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
Plant hormones and their uses
- 3 things to know
- Paper 2
Overview
Phototropism and gravitropism, how auxin makes shoots bend towards light and roots grow downwards, and investigating the effects of light and gravity on seedlings, with control variables and labelled drawings.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
What is gravitropism?
Key term
Explain how a root turns downwards when a seed germinates on its side.
Questions from this subtopic
Each one with the model answer underneath.
- 1
What is phototropism?
Model answer
The growth of a plant in response to the direction of light.
- 2
What is gravitropism?
Model answer
The growth of a plant in response to gravity.
- 3
Which plant hormone controls the growth of shoots and roots?
Model answer
Auxin.
- 4
Explain why a shoot lit from one side bends towards the light.
Model answer
Auxin builds up on the shaded side, where it makes the cells grow longer, so that side grows faster and the shoot curves towards the light.
- 5
Explain how a root turns downwards when a seed germinates on its side.
Model answer
Auxin gathers on the lower side of the root, where it slows growth, so the upper side grows faster and the root bends down.
- 6
Why is it an advantage to a plant that its roots grow downwards?
Model answer
The roots grow into the soil, where they anchor the plant and absorb water and mineral ions.
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