Edexcel GCSE Biology
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Common to Papers 1 and 2
Topic 1 - Key concepts in biology
1.1 - Cell structures and functionsCompare animal, plant and bacterial cells, and explain how each required sub-cellular structure helps the cell function. Use structure and function together to interpret unfamiliar cells.
1.2 - Specialised cellsExplain how sperm and egg cells are adapted for fertilisation and how ciliated epithelial cells clear the airways. Connect each feature to the biological job it makes possible.
1.3 - 1.5 - Microscopy, scale and unitsExplain how microscope technology reveals finer cell detail, estimate cell sizes and convert between milli-, micro-, nano- and picometres. A clearly marked Higher-tier part develops calculations in standard form.
1.6 - Microscopy practicalPrepare plant and animal specimens, bring them into focus and make labelled scientific drawings from observations. Use lens values, image sizes and scale bars to calculate magnification and actual size; all of this lesson applies to both tiers.
1.7 - 1.9 - Enzyme action and conditionsExplain how an enzyme’s active site makes its action specific, then use that mechanism to interpret changes in activity with temperature, pH and substrate concentration.
1.10 - 1.11 - Investigating enzyme activityInvestigate how pH affects the breakdown of starch by amylase. Plan valid measurements, understand the iodine endpoint and calculate enzyme activity from reaction times or product measurements.
1.12 - Building and breaking moleculesFollow enzyme-catalysed reactions that build carbohydrates, proteins and lipids or break them into smaller molecules. Explain why these reactions are essential for digestion, growth and repair.
1.13B - Food testsUse chemical reagents to identify starch, reducing sugars, proteins and lipids. Connect each method to its observation and use controls, separate samples and appropriate precautions to make conclusions trustworthy.
1.14B - Food calorimetryMeasure energy transferred from burning food to water, calculate an estimate per gram of food burned and explain why simple calorimetry usually underestimates food energy.
1.15 - Cell transportCompare diffusion, osmosis and active transport by what moves, the direction of net movement and the need for energy. Apply these mechanisms to cells and to changes in potato tissue.
1.16 - 1.17 - Osmosis practicalInvestigate how sucrose concentration changes potato mass. Use a controlled method, calculate percentage gains and losses and interpret the concentration at which there is no net water movement.
Paper 1
Topic 2 - Cells and control
2.1 - 2.4 - Mitosis and cell divisionFollow the cell cycle from chromosome copying to two genetically identical daughter cells. Explain why controlled mitosis supports growth, repair and asexual reproduction, and how loss of that control can lead to cancer.
2.5 - 2.7 - Growth and differentiationExplain how division, elongation and differentiation build growing organisms. Then use percentile charts to distinguish absolute growth from a child’s changing position in a reference group.
2.8 - 2.9 - Stem cellsCompare the functions of embryonic stem cells, animal tissue stem cells and plant meristems. Follow how cell replacement could restore tissue function and weigh evidence for medical benefits, risks and ethical concerns.
2.10B - Brain structure and functionLocate the cerebral hemispheres, cerebellum and medulla oblongata, and relate each to its functions. Explain how different regions can contribute to the same activity. This Biology-only lesson applies to both tiers.
2.11B - 2.12B - Brain imaging and treatmentUse CT and PET evidence to investigate brain function without opening the skull. Explain why spinal injuries and brain tumours can remain difficult to treat. This Biology-only lesson is Higher tier.
2.13 - 2.14 - Nerves, synapses and reflex arcsTrace how receptors detect a stimulus, neurones carry electrical impulses and synapses transfer the signal chemically. Use these structures to explain how a reflex moves a muscle rapidly without waiting for a conscious decision.
2.15B - How the eye worksFollow light through the eye, explain how rods and cones produce sensory information, and distinguish the iris response to light from lens accommodation. This Biology-only lesson applies to both tiers.
2.16B - 2.17B - Vision defects and correctionDistinguish focusing errors, cataracts and colour vision deficiency by where the fault occurs. Explain how lenses, corneal reshaping and lens replacement correct the appropriate defects. This Biology-only lesson applies to both tiers.
