protein shape and non-coding DNAGenetic terms, dominant and recessive allelesPunnett squares, probability and genetic crossesInherited disorders and sex determinationVariationEvolutionSelective breedingWhat genetic engineering is, and what it is used forGM crops, their risks, and the steps of the processCloningDarwin, Lamarck and the acceptance of evolutionSpeciationThe understanding of geneticsEvidence for evolution, and extinctionFossilsResistant bacteriaClassification of living organisms
Organisation
Topic overviewLevels of organisation, and how enzymes workAmylase, proteases and lipasesBile, food tests and the effect of pH on amylaseThe heart, the lungs and double circulationThe pacemaker, the blood vessels and the bloodCoronary heart disease: a non-communicable diseaseHealth issuesRisk factors and causal mechanisms in diseaseSampling, correlation and interpreting risk dataCancerPlant tissues, and transpiration and its rateRoot hair cells, xylem, phloem and stomata
Ecology
- 18 subtopics
- 45 things to know
- Paper 2
What Ecology covers
Ecology is examined in Biology Paper 2. It covers levels of organisation in an ecosystem and what organisms need; competition, interdependence and stable communities; abiotic and biotic factors and adaptations; food chains, predators and prey, and sampling with quadrats and transects; how materials are cycled and decomposition; waste management, land use, deforestation, global warming and maintaining biodiversity; trophic levels, pyramids and the transfer of biomass; food security, farming techniques, sustainable fisheries and biotechnology; and the impact of environmental change.
Where it is assessed
Paper 2
Biology Paper 2: 1 hour 45 minutes, 100 marks, 50% of the GCSE.
Check the AQA specification ↗The 18 subtopics
Each one has its own page.
- Levels of organisation in an ecosystem, and what organisms needPopulation, community, habitat and ecosystem, biotic and abiotic parts, what plants and animals must obtain to survive, and competition and adaptation in rock pools, deserts and streams.Open →
- Competition, interdependence and stable communitiesWhat plants and animals compete for, with seedlings under trees and fighting deer, interdependence and what species depend on each other for, stable communities, the effects of losing bees or a single species, and reading producers and competition from tables.Open →
- Abiotic factorsThe seven abiotic factors, dissolved oxygen in water, soil pH and minerals, wind direction, and how moisture, warming, acid rain, shelter and light change a community.Open →
- Biotic factorsFood availability, new predators, new pathogens and competition as biotic factors, with red and grey squirrels, poor acorn crops, island prey, lost plant species and diseased ash trees, and interpreting population data on introduced species and disease.Open →
- AdaptationsStructural, behavioural and functional adaptations, extremophiles such as deep sea vent bacteria and their enzymes, and examples including whale blubber, camel urine, Arctic fox ears and cactus spines and stems.Open →
- Producers, food chains and sampling with quadrats and transectsProducers and biomass, why a producer starts every food chain and what the arrows mean, quadrats and transects, distribution against abundance, and the mean, median and mode of counts.Open →
- Predators, prey and measuring population sizePrimary, secondary and tertiary consumers, predators and prey and their cycling numbers, estimating a field's dandelions with random quadrats, and using a transect along a footpath.Open →
- How materials are cycledWhy materials must be recycled, the carbon cycle through photosynthesis, respiration, combustion and decomposers, the water cycle through evaporation, condensation and precipitation, and the role of microorganisms in returning carbon dioxide and mineral ions.Open →
- DecompositionHow temperature, water and oxygen set the rate of decay, compost heaps and biogas generators, and the milk decay investigation with its pH and rate calculations.Open →
- Waste management and biodiversityWhy a growing population and rising living standards produce more waste, sources of water, air and land pollution, how fertiliser, acid rain and toxic chemicals damage ecosystems, and what biodiversity is, why it makes ecosystems stable and how human activity has reduced it.Open →
- Land use, deforestation and global warmingLand lost to building, quarrying, farming and waste, peat bog destruction and the carbon dioxide it releases, tropical deforestation for cattle, rice and biofuels, carbon dioxide and methane in global warming, and its effects on species distribution and sea levels.Open →
- Maintaining biodiversityBreeding programmes, habitat protection, field margins and hedgerows, recycling and cutting deforestation and carbon dioxide emissions, negative and positive human interactions with ecosystems, and the conflicts that conservation programmes can cause.Open →
- Trophic levels and pyramids of biomassTrophic levels from producers through primary, secondary and tertiary consumers to apex predators, animals feeding at more than one level, how decomposers digest dead matter, and drawing pyramids of biomass.Open →
- Transfer of biomassThe shape of a pyramid of biomass, the 1% of light used in photosynthesis, the 10% passed between trophic levels, where biomass is lost, and efficiency calculations.Open →
- Factors affecting food securityWhat food security is, how birth rate, changing diets, pests, pathogens, drought, farming costs and conflict threaten it, sustainable food production, and why eating crops directly feeds more people than feeding them to animals.Open →
- Farming techniques and sustainable fisheriesImproving the efficiency of meat production by limiting movement and heat loss, housed and free-range animals, fish cages and high protein food, declining fish stocks, and conserving them with net mesh sizes and fishing quotas.Open →
- Role of biotechnologyCulturing microorganisms for food, making mycoprotein from Fusarium grown on glucose syrup, producing human insulin from genetically modified bacteria, genetically modified crops including golden rice, and the arguments against them.Open →
- Impact of environmental changeTemperature, water and atmospheric gases as changes that shift where a species lives, their seasonal, geographic and human causes, and evaluating a warmed river and city lichens.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
Name five programmes used to help maintain biodiversity.
