AQA GCSE Biology
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Topic 4.1: Cell biology
Subtopic 4.1.1: Cell structure
4.1.1.1 - Eukaryotes, Prokaryotes and Cell ScaleCells are the smallest living units, but they are not all organised in the same way. In this lesson, the main difference is where the genetic material is found: inside a nucleus in eukaryotic cells, but not inside a nucleus in prokaryotic bacterial cells. You will also practise the scale language...
4.1.1.2a - Animal and Plant Cell StructuresCells are easier to understand when you treat each labelled part as a structure with a job. In this lesson, the key skill is not just naming the parts of animal and plant cells, but explaining how each sub-cellular structure is related to its function. Bacterial plasmids are included only where t...
4.1.1.2b - Microscopy of Plant and Animal CellsIn this required practical, you use a light microscope to observe plant and animal cells, then record what you see as a clear labelled scientific drawing. AQA can assess the method, the apparatus, safe focusing, drawing conventions, magnification scale, and estimates of relative size or area. The...
4.1.1.3 - Cell SpecialisationDifferent cells can have different shapes and subcellular structures because they do different jobs. In this lesson, the key skill is to explain a structure-function link: name a feature, state what it does, then connect it to the cell's role in a tissue, organ, organ system or whole organism.
4.1.1.4 - Cell DifferentiationOne cell is not enough to build a complex organism. As an organism develops, cells change so that different cells can do different jobs. This change is called cell differentiation, and it is how ordinary developing cells become specialised cells.
4.1.1.5 - Microscopy, Magnification and ResolutionMicroscopes let biologists study cells and the structures inside them. As microscope technology improved, biologists could make images bigger and, more importantly, see finer detail. This lesson focuses on how light and electron microscopes differ, and how to handle magnification calculations wit...
4.1.1.6a - Culturing Microorganisms and Bacterial GrowthMicroorganisms are tiny living organisms. In this biology-only section, the focus is bacteria: how they multiply, how they can be grown in nutrient media, and how to do the calculations that come from bacterial growth on agar plates. The key pattern is doubling, so a small starting population can...
4.1.1.6b - Aseptic Technique and Zones of InhibitionIn this Biology-only required practical, you prepare an uncontaminated bacterial culture and test how well antiseptics or antibiotics inhibit bacterial growth. The result is judged from clear areas on an agar plate called zones of inhibition. The practical is really about two linked skills: keepi...
Subtopic 4.1.2: Cell division
4.1.2.1 - Chromosomes, DNA and GenesChromosomes are one of the key links between cell biology and inheritance, but this lesson keeps to the first GCSE idea: where chromosomes are, what they are made of, what they carry, and how they are normally arranged in body cells. The important exam skill is to describe the relationship betwee...
4.1.2.2 - Mitosis and the Cell CycleMulticellular organisms become larger because their cells divide as well as grow. In this topic, the important idea is that the cell cycle copies the genetic material and then divides it so two identical cells are made. You need the overall order of events, not the named phases inside mitosis.
4.1.2.3 - Stem CellsStem cells matter because they are not yet specialised. They can make more cells of the same type, and some of their cells can become specialised by differentiation. This lesson keeps the exam boundary clear: you need the functions, uses and evaluation points, not the detailed laboratory techniques.
Subtopic 4.1.3: Transport in cells
4.1.3.1a - Diffusion and Factors Affecting Its RateCells constantly exchange substances with their surroundings. Diffusion is one way particles move into and out of cells across cell membranes, and it matters because cells need useful substances while removing waste. This lesson focuses on what diffusion means, examples named in the specification...
4.1.3.1b - Surface Area to Volume Ratio and Exchange SurfacesEvery cell needs substances to move in and out across a surface. As organisms get larger, their volume increases faster than their outside surface area, so diffusion across the body surface alone becomes too slow. This lesson shows how to calculate surface area to volume ratio, then uses that ide...
