Key term
CCEA A-Level Biology 1010
Biological Molecules
Topic overviewWater as a solventInorganic ions and their rolesMonosaccharides and the glycosidic bondDisaccharides and polysaccharidesLipids, triglycerides and phospholipidsAmino acids and protein structureProtein shape, conjugated proteins and prionsNucleic acids: nucleotides, DNA and RNADNA replication and the Meselson–Stahl experimentBiochemical tests and paper chromatography
Enzymes
Topic overviewEnzymes as globular proteins and the active siteSpecificity, cofactors and coenzymesActivation energy and models of enzyme actionThe effect of temperature and pHThe effect of substrate and enzyme concentrationCompetitive and non-competitive inhibitionEnzymes as biomarkers of disease and inhibitors as drugsImmobilised enzymes and biosensors
Viruses and Cell Structure
Topic overviewBacteriophage and HIV structureViral replication in host cellsProkaryotic and eukaryotic cells comparedMembrane structure: the fluid mosaic modelFunctions of membrane componentsMitochondria and chloroplastsRibosomes, endoplasmic reticulum, Golgi apparatus and lysosomesThe nucleus, the cytoskeleton and plasmodesmataPlant, fungal and animal cellsMicroscopy, cell measurement and cell fractionation
Cell Physiology and Transport
Continuity of Cells
Topic overviewThe cell cycle: interphase and the gap phasesControl points in the cell cycle and cancerChromosome structure, haploidy and diploidyMitosis: the events of the four stagesCytokinesis and the significance of mitosisAnticancer drugs and the cell cycleMeiosis I and the first divisionMeiosis II and the significance of meiosisPreparing and examining slides of cell division
Tissues and Organs
Exchange Surfaces and Gas Exchange
Topic overviewSurface area, volume and the surface area to volume ratioFeatures of efficient exchange surfacesThe need for mass transport systemsFick's law and the rate of gas exchangeGas exchange in plants and the compensation pointGas exchange at the alveolusThe respiratory tree and the mechanism of ventilationThe effects of smoking on the breathing systemUsing a respirometer to measure gas exchange
Transport in Plants
Topic overviewEpidermis, endodermis and the tissues of the rootXylem vessels and their lignification patternsPhloem: sieve-tube elements and companion cellsWater and mineral ion uptake by root hairsThe apoplast and symplast pathwaysTranspiration and the factors affecting its rateCohesion-tension theory and the transpiration streamTranslocation of organic solutes in the phloemXerophytes and hydrophytes
The Circulatory System in Mammals
Topic overviewDouble circulation and the major blood vesselsThe structure and function of arteries, veins and capillariesAtherosclerosis, atheroma and the investigation of blood vesselsThe structure of the mammalian heartThe cardiac cycle and the operation of the valvesMyogenic stimulation and the electrocardiogramBlood cells and the stained blood filmPlasma, tissue fluid and blood clottingHaemoglobin and the oxygen dissociation curveThe Bohr effect, myoglobin and altitude
Adaptation and Biodiversity
Topic overviewAdaptation and the ways organisms meet environmental challengesEcological factors and the ecological nicheSampling procedures and sampling devicesEstimating abundance, density, frequency and percentage coverThe biochemical basis of life and the levels of biodiversityMeasuring species diversity with Simpson's indexHandling data: averages, spread and the t-testTaxonomy, nomenclature and the binomial systemThe concept of a speciesThe taxonomic hierarchy from genus to kingdomPhylogenetic taxonomy and molecular evidenceThe five kingdom system: prokaryotae, protoctista and fungiPlantae, animalia and alternative classification systems
Human Impact on Biodiversity
Topic overviewMonoculture, polyculture and intensive agricultureCrop rotation and hedgerow conservationPredator strips, pesticides and integrated pest managementOrganic pollution of waterways by slurry and silage effluentEutrophication and fertiliser run-offBiological oxygen demand and reducing aquatic pollutionConservation initiatives and habitat protectionGlobal warming, climate change and biodiversity
Homeostasis and Excretion
Topic overviewPrinciples of homeostasis and negative feedbackExcretion, osmoregulation and nitrogenous wasteGross structure of the kidney and the urinary systemStructure of the nephron and its blood supplyEpithelia of the nephron and their adaptationsThe glomerular filterUltrafiltration and the forces that drive itSelective reabsorption in the proximal convoluted tubuleThe loop of Henlé and the medullary salt gradientADH, osmoreceptors and the control of water balance