Topic 3 - Genetics
3.1B - 3.3 - Reproduction and meiosisCompare how sexual and asexual reproduction balance speed with genetic variation. Learn how meiosis produces genetically different haploid cells and why halving the chromosome number matters for sexual reproduction.
3.4 - 3.5 - DNA, genes and genomesBuild a DNA molecule from nucleotides and complementary base pairs, then distinguish a protein-coding gene from an organism’s whole genome.
3.6 - Extracting DNA from fruitFollow a fruit DNA extraction from broken tissue to a visible precipitate. Explain what each step does, what to keep after filtering, and why the collected material is a crude DNA-containing extract.
3.7B - 3.8B - Protein synthesisHigher tier: follow genetic information from DNA through transcription and translation to a folded protein. Connect the jobs of RNA polymerase, mRNA, ribosomes and tRNA to the order of amino acids.
3.9B - 3.10B - Genetic variants and proteinsHigher tier: compare two routes from a DNA variant to a changed characteristic. Use your knowledge of transcription and translation to distinguish changes in protein quantity from changes in protein shape and activity.
3.11B - 3.13 - Mendel and inheritance termsUse Mendel’s pea-plant evidence to explain how inherited information can remain hidden and reappear. Connect chromosomes, genes and alleles to genotypes, phenotypes, gametes and zygotes.
3.14 - 3.16 - Genetic crosses and pedigreesFollow alleles through monohybrid crosses and family pedigrees. Calculate probabilities, ratios and percentages, and apply the same gamete-to-zygote reasoning to the standard XX/XY model of sex determination.
3.17B - ABO blood-group inheritanceExtend simple genetic crosses to a gene with three alleles in the population. Use ABO blood groups to distinguish codominance from dominance and work out which blood groups offspring could inherit.
3.18B - Sex-linked inheritanceHigher tier: trace an X-linked recessive allele through parents, gametes and offspring. Explain why the pattern differs between sons and daughters and distinguish a probability among sons from a probability among all children.
3.19 - 3.20 - VariationExplain how genes and environment contribute to differences between individuals. Distinguish a new DNA variant from a new combination of inherited alleles and use evidence to identify acquired differences.
3.21 - The Human Genome ProjectDiscover what the Human Genome Project produced and how reference-genome data support medicine. Weigh a specific medical benefit against scientific uncertainty, privacy and consent.
3.22 - 3.23 - MutationExplain how mutations supply the genetic variants found within populations. Interpret evidence showing that most mutations have no observable effect, some have a small effect and only rarely does one have a large effect.
Topic 4 - Natural selection and genetic modification
4.1B - 4.3 - Natural selection and resistanceFollow how inherited variation, survival and reproduction change populations over generations. Use Darwin and Wallace’s work and the spread of antibiotic resistance to explain natural selection.
4.4 - 4.5 - Evidence for human evolutionUse the dated fossils of Ardi, Lucy and Richard Leakey’s team, together with stone tools, to reconstruct evidence for human evolution. Distinguish what is observed from what can reasonably be inferred.
4.6B - 4.7 - Evolutionary relationships and classificationUse shared limb anatomy and DNA comparisons to infer evolutionary relationships. Explain why genetic evidence led scientists to separate Bacteria and Archaea in the three-domain classification.
4.8 - Selective breedingExplain how choosing parents changes inherited characteristics over generations. Apply selective breeding to food plants and domesticated animals, balancing production gains against genetic diversity and welfare.
4.9B - Tissue cultureFollow how cells and tissues are grown outside an organism under controlled conditions. Explain how plant tissue culture multiplies a selected genotype and why cell cultures are useful, but limited, models in medical research.
4.10 - Genetic engineeringExplain what it means to modify an organism’s genome deliberately. Trace the difference between inserting a gene, producing its protein and obtaining the intended useful characteristic.