4.1.3.2a - Osmosis and Water MovementWater can move into and out of cells through the cell membrane. The AQA word for this movement is osmosis, and the definition is exact: it is about water, a partially permeable membrane, and movement from a dilute solution to a concentrated solution. In this lesson you will learn how to follow th...
4.1.3.2b - Required Practical - Osmosis in Plant TissueIn this required practical, you investigate how the concentration of a salt or sugar solution affects the mass of plant tissue. The biology is osmosis, but the exam marks often come from practical detail: variables, accurate mass measurements, percentage change, graph interpretation and evaluatio...
4.1.3.3 - Active TransportCells sometimes need useful substances even when those substances are already more concentrated inside the cell or in the blood. Diffusion cannot do that job, because diffusion only gives a net movement down a concentration gradient. Active transport is the process that moves substances against a...
Topic 4.2: Organisation
Subtopic 4.2.1: Principles of organisation
Subtopic 4.2.2: Animal tissues, organs and organ systems
4.2.2.1a - Digestive System, Enzymes and DigestionThe digestive system is an organ system: several organs work together to digest food and absorb the useful small molecules into the bloodstream. Digestion matters because large food molecules are often insoluble and too large to be absorbed. Enzymes speed up the chemical breakdown of these food m...
4.2.2.1b - Required Practical - Food TestsFood tests use chemical reagents to identify molecules in food samples. In this required practical, the tested molecules are sugars, starch, lipids and protein, using Benedict's solution, iodine solution, Sudan III stain and Biuret reagent. The results are qualitative: they tell you whether a sub...
4.2.2.1c - Required Practical - Amylase and pHThis required practical investigates how pH affects the rate at which amylase digests starch. You use iodine reagent to test whether starch is still present, and you control temperature so that pH is the factor being tested. AQA can assess the method, variables, safety, observations, rate calcula...
4.2.2.2 - The Heart and Blood VesselsThe circulatory system moves substances around the body quickly, so cells can receive oxygen and glucose and remove carbon dioxide. In humans, the heart is the muscular organ that pumps blood through blood vessels. This lesson focuses on the AQA boundary: the double circulatory system, the named...
4.2.2.3 - BloodBlood is a tissue: it contains different components that work together to transport substances, defend the body and reduce blood loss after injury. The liquid part is plasma, and suspended in it are red blood cells, white blood cells and platelets. AQA expects you to know the function of each com...
4.2.2.4 - Coronary Heart Disease and TreatmentsCoronary heart disease is a non-communicable disease that affects the blood supply to the heart muscle itself. The key GCSE idea is simple but important: narrowed coronary arteries carry less blood, so the heart muscle receives less oxygen. Treatments can improve blood flow, reduce further fatty...
4.2.2.5 - Health Issues and Disease InteractionsHealth is not just the absence of disease. In this lesson, health means physical and mental well-being, and diseases are one major cause of ill health. You will also learn how different types of disease can interact, and how AQA expects you to handle disease incidence data.
4.2.2.6 - Lifestyle Risk Factors and Non-Communicable DiseaseNon-communicable diseases are not passed from person to person, but their incidence can still change between groups of people. In this lesson, you will link lifestyle risk factors to some non-communicable diseases, then practise the data language AQA expects: sampling, correlation, graphs and num...
4.2.2.7 - CancerCancer starts when changes in cells disrupt the normal control of growth and division. The key idea is not to memorise many named cancers, but to describe how abnormal cells can form tumours, why benign and malignant tumours are different, and why risk factors affect the chance of developing cancer.
Subtopic 4.2.3: Plant tissues, organs and systems
4.2.3.1 - Plant TissuesPlants are organised: cells with similar jobs form tissues, and different tissues work together in organs. In this lesson, the main organ is the leaf. The exam focus is not just naming leaf tissues, but explaining how each tissue's structure helps it carry out its function.
