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 biotechnologyImpact of environmental change
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 reproductionContraceptionThe use of hormones to treat infertilityNegative feedbackPlant hormones and their uses
Infection and Response
Topic overviewCommunicable (infectious) diseasesViral diseasesBacterial diseasesFungal and protist diseasesHuman defence systemsVaccinationAntibiotics and painkillersDiscovery and development of drugsProducing monoclonal antibodiesUses of monoclonal antibodiesDetection and identification of plant diseasesPlant defence responses
Inheritance, Variation and Evolution
Topic overviewSexual and asexual reproductionMeiosisAdvantages and disadvantages of sexual and asexual reproductionDNA and the genomeDNA as a polymer of four nucleotidesProtein synthesis and complementary base pairingMutations, protein shape and non-coding DNAGenetic 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
Organisation
The heart, the lungs and double circulation
- 3 things to know
- Paper 1
Overview
Gas exchange in the alveoli and how the lungs are adapted for it, the path of blood through the four chambers, the double circulatory system, the ventricles, aorta, vena cava and pulmonary vessels, the coronary arteries, and the route air takes into the lungs.
What you need to know
Answer each one before you reveal it.
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Key term
Describe the path blood takes through the four chambers of the heart, starting from the body.
Key term
What is a double circulatory system?
Questions from this subtopic
Each one with the model answer underneath.
- 1
Name the two gases exchanged in the lungs and state the direction each one moves.
Model answer
Oxygen moves from the air in the alveoli into the blood, and carbon dioxide moves from the blood into the alveoli.
- 2
Give three ways in which the lungs are adapted for efficient gaseous exchange.
Model answer
They have a very large surface area of alveoli, walls only one cell thick, and a rich supply of blood.
- 3
Explain why the walls of the alveoli are only one cell thick.
Model answer
So that the distance gases must diffuse between the air and the blood is as short as possible.
- 4
Explain how breathing helps to keep the rate of gas exchange in the lungs high.
Model answer
It replaces the air in the alveoli, so a steep concentration gradient for oxygen and carbon dioxide is maintained.
- 5
Describe the path blood takes through the four chambers of the heart, starting from the body.
Model answer
It enters the right atrium, passes into the right ventricle and out to the lungs, returns to the left atrium, then passes into the left ventricle and out to the body.
- 6
What is a double circulatory system?
Model answer
One in which blood passes through the heart twice for each complete circuit of the body.
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