4.11 - Genetic engineering methodsHigher tier: follow a selected gene from donor DNA into a recipient cell. Distinguish the jobs of restriction enzymes, complementary sticky ends, DNA ligase and a plasmid vector.
4.12B - GM cropsExplain how a crop carrying a gene from Bacillus thuringiensis can resist a target insect pest. Evaluate benefits and risks by tracing the consequences for crop damage, resistance, gene flow and farming costs.
4.13B - Agriculture and food demandExplore how fertilisers and biological control can help agriculture meet rising food demand. Connect each method to useful crop yield and weigh its benefits against environmental and practical limitations.
4.14 - Biotechnology choicesCompare selective breeding and genetic engineering as choices in agriculture and medicine. Build a reasoned judgement from biological benefits and risks, practical constraints and ethical implications.
Topic 5 - Health, disease and the development of medicines
5.1 - 5.4 - Health, disease and pathogensHealth includes physical, mental and social well-being. Learn how diseases differ, what makes an organism a pathogen, and why one disease can make another more likely.
5.5 - 5.6 - Infection spreadConnect each named infection to its pathogen, its effects and its transmission route. Use those links to explain why a particular prevention measure interrupts spread, and why HIV damage can make other infections more likely.
5.7B - Viral lifecyclesFollow how a bacteriophage reproduces inside a bacterial host. Compare immediate virus production and lysis with copying integrated viral DNA through host-cell divisions, and explain a later switch between the pathways.
5.8 - Sexually transmitted infectionsExplain how Chlamydia and HIV can pass during sexual contact. Distinguish infection from symptoms, compare barrier prevention with testing and treatment, and explain why preventing pregnancy does not necessarily prevent infection.
5.9B - 5.10B - Plant defencesLearn how a plant’s waxy cuticle, cell walls and defensive chemicals reduce attack by pests and pathogens. Connect a plant chemical’s biological activity with its possible use in a carefully controlled human medicine.
5.11B - Identifying plant diseaseHigher tier, separate Biology. Use symptoms, the distribution of affected plants and environmental checks to investigate a suspected plant disease. Explain how suitable laboratory tests can identify a pathogen more specifically than field clues alone.
5.12 - Human barriers and defencesExplain how skin, mucus and cilia reduce pathogen entry, then follow how lysozyme and stomach acid act on microorganisms. Connect each defence’s structure or action to the protection it provides.
5.13 - 5.15B - Immune response and vaccinationLearn how antibodies recognise a pathogen and how memory lymphocytes improve a later response. Use these mechanisms to explain vaccination, herd immunity and the benefits and limitations of immunisation.
5.16 - 5.19B - Antibiotics and antimicrobial practicalExplain why antibiotics can act selectively on bacteria, then design a fair antimicrobial comparison using aseptic cultures. Interpret clear zones cautiously and calculate circular bacterial-colony or clear-zone areas.
5.20 - Developing medicinesFollow a promising substance through discovery, development, preclinical tests and clinical trials. Explain why evidence of a useful effect must be considered alongside safety, dose and the quality of the comparison.
5.21B - Producing monoclonal antibodiesHigher tier, separate Biology. Learn why a continuing supply of one specific antibody requires cell fusion, selection and cloning. Explain how a hybridoma combines antibody production with repeated cell division.
5.22B - Using monoclonal antibodiesHigher tier, separate Biology. Apply specific antibody binding to pregnancy tests, scans that locate clots or cancer cells, and targeted cancer treatment. Explain both the useful selectivity and its limitations.
5.23 - 5.24 - Lifestyle and disease riskExplain how lifestyle, inherited and environmental factors interact in non-communicable disease. Calculate BMI and waist:hip ratio, trace diet, exercise, alcohol and smoking effects, and consider disease patterns at local, national and global scales.
5.25 - Cardiovascular treatmentsCompare how medicines, stents, bypass surgery and lifestyle changes address cardiovascular disease. Use a patient’s stated circumstances to weigh present blood-flow benefits, future risk, side effects and practical limitations.