4.2.3.2a - Plant Transport Organs And TranspirationRoots, stems and leaves work together as a plant organ system for transport. This lesson follows the route of water and mineral ions from the soil to the leaves, then explains how water is lost by transpiration and how the plant controls that loss. The key exam habit is to link each structure to...
4.2.3.2b - Translocation and Plant Transport DataPlants need a transport system because roots, stems and leaves do different jobs in different places. This lesson focuses on phloem and translocation, then on the data skills used when plant transport is investigated. Keep the two transport tissues separate: xylem is the water and mineral ion rou...
Topic 4.3: Infection and response
Subtopic 4.3.1: Communicable diseases
4.3.1.1 - Communicable DiseasesCommunicable diseases are diseases that can spread between organisms. In AQA Biology, this lesson is about the microorganisms that cause infectious disease, the main routes by which they spread in animals and plants, and how those routes can be interrupted. The important exam habit is to link a p...
4.3.1.2 - Viral DiseasesViral diseases are communicable diseases caused by viruses. In this AQA section, the named examples are measles, HIV and tobacco mosaic virus. For each one, you need the key symptoms or effects, the route of spread, and any control point named in the specification.
4.3.1.3 - Bacterial DiseasesBacterial diseases are infectious diseases caused by bacteria. This lesson focuses on the two named examples in this specification point: Salmonella food poisoning and gonorrhoea. The exam skill is to connect each disease to its bacterium, route of spread, symptoms and control method without drif...
4.3.1.4 - Fungal Diseases - Rose Black SpotRose black spot is the fungal disease named in this part of AQA Biology. The exam focus is not a detailed fungal life cycle: it is the visible symptoms, how the disease reduces plant growth, how it spreads, and how it can be treated or controlled. A strong answer links each symptom or treatment t...
4.3.1.5 - Protist Diseases - MalariaSome communicable diseases are caused by protists. In this specification point, the named example is malaria. The key exam idea is not the detailed biology of the malaria parasite: it is that malaria is caused by a protist pathogen, spread using a mosquito vector, and controlled by reducing mosqu...
4.3.1.6 - Human Defence SystemsPathogens can cause communicable disease only if they reach a place in the body where they can survive and reproduce. The human body therefore has two broad layers of defence: non-specific systems that reduce pathogen entry, and the immune system, which responds if pathogens get inside. This less...
4.3.1.7 - VaccinationVaccination protects against infectious disease by preparing the immune system before the real pathogen causes illness. For AQA, the core sequence is small and precise: a dead or inactive form of a pathogen is introduced, white blood cells make antibodies, and if the same pathogen enters later th...
4.3.1.8 - Antibiotics and PainkillersMedicines can help with disease in different ways. Some medicines act on the cause of a disease, while others reduce symptoms so the person feels better. In this lesson, keep the boundary precise: antibiotics act on bacterial disease, painkillers act on symptoms, and viral pathogens are not kille...
4.3.1.9 - Discovery and Development of DrugsNew medicines are not used just because a scientist has found an interesting chemical. AQA expects you to describe the route from discovery to testing: where candidate drugs may come from, what they must be tested for, and how trials reduce bias before results are accepted. The exam focus is the...
Subtopic 4.3.2: Monoclonal antibodies
4.3.2.1 - Producing Monoclonal AntibodiesThis is Biology-only Higher tier content. A monoclonal antibody is useful because every antibody molecule is the same, so it binds to one specific target. In this lesson the focus is production only: how mouse lymphocytes and tumour cells are used to make hybridoma cells, then how a single hybrid...
4.3.2.2 - Uses of Monoclonal AntibodiesMonoclonal antibodies are useful because they bind to one specific target molecule. This biology-only Higher-tier lesson is about how that specificity is used in diagnosis, laboratory testing, research and some disease treatments. The production method belongs to the previous specification point,...
Subtopic 4.3.3: Plant disease
4.3.3.1 - Detection And Identification Of Plant DiseasesPlant disease diagnosis starts with careful observation: what has changed in the plant, and where? This AQA Biology-only lesson covers the signs that can help detect plant disease, the methods used to identify the cause, and the limited plant disease and ion-deficiency examples required by the sp...