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What is meant by a population in an ecosystem?
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Name four things that plants in a habitat compete with each other for.
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Name seven abiotic factors that can affect a community.
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Name four biotic factors that can affect a community.
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What is an adaptation?
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Put these in the order in which they feed in a food chain: secondary consumer, producer, tertiary consumer, primary consumer.
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Why must the materials in the living world be recycled?
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Explain why waste decays faster at 30 °C than at 5 °C.
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Give two reasons why humans now use more resources and produce more waste than ever before.
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Explain why reducing the land available to wild species reduces biodiversity.
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What is a trophic level?
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Suggest why so little of the light falling on a leaf is transferred for photosynthesis.
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Explain how an increasing birth rate threatens food security.
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Explain why limiting an animal's movement increases the mass of meat obtained from its food.
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How does modern biotechnology help to feed a growing human population?
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Name three environmental changes that can alter where a species is found.
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What is meant by a community?
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Name three things that animals commonly compete with each other for.
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Which abiotic factor matters to animals living in water but not to animals living on land?
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Explain how a new pathogen can change a community.
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Name the three types of adaptation.
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Which organisms are the producers of biomass for life on Earth?
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In the food chain grass to rabbit to stoat to buzzard, name the secondary consumer and explain your choice.
Process
Which process removes carbon dioxide from the atmosphere, and which two processes return it?
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Explain why the rate of decay slows again if the temperature rises well above the optimum.
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Explain why a rising standard of living leads to more waste.
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Why are peat bogs dug up?
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What is a breeding programme for an endangered species?
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Which organisms are found at trophic level 1?
Numbers
A field of grass contains 20 000 kg of biomass. Estimate the biomass of the cattle that this grass supports.
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Explain how changing diets in wealthier countries can threaten food security elsewhere.
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Explain why keeping animals in a heated barn increases their growth.
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Which organism is used to produce mycoprotein?
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Explain how a long-term fall in rainfall could change the distribution of trees in a region.
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List the levels of organisation in an ecosystem in order, starting with the smallest.
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Explain why seedlings growing directly under a tall tree usually grow poorly.
Evaluation
Why is the direction of the wind, as well as its strength, an abiotic factor?
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Explain how one species outcompeting another can end a population altogether.
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What is a structural adaptation?
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What is meant by biomass?
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In the food chain algae to water flea to small fish to pike, which organism is the tertiary consumer?
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Describe how the carbon in a dead leaf is returned to the atmosphere.
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Explain why biological material decays very slowly in a hot, dry desert.
Take Ecology further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Population vs Community
Population: all the organisms of one species living in the same habitat. Community: all the different species living and interacting in the same habitat.
Habitat vs Ecosystem
Habitat: the place in which an organism lives. Ecosystem: a community of living organisms interacting with the non-living parts of their environment.
Biotic factor vs Abiotic factor
Biotic factor: a living influence on a community, such as predators, pathogens or competition. Abiotic factor: a non-living condition such as light intensity, temperature or soil pH.
Questions from this topic
Each one with the model answer underneath.
- 1
What is meant by a population in an ecosystem?
Model answer
All the organisms of one species living in the same habitat at the same time.
- 2
What is meant by a community?
Model answer
All the populations of the different species that live in the same habitat and interact with each other.
- 3
List the levels of organisation in an ecosystem in order, starting with the smallest.
Model answer
Individual organism, then population, then community, then the whole ecosystem.
- 4
What is a habitat?
Model answer
The place in which an organism lives.
- 5
What is an ecosystem?
Model answer
The interaction of a community of living organisms with the non-living parts of their environment.
- 6
An ecosystem has biotic and abiotic parts. What does each of these words mean?
Model answer
Biotic parts are the living organisms; abiotic parts are the non-living physical and chemical conditions.
What is inside Levo
Six ways to work the same material.
Ecology revision questions
- What does Ecology cover in AQA GCSE Biology?
- 18 subtopics: levels of organisation in an ecosystem, and what organisms need, competition, interdependence and stable communities, abiotic factors, biotic factors, adaptations, producers, food chains and sampling with quadrats and transects, predators, prey and measuring population size, how materials are cycled, decomposition, waste management and biodiversity, land use, deforestation and global warming, maintaining biodiversity, trophic levels and pyramids of biomass, transfer of biomass, factors affecting food security, farming techniques and sustainable fisheries, role of biotechnology and impact of environmental change. Each one has its own page with questions and model answers.
- How is Ecology organised?
- By the AQA 8461 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Ecology, on a schedule.
Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.
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