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
Cell Biology
Active transport
- 3 things to know
- Paper 1
Overview
The definition of active transport and its energy supply from respiration, uptake of mineral ions by root hair cells and of sugar from the gut, and how active transport compares with diffusion and osmosis.
What you need to know
Answer each one before you reveal it.
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Key term
Explain why active transport needs a supply of energy.
Key term
Explain why mineral ions cannot be absorbed into root hair cells by diffusion.
Questions from this subtopic
Each one with the model answer underneath.
- 1
Define active transport.
Model answer
The movement of a substance from a more dilute to a more concentrated solution, against the concentration gradient.
- 2
Where does the energy for active transport come from?
Model answer
From respiration in the cell.
- 3
Explain why active transport needs a supply of energy.
Model answer
Substances are moved against the concentration gradient, which is the opposite direction to the way they would move on their own.
- 4
How do root hair cells take up mineral ions from a very dilute soil solution?
Model answer
By active transport, moving the ions in against the concentration gradient.
- 5
Explain why mineral ions cannot be absorbed into root hair cells by diffusion.
Model answer
The ions are more concentrated inside the cell than in the soil water, so diffusion would move them out instead of in.
- 6
Why do plants need to take in mineral ions?
Model answer
They are needed for healthy growth.
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