Key term
AQA GCSE Combined Science Biology 8464
Bioenergetics
Cell Biology
Topic overviewEukaryotes and prokaryotesAnimal and plant cellsCell specialisation and differentiationMicroscopyChromosomes, 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 cycledWaste management and biodiversityLand use, deforestation and global warmingMaintaining biodiversity
Homeostasis and Response
Infection and Response
Inheritance, Variation and Evolution
Topic overviewSexual and asexual reproductionMeiosisDNA and the genomeGenetic 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 processEvidence 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
Inheritance, Variation and Evolution
Variation
- 3 things to know
- Biology Paper 2
Overview
Variation caused by genes, the environment or both, why siblings and cloned plants differ, extensive genetic variation arising from mutations, how few variants affect the phenotype, and how a new phenotype suited to a changed environment can spread quickly.
What you need to know
Answer each one before you reveal it.
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Key term
Give the three possible causes of variation between individuals.
Key term
Give an example of a characteristic that is caused by genes alone.
Questions from this subtopic
Each one with the model answer underneath.
- 1
What is meant by variation?
Model answer
The differences in the characteristics of the individuals in a population.
- 2
Give the three possible causes of variation between individuals.
Model answer
The genes they have inherited, the conditions in which they developed, and a combination of the two.
- 3
Give an example of a characteristic that is caused by genes alone.
Model answer
Natural eye colour.
- 4
Give an example of variation caused by the environment.
Model answer
A plant grown in dim light is taller and paler than a plant of the same variety grown in bright light.
- 5
Give a characteristic influenced by both genes and the environment.
Model answer
Body mass, which depends on inherited genes and also on diet and exercise.
- 6
Why do the offspring of the same two parents differ from one another?
Model answer
Each inherits a different mixture of the parents' genes, and they may also develop in different conditions.
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