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
Cell Biology
Surface area to volume ratio and exchange surfaces
- 3 things to know
- Paper 1
Overview
Why single-celled organisms rely on their outer surface, surface area to volume ratios of cubes, why large organisms need exchange surfaces and transport systems, adaptations of the small intestine, lungs, gills, roots and leaves, and the features that make exchange effective.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
What happens to the surface area to volume ratio of an organism as it gets larger?
Key term
A cube has sides of 1 cm. What is its surface area to volume ratio?
Questions from this subtopic
Each one with the model answer underneath.
- 1
Why can a single-celled organism rely on its outer surface alone for exchange?
Model answer
It has a relatively large surface area to volume ratio, so enough molecules can move in and out to meet its needs.
- 2
What happens to the surface area to volume ratio of an organism as it gets larger?
Model answer
The ratio gets smaller, because volume increases faster than surface area.
- 3
A cube has sides of 1 cm. What is its surface area to volume ratio?
Model answer
6 to 1, from a surface area of 6 cm² and a volume of 1 cm³.
- 4
A cube has sides of 2 cm. What is its surface area to volume ratio?
Model answer
3 to 1, from a surface area of 24 cm² and a volume of 8 cm³.
- 5
A cube has sides of 3 cm. What is its surface area to volume ratio?
Model answer
2 to 1, from a surface area of 54 cm² and a volume of 27 cm³.
- 6
Explain why a large multicellular organism needs specialised exchange surfaces.
Model answer
Its surface area to volume ratio is small, so its outer surface cannot take in and remove enough substances for all its cells.
Other ways to work this
The same content, four other ways.
What is inside Levo
Six ways to work the same material.
Every question in Cell Biology, on a schedule.
Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.
Or £46 a year, about £3.83 a month. Cancel anytime.