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
Populations and Communities
- 8 subtopics
- 24 things to know
- Unit A2 1
What Populations and Communities covers
Populations and Communities is examined in Unit A2 1, Physiology, Co-ordination and Control, and Ecosystems, and drawn on again in Unit A2 3, the practical skills examination. It covers population growth curves, carrying capacity and environmental resistance, r-selected and K-selected species, interactions between populations, biological control of pest species, population dynamics and changes in population size, Estimating population size in the field and the laboratory, Communities and ecosystems and succession and climax communities.
Where it is assessed
Unit A2 1
Physiology, Co-ordination and Control, and Ecosystems, and again in Unit A2 3, Practical Skills in Biology.
Check the CCEA specification ↗The 8 subtopics
Each one has its own page.
- Population growth curves, carrying capacity and environmental resistanceFour phases of a population growth curve in order, what happens during the lag phase and exponential phase of population growth.Open →
- r-selected and K-selected speciesR-selected species and K-selected species.Open →
- Interactions between populationsIntraspecific and interspecific competition and predation and parasitism.Open →
- Biological control of pest speciesPest species, biological control and integrated pest management.Open →
- Population dynamics and changes in population sizeFour processes that determine the size of a population, how these four processes combine to change a population and density-dependent and density-independent factors.Open →
- Estimating population size in the field and the laboratoryCapture–mark–recapture technique, relationship used to estimate population size from a capture–mark–recapture study and three assumptions made when using capture–mark–recapture.Open →
- Communities and ecosystemsThree abiotic factors of a woodland ecosystem, habitat and a niche and saying that the species of a community are interdependent.Open →
- Succession and climax communitiesPioneer species, climax community and primary succession.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
Why is competition harmful to both species, what two forms does it take, and what is mutualism?
Key term
What is a population?
Key term
What is a pest species?
Process
Name the four processes that determine the size of a population.
Numbers
The central grid of a haemocytometer measures 1 mm by 1 mm and the liquid above it is 0.1 mm deep. Calculate the volume counted.
Key term
What is a community?
Key term
What is succession?
Key term
Name the four phases of a population growth curve in order.
Key term
What is a K-selected species?
Key term
How is competition classified in terms of its effect on the two species involved?
Key term
What is biological control?
Key term
What is immigration?
Numbers
A total of 250 yeast cells is counted over a grid holding 0.1 mm³ of suspension. Calculate the cell density in cells per mm³.
Key term
Why is a community described as the biotic component of an ecosystem?
Key term
What is a pioneer species?
Key term
Describe what happens during the lag phase.
Key term
What does the letter r in r-selected stand for?
Key term
Distinguish between intraspecific and interspecific competition.
Key term
Name two kinds of organism used as biological control agents.
Key term
What is emigration?
Key term
Express a yeast density of 2500 cells mm⁻³ in cells per cm³.
Key term
What is an ecosystem?
Key term
Give two features that make a species a good pioneer.
Take Populations and Communities further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Habitat vs Niche
Habitat: the physical place where an organism lives. Niche: the role it plays there, including what it eats and what interacts with it.
Questions from this topic
Each one with the model answer underneath.
- 1
What is a population?
Model answer
A population is all the individuals of one species living in the same place at the same time and able to interbreed.
- 2
Name the four phases of a population growth curve in order.
Model answer
The four phases are the lag phase, the exponential or log phase, the stationary phase and the decline phase.
- 3
Describe what happens during the lag phase.
Model answer
Numbers rise very slowly at first while the few individuals present become established and adjust to the conditions.
- 4
Describe the exponential phase of population growth.
Model answer
Numbers double in each successive interval of time, so the population rises steeply because resources are plentiful and competition is slight.
- 5
Describe the shape of a growth curve for a population that levels off at the carrying capacity.
Model answer
The curve is S-shaped, rising slowly at first, then steeply, and finally flattening into a plateau.
- 6
What is meant by the carrying capacity of a habitat?
Model answer
The carrying capacity is the maximum population size of a species that a particular habitat can support indefinitely.
What is inside Levo
Six ways to work the same material.
Populations and Communities revision questions
- What does Populations and Communities cover in CCEA A-Level Biology?
- 8 subtopics: population growth curves, carrying capacity and environmental resistance, r-selected and k-selected species, interactions between populations, biological control of pest species, population dynamics and changes in population size, estimating population size in the field and the laboratory, communities and ecosystems and succession and climax communities. Each one has its own page with questions and model answers.
- How is Populations and Communities organised?
- By the CCEA 1010 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Populations and Communities, 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.