Immunity
Topic overviewNatural barriers to infectionAntigens, antibodies and the antigen–antibody reactionAntibody-mediated immunity and B-lymphocytesCell-mediated immunity and T-lymphocytesActive immunity, passive immunity and vaccinationTransplant rejection and immunosuppressionBlood group polymorphism and the rhesus factorTransfusion compatibility and its consequencesAntibiotic resistance and the search for new antimicrobialsELISA and the detection of disease biomarkers
Co-Ordination and Control
Topic overviewPhytochromes and the control of floweringPlant growth substances and stem elongationThe structure of a neuroneResting potential, threshold and the action potentialImpulse propagation and the speed of conductionSynapse structure and chemical transmissionExcitatory and inhibitory post-synaptic potentialsGross structure of the eye and accommodationThe retina, rods and conesSkeletal muscle and the sliding filament theory
Populations and Communities
Topic overviewPopulation growth curves, carrying capacity and environmental resistancer-selected and K-selected speciesInteractions between populationsBiological control of pest speciesPopulation dynamics and changes in population sizeEstimating population size in the field and the laboratoryCommunities and ecosystemsSuccession and climax communities
Ecological Energetics and Nutrient Cycling
Topic overviewFood chains, food webs and detritus food chainsTrophic levels, gross and net primary productionEcological pyramids and their usefulnessEnergy transfer efficiency between trophic levelsWhy energy is lost at each trophic levelImplications for agriculture and intensive farmingThe carbon cycleThe nitrogen cycle and the role of bacteria
Respiration
Topic overviewATP and the ATP/ADP cycleGlycolysisThe mitochondrion and the sites of aerobic respirationThe link reaction and the Krebs cycleThe electron transport chain and oxidative phosphorylationATP yield from one molecule of glucoseAnaerobic respiration in animals, plants and fungiAerobic and anaerobic respiration compared, and oxygen debtRespiratory quotient and measuring respiration
Photosynthesis
Topic overviewChloroplast structure and the sites of photosynthesisPhotosynthetic pigments and paper chromatographyAbsorption spectra and action spectraPhotosystems, photoactivation and the Z-schemePhotolysis of water, reduced NADP and redox indicatorsCarbon dioxide fixation and rubiscoReduction of glycerate phosphate and regeneration of ribulose bisphosphateLimiting factors, the compensation point and measuring photosynthesis
DNA as the Genetic Code
Topic overviewGenes and the nature of the genetic codeExons, introns and RNA splicingComparing DNA and RNATranscription and RNA polymeraseTransfer RNA, ribosomes and the sites of translationTranslation and polypeptide synthesisOne gene, one polypeptide and the control of the phenotypeEpigenetics, methylation and histone modification
Gene Technology
Topic overviewThe polymerase chain reactionDNA probes and genetic markersMicroarrays, pharmacogenetics and personalised medicineGenetic fingerprinting and gel electrophoresisThe stages of gene transferGenetically modified microorganismsTransgenic animals and plantsGene therapyGenome sequencing and the Human Genome ProjectGene inactivation and knockout organismsSocial, ethical and ecological issues of gene technology
Genes and Patterns of Inheritance
Topic overviewGenotype, phenotype and the environmentChromosomes, genes and allelesMonohybrid inheritance and Mendel's first lawCodominance, multiple alleles and lethal allelesTest crossesDihybrid inheritance and Mendel's second lawAutosomes, sex chromosomes and sex determinationGene interaction and epistasisPolygenic inheritance and continuous variationThe chi-squared test
Population Genetics and Evolution
Evolutionary Trends in Plants
Population Genetics and Evolution
- 8 subtopics
- 24 things to know
- Unit A2 2
What Population Genetics and Evolution covers
Population Genetics and Evolution is examined in Unit A2 2, Biochemistry, Genetics and Evolutionary Trends, and drawn on again in Unit A2 3, the practical skills examination. It covers the gene pool, the Hardy–Weinberg equation, the Hardy–Weinberg principle and its conditions, sources of genetic variation, fitness and the process of selection, stabilising and directional selection, species and speciation and evidence and argument in evolutionary biology.