Paper 2
Topic 6 - Plant structures and their functions
6.1 - 6.2 - PhotosynthesisPlants and algae use light energy to make glucose from carbon dioxide and water. Explain the photosynthesis reaction and trace how its products supply food and new biomass.
6.3 - 6.4 - Limiting factorsExplain how light intensity, carbon dioxide and temperature limit photosynthesis, and interpret patterns in rate data. Higher learners also use changes in several conditions to identify shifting limiting factors.
6.5 - Photosynthesis practicalUse algal balls to investigate the effect of light intensity on photosynthesis. Plan a fair comparison, turn indicator readings into a rate and judge the quality of the evidence.
6.6 - Inverse square lawUse the inverse square law to connect lamp distance with light intensity and predict photosynthesis rates. This Higher lesson develops the calculations and the conditions under which the model works.
6.7 - 6.10 - Plant transport systemsFollow water and mineral ions from the soil to the leaves, then trace sucrose from a source to a sink. Connect root hairs, xylem, phloem and stomata to their roles in transport.
6.11B - Leaf structureExplore how the tissues of a leaf bring light, carbon dioxide and water to photosynthesising cells. Link each structural feature to photosynthesis or gas exchange.
6.12 - 6.13 - Water uptake and ratesExplain how light, temperature and air movement change transpiration and water uptake. Calculate rates from changes in water mass or volume, with the units and time interval matched correctly.
6.14B - Plants in extreme environmentsExplain how leaf size, shape, cuticle and stomata help plants conserve water in extreme environments. Use these mechanisms to judge adaptation evidence and the trade-off with photosynthesis.
6.15B - Auxin and tropismsExplain how auxin coordinates directional growth in shoots and roots. Follow changes in auxin distribution and cell elongation to account for phototropism and gravitropism.
6.16B - Commercial uses of plant hormonesExplore how growers use auxins, gibberellins and ethene to control plant development. This Higher Biology lesson connects each treatment with its intended commercial outcome.
Topic 7 - Animal coordination, control and homeostasis
7.1 - The endocrine systemLocate the main endocrine glands and distinguish a hormone’s source, blood transport and target organ. Explain why a circulating hormone causes a response only in particular cells.
7.2 - Adrenalin and fight or flightExplain how adrenalin coordinates the body’s response to a sudden threat. This Higher lesson links changes in circulation and blood glucose to the needs of active muscles.
7.3 - Thyroxine and feedbackTrace the hormonal pathway that controls thyroxine and metabolic rate. This Higher lesson explains how negative feedback increases a low thyroxine level and then reduces further stimulation.
7.4 - 7.5 - The menstrual cycleFollow changes in the ovaries and uterus through a menstrual cycle. Learn the common-tier roles of oestrogen and progesterone, then explore the four-hormone control sequence at Higher tier.
7.6 - 7.7 - ContraceptionExplain how hormonal and barrier contraception reduce the chance of pregnancy. Compare methods using evidence about effectiveness, user action, side effects and protection from sexually transmitted infections.
7.8 - Fertility treatmentCompare clomifene therapy with IVF and explain the role of hormones at each stage. This Higher lesson distinguishes egg maturation, fertilisation, embryo transfer and implantation.
7.9 - 7.10B - Why homeostasis mattersExplain why the body maintains a stable internal environment despite internal and external changes. Connect temperature control to enzyme activity and water balance to animal-cell volume.
7.11B - 7.12B - ThermoregulationTrace temperature changes through receptors, the hypothalamus and effectors. Explain how sweating and shivering help restore temperature; vasodilation and vasoconstriction are Higher-only mechanisms.
7.13 - 7.14 - Blood glucose controlExplain how insulin lowers raised blood glucose by changing glucose uptake and storage. Higher learners also explain how glucagon raises low blood glucose and compare the two feedback responses.
7.15 - 7.16 - DiabetesCompare the causes of type 1 and type 2 diabetes and explain how their control addresses the underlying problem. Distinguish missing insulin from a reduced response to insulin.
