Key term
Edexcel GCSE Biology 1BI0
Key Concepts in Biology
Topic overviewEukaryotic and prokaryotic cellsSpecialised cells and their adaptationsMicroscopes and magnification calculationsSize, scale and units in cell biologyEnzyme action and denaturationFactors affecting enzyme activityEnzymes in synthesis and digestion, and rate calculationsFood tests and the energy in foodDiffusion, osmosis and active transportOsmosis in potatoes and percentage change in mass
Cells and Control
Topic overviewMitosis and the cell cycleWhy mitosis matters: growth, repair and cancerGrowth, differentiation and percentile chartsStem cells and their use in medicineThe structure and function of the brainInvestigating and treating the brainNeurones, receptors and the reflex arcThe structure and function of the eyeEye defects and how they are corrected
Genetics
Topic overviewAsexual and sexual reproductionMeiosis and the formation of gametesDNA structure, genes and the genomeExtracting DNA from fruitProtein synthesis: transcription and translationGenetic variants in coding and non-coding DNAMendel's work and the inheritance of blood groupsAlleles, genotype and phenotypeMonohybrid crosses and sex determinationProbability and ratios from genetic crossesSex-linked disordersCauses of variation: genes and environmentThe Human Genome ProjectGenetic variation and the effects of mutation
Natural Selection and Genetic Modification
Topic overviewDarwin, Wallace and the theory of evolutionNatural selection and antibiotic resistanceFossil evidence for human evolutionStone tool evidence for human evolutionThe pentadactyl limb and the three domainsSelective breedingTissue cultureGenetic engineering and modern agricultureThe stages of genetic engineeringBenefits and risks of GM organisms
Health, Disease and the Development of Medicines
Topic overviewHealth, disease and susceptibilityPathogens and common infectionsHow pathogens spread, and the virus life cycleSexually transmitted infectionsHow plants defend themselves and how plant disease is detectedPhysical barriers and chemical defencesThe immune system, immunisation and herd immunityAntibiotics and developing new medicinesAseptic technique in culturing microorganismsTesting antiseptics and antibiotics on bacterial culturesMonoclonal antibodiesLifestyle factors and non-communicable diseaseTreatments for cardiovascular disease
Plant Structures and Their Functions
Topic overviewPhotosynthesis as an endothermic reactionLimiting factors in photosynthesisLight intensity and the rate of photosynthesisRoot hair cells, xylem and phloemTranspiration and translocationLeaf structure for photosynthesis and gas exchangeFactors affecting the rate of transpirationPlant adaptations to extreme environmentsPlant hormones and their commercial uses
Animal Coordination, Control and Homeostasis
Topic overviewHormones, endocrine glands and homeostasisAdrenalin, thyroxine and negative feedbackThe menstrual cycle and its hormonesHormonal and barrier contraceptionAssisted reproductive technology and IVFHomeostasis and thermoregulationControlling blood glucose, and type 1 diabetesType 2 diabetes and body massThe urinary system and the production of ureaThe nephron, filtration and the effect of ADHTreating kidney failure: dialysis and transplants
Exchange and Transport in Animals
Topic overviewWhy multicellular organisms need exchange surfacesAlveoli and gas exchangeRate of diffusion and Fick's lawThe blood and its componentsArteries, veins and capillariesThe heart and the circulatory systemCellular respiration as an exothermic reactionAerobic and anaerobic respiration comparedInvestigating the rate of respirationCardiac output, stroke volume and heart rate
Ecosystems and Material Cycles
Topic overviewLevels of organisation and interdependenceAbiotic and biotic factors in a communityParasitism and mutualismSampling with quadrats and transectsEstimating population size from field dataEnergy transfer between trophic levelsHuman impact on ecosystems and biodiversityFood securityThe carbon cycleThe water and nitrogen cyclesIndicator species and pollutionFactors affecting the rate of decompositionCalculating the rate of decay
Ecosystems and Material Cycles
Estimating population size from field data
- 3 things to know
- Paper 2
Overview
Scaling a quadrat mean up to a whole site, working the mean per square metre from quadrats of different sizes, why the result is only an estimate, and transect counts.
What you need to know
Answer each one before you reveal it.
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Key term
Ten quadrats of 1 m² placed in a 500 m² field contain 45 dandelions in total. Estimate the number of dandelions in the field.
Numbers
Twenty quadrats, each of area 0.25 m², contain 60 buttercup plants altogether. Calculate the mean number of buttercups per square metre.
Questions from this subtopic
Each one with the model answer underneath.
- 1
State the rule used to estimate the total number of plants in an area from quadrat data.
Model answer
Multiply the mean number of plants per square metre by the total area of the site in square metres.
- 2
Ten quadrats of 1 m² placed in a 500 m² field contain 45 dandelions in total. Estimate the number of dandelions in the field.
Model answer
The mean is 4.5 per m², so the estimate is 4.5 × 500 = 2250 dandelions.
- 3
Twenty quadrats, each of area 0.25 m², contain 60 buttercup plants altogether. Calculate the mean number of buttercups per square metre.
Model answer
The quadrats cover 20 × 0.25 = 5 m², so the mean is 60 ÷ 5 = 12 buttercups per m².
- 4
A meadow measures 40 m by 25 m and quadrat sampling gives a mean of 3 clover plants per square metre. Estimate the clover population of the meadow.
Model answer
The meadow covers 1000 m², so the estimate is 3 × 1000 = 3000 clover plants.
- 5
Five quadrats, each 0.5 m by 0.5 m, on a 200 m² lawn contain 2, 4, 3, 5 and 6 plantains. Estimate the number of plantains on the lawn.
Model answer
The mean is 4 per quadrat, which is 16 per m², so the estimate is 16 × 200 = 3200 plantains.
- 6
Explain why a population size worked out from quadrat data is only an estimate.
Model answer
Only a small fraction of the area is actually counted, and that sample may not exactly match the whole site.
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