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 biotechnology
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 reproductionContraceptionPlant hormones and their uses
Infection and Response
Inheritance, Variation and Evolution
Topic overviewSexual and asexual reproductionMeiosisAdvantages and disadvantages of sexual and asexual reproductionDNA and the genomeDNA as a polymer of four nucleotidesGenetic 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
Farming techniques and sustainable fisheries
- 2 things to know
- Paper 2
Overview
Improving 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.
What you need to know
Answer each one before you reveal it.
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Key term
Explain why keeping animals in a heated barn increases their growth.
Questions from this subtopic
Each one with the model answer underneath.
- 1
How can the efficiency of food production from farm animals be improved?
Model answer
By restricting the energy the animals transfer to their surroundings, limiting their movement and controlling the temperature around them.
- 2
Explain why limiting an animal's movement increases the mass of meat obtained from its food.
Model answer
Less glucose is used in respiration for muscle contraction, so more of the food is converted into body mass.
- 3
Explain why keeping animals in a heated barn increases their growth.
Model answer
Less energy is transferred to the surroundings as heat, so less food has to be respired to keep warm and more is used for growth.
- 4
Explain why fish in a fish farm are kept in cages.
Model answer
Their movement is limited and predators are kept out, so more of their food is converted into biomass.
- 5
Explain why free-range chickens usually need more food per kilogram of meat than housed chickens.
Model answer
They move about more and lose more heat to the surroundings, so more of their food is used in respiration rather than growth.
- 6
Why are some farm animals fed on high protein food?
Model answer
The protein supplies the amino acids used to build new tissue, so the animals grow faster.
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