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
Homeostasis and Response
Homeostasis
- 3 things to know
- Paper 2
Overview
What homeostasis is and why cells and enzymes need stable conditions, the control of blood glucose, body temperature and water level, nervous and hormonal responses, and the receptors, coordination centres and effectors of every control system.
What you need to know
Answer each one before you reveal it.
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Key term
Changes that homeostasis responds to come from two sources. What are they?
Key term
Why does a stable internal environment matter to enzymes?
Questions from this subtopic
Each one with the model answer underneath.
- 1
What is meant by homeostasis?
Model answer
The regulation of the internal conditions of a cell or organism so that they stay at the optimum for its functions.
- 2
Changes that homeostasis responds to come from two sources. What are they?
Model answer
Changes inside the body itself and changes in the external environment.
- 3
Why must an organism hold its internal conditions within narrow limits?
Model answer
Its cells only work properly over a narrow range of conditions, so conditions have to be kept close to the optimum.
- 4
Why does a stable internal environment matter to enzymes?
Model answer
Enzymes only work at their fastest within a narrow range of temperature and pH, and homeostasis keeps conditions there.
- 5
Apart from enzyme action, what else does homeostasis keep at its optimum?
Model answer
All the other functions carried out by the cells of the body.
- 6
Name the three internal conditions controlled in the human body.
Model answer
Blood glucose concentration, body temperature and the water level of the body.
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