Where it is assessed
Unit A2 2
Biochemistry, Genetics and Evolutionary Trends, and again in Unit A2 3, Practical Skills in Biology.
Check the CCEA specification ↗The 8 subtopics
Each one has its own page.
- The gene poolGene pool, population, in the genetic sense and allele frequency.Open →
- The Hardy–Weinberg equationRecall questions on the meaning of p and q and of each term of the equation, why only the homozygous recessive frequency can be measured directly, and worked calculations of allele, genotype and carrier frequencies.Open →
- The Hardy–Weinberg principle and its conditionsHardy–Weinberg principle, genetic equilibrium and five conditions the principle requires.Open →
- Sources of genetic variationUltimate source of all new genetic variation, gene mutation and base substitution.Open →
- Fitness and the process of selectionFitness in the biological sense, selection in terms of alleles and selection pressure.Open →
- Stabilising and directional selectionStabilising selection, directional selection and how antibiotic resistance spreads through a bacterial population.Open →
- Species and speciationInfertile hybrid, allopatric speciation and three kinds of geographical barrier.Open →
- Evidence and argument in evolutionary biologyRecall questions on the fossil record and its limitations, comparative biochemistry, antibiotic resistance as evolution observed directly, the peppered moth and the criticisms of the classic studies, and why no single line of evidence carries the case alone.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
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What is genetic drift, why does population size matter to it, and what is gene flow?
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State the Hardy–Weinberg equation.
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What is genetic equilibrium?
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What is the ultimate source of all new genetic variation?
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What does selection act on?
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What is stabilising selection?
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Define a species.
Evaluation
Give one limitation of the fossil record as evidence.
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What do p and q represent in the Hardy–Weinberg equation?
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List the five conditions the Hardy–Weinberg principle requires
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What is a gene mutation?
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Why can selection not act where there is no variation?
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When does stabilising selection predominate?
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Why does the definition of a species include the word fertile?
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How does comparative biochemistry support common ancestry?
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What is a gene pool?
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What does each term of the Hardy–Weinberg equation represent?
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Why must the population be large for the Hardy–Weinberg principle to hold?
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Name the two kinds of gene mutation studied as sources of variation
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Define selection in terms of alleles.
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Give an example of stabilising selection in humans.
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Give an example of an infertile hybrid.
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How does antibiotic resistance provide evidence of evolution within a human lifetime?
Take Population Genetics and Evolution further
The same content, four other ways.
Questions from this topic
Each one with the model answer underneath.
- 1
What is a gene pool?
Model answer
The total sum of all the alleles of all the genes present in a population at a given time.
- 2
What is a population, in the genetic sense?
Model answer
A group of individuals of the same species living in the same place and able to interbreed.
- 3
What is meant by an allele frequency?
Model answer
The proportion of all the alleles at a locus in a population that are of a particular kind.
- 4
What is meant by a genotype frequency?
Model answer
The proportion of the individuals in a population that carry a particular combination of alleles.
- 5
How does a gene pool differ from a genotype?
Model answer
A genotype belongs to one individual, while the gene pool is the whole population's collection of alleles considered together.
- 6
Why is evolution described as a change in a gene pool rather than in an individual?
Model answer
An individual's alleles are fixed at fertilisation, so only the proportions across a population can change over generations.
What is inside Levo
Six ways to work the same material.
Population Genetics and Evolution revision questions
- What does Population Genetics and Evolution cover in CCEA A-Level Biology?
- 8 subtopics: the gene pool, the hardy–weinberg equation, the hardy–weinberg principle and its conditions, sources of genetic variation, fitness and the process of selection, stabilising and directional selection, species and speciation and evidence and argument in evolutionary biology. Each one has its own page with questions and model answers.
- How is Population Genetics and Evolution organised?
- By the CCEA 1010 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Population Genetics and Evolution, 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.
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