7.17 - Body mass and diabetes riskCalculate BMI and waist-to-hip ratio, then interpret evidence linking body mass with type 2 diabetes. Explain why useful population associations do not diagnose an individual or establish a single cause.
7.18B - 7.19B - Kidneys and urine formationKeep the blood route through the kidneys separate from the urine route to the bladder. Connect nephron structure to filtration and to the reabsorption of useful substances and water.
7.20B - ADH and water balanceExplain how ADH changes collecting-duct permeability to regulate blood water content. This Higher Biology lesson connects hormone release, water reabsorption and the volume and concentration of urine.
7.21B - 7.22B - Urea and kidney failureLocate urea production in the liver and explain why the kidneys must remove it from the blood. Compare dialysis with a donated-kidney transplant as treatments for kidney failure.
Topic 8 - Exchange and transport in animals
8.1 - 8.2 - Exchange and transport needsLearn why organisms move substances into and out of cells, and use surface area : volume ratios to explain why large organisms need specialised exchange surfaces and transport systems.
8.3 - 8.5B - Alveoli and diffusionExplain how alveoli exchange gases rapidly, then use the same surface-area, concentration and distance ideas to calculate relative diffusion rates with Fick’s law.
8.6 - Blood and its componentsConnect the structures of red and white blood cells, plasma and platelets to oxygen transport, defence, clotting and the movement of dissolved substances.
8.7 - Blood vesselsCompare arteries, veins and capillaries, explaining how their walls, lumina and valves suit the pressure, direction and exchange demands of blood flow.
8.8 - The heart and circulationFollow blood through the heart, lungs and body, and explain how chamber walls, valves, the septum and major vessels make double circulation work.
8.9 - 8.10 - Cellular respirationExplain why living cells respire continuously, compare aerobic and anaerobic pathways, and connect their products and energy release to the needs of organisms.
8.11 - Measuring respirationInvestigate aerobic respiration with a respirometer: explain the movement of its liquid marker, plan a temperature comparison, calculate rates and evaluate the control evidence.
8.12 - Cardiac output calculationsUse heart rate and stroke volume to calculate cardiac output, rearrange the equation to find either factor, and compare results in consistent units.
Topic 9 - Ecosystems and material cycles
9.1 - 9.4 - Ecosystem organisation and interdependenceExplore how organisms form populations, communities and ecosystems, and how changes in living and non-living factors affect their survival and reproduction.
9.5 - 9.6 - Fieldwork with quadrats and transectsLearn to sample organisms with random quadrats and belt transects, calculate population estimates, and judge what field evidence can show about an environmental gradient.
9.7B - 9.8B - Biomass and energy transferFollow energy and biomass through food chains, construct and interpret scaled pyramids of biomass, and calculate transfer efficiencies and biomass percentages.
9.9 - 9.10 - Human impacts and biodiversityTrace the benefits and harms of fish farming, introduced species and nutrient pollution, and explain how conservation and reforestation can maintain biodiversity.
9.11B - Food securityExplain how population growth, farming, pests, environmental change and competing resource demands affect the availability, affordability and stability of food supplies.
9.12 - 9.13 - Material cycling and carbonRead material cycles as transfers between living and non-living stores, then follow carbon through photosynthesis, feeding, respiration, decomposition and combustion.
9.14 - Water cycle and water supplyFollow water through the atmosphere, land and organisms, then explain why drought reduces freshwater supplies and how desalination can provide drinking water.
9.15 - Nitrogen cycle and farmingTrace the bacterial processes that make nitrate available to plants, and explain how fertilisers, crop rotation and waterlogging change the nitrogen supply.
9.16B - Pollution indicatorsUse water and air indicator species to evaluate pollution evidence, and judge how repeated sampling and direct measurements can strengthen a conclusion. This lesson is Higher-only separate Biology.
9.17B - 9.19B - Decomposition and decay ratesExplain how temperature, water and oxygen control decomposition, apply these ideas to food preservation and composting, and calculate changes in decay rate.