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 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 fruitMendel's work and the inheritance of blood groupsAlleles, genotype and phenotypeMonohybrid crosses and sex determinationProbability and ratios from genetic crossesCauses 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 agricultureBenefits 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 themselvesPhysical barriers and chemical defencesThe immune system, immunisation and herd immunityAntibiotics and developing new medicinesAseptic technique in culturing microorganismsTesting antiseptics and antibiotics on bacterial culturesLifestyle 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, phototropism and gravitropism
Animal Coordination, Control and Homeostasis
Topic overviewHormones, endocrine glands and homeostasisThe menstrual cycle and its hormonesHormonal and barrier contraceptionHomeostasis and thermoregulationControlling blood glucose, and type 1 diabetesType 2 diabetes and body massThe urinary system and the production of ureaThe nephron, filtration and selective reabsorptionTreating 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 cyclesFactors affecting the rate of decompositionCalculating the rate of decay
Ecosystems and Material Cycles
Calculating the rate of decay
- 3 things to know
- Paper 2
Overview
Mean rate of decay from mass lost over time, comparing rates at two temperatures, mass remaining after a period or after a percentage loss, and why decay slows later.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Numbers
A 40 g sample of grass cuttings decays at a mean rate of 1.6 g per day. Calculate the mass remaining after 5 days.
Numbers
A 120 g sample of grass cuttings has lost 45% of its mass after three weeks. Calculate the mass remaining.
Questions from this subtopic
Each one with the model answer underneath.
- 1
How is the mean rate of decay of a sample calculated from its change in mass?
Model answer
Divide the mass lost by the time taken for that loss.
- 2
A sample of leaf litter falls from 80 g to 50 g in 10 days. Calculate the mean rate of decay.
Model answer
It loses 30 g in 10 days, so the rate is 30 ÷ 10 = 3 g per day.
- 3
A 200 g sample of food waste loses 60 g of its mass in 15 days. Calculate the mean rate of decay in grams per day.
Model answer
60 ÷ 15 = 4 g per day.
- 4
Compost decays at 2 g per day at 15 °C and at 5 g per day at 25 °C. Calculate how many times faster the decay is at the higher temperature.
Model answer
5 ÷ 2 = 2.5 times faster.
- 5
A 40 g sample of grass cuttings decays at a mean rate of 1.6 g per day. Calculate the mass remaining after 5 days.
Model answer
1.6 × 5 = 8 g is lost, so 40 − 8 = 32 g remains.
- 6
A 120 g sample of grass cuttings has lost 45% of its mass after three weeks. Calculate the mass remaining.
Model answer
45% of 120 g is 54 g lost, so 120 − 54 = 66 g remains.
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