4.3.3.2 - Plant Defence ResponsesPlants cannot run away from pathogens or herbivores, so they rely on built-in defences. In this biology-only AQA GCSE Biology lesson, the important skill is to describe examples of physical and chemical plant defence responses, and to recognise the mechanical adaptations AQA lists alongside them....
Topic 4.4: Bioenergetics
Subtopic 4.4.1: Photosynthesis
4.4.1.1 - Photosynthetic ReactionPhotosynthesis is the reaction that plants and algae use to make glucose. At AQA GCSE depth, the core is not a detailed biochemical pathway: it is the reaction equation, the chemical symbols, and the idea that light transfers energy to chloroplasts. This lesson keeps the focus on those exam-ready...
4.4.1.2a - Rate of Photosynthesis and Limiting FactorsPhotosynthesis does not happen at one fixed speed. Its rate depends on conditions such as light intensity, temperature, carbon dioxide concentration and the amount of chlorophyll. This lesson focuses on explaining those effects, using rate calculations and interpreting graphs without drifting int...
4.4.1.2b - Required Practical - Light Intensity and PhotosynthesisIn this required practical, you investigate how light intensity affects the rate of photosynthesis in an aquatic plant such as pondweed. The plant produces oxygen during photosynthesis, so the rate can be estimated by counting oxygen bubbles or measured more directly by collecting the volume of g...
4.4.1.3 - Uses of Glucose from PhotosynthesisPhotosynthesis makes glucose, but a plant does not use that glucose in just one way. Some glucose is used as a fuel in respiration, while some is changed into larger molecules for storage, strength and growth. In this lesson, keep the list exact: respiration, starch, fats or oils, cellulose, and...
Subtopic 4.4.2: Respiration
4.4.2.1a - Aerobic and Anaerobic RespirationRespiration is a chemical process happening inside living cells, not the same thing as breathing. It transfers energy from glucose so cells can carry out life processes. This lesson compares aerobic and anaerobic respiration at AQA depth: oxygen use, word equations, products and the relative amou...
4.4.2.1b - Anaerobic respiration in muscles and fermentationAnaerobic respiration transfers energy without using oxygen. In this lesson, the important AQA idea is that different cells make different products when they respire anaerobically: muscle cells make lactic acid, while plant and yeast cells make ethanol and carbon dioxide. You also need to know wh...
4.4.2.2 - Response to ExerciseDuring exercise, muscle cells contract more often, so they need energy transferred by respiration at a faster rate. The body responds by moving more oxygenated blood to the muscles, but vigorous exercise can still leave the muscles short of oxygen. This lesson follows the AQA boundary for respons...
4.4.2.3 - MetabolismMetabolism is not one single reaction. It is the name for all the reactions happening in a cell or in the body, including reactions that build larger molecules and reactions that break molecules down. In AQA GCSE Biology, the key job is to link the named reactions together without drifting into d...
Topic 4.5: Homeostasis and response
Subtopic 4.5.2: The human nervous system
4.5.2.1a - The Nervous System and Reflex ArcsThe nervous system lets humans react to changes around them and coordinate behaviour. For AQA, the key idea is a fast pathway: receptors detect a stimulus, neurones carry electrical impulses to the central nervous system, and effectors bring about a response. Reflex arcs are a special case becaus...
4.5.2.1b - Required Practical - Reaction TimeIn this required practical, you investigate how a chosen factor affects human reaction time. The core skill is not just catching a ruler: it is planning a valid test, controlling variables, repeating measurements, calculating means and interpreting reaction-time data. AQA can assess the ruler-dro...
4.5.2.2 - The BrainThe brain controls complex behaviour by coordinating activity across billions of interconnected neurones. This biology-only lesson focuses on three regions that you must be able to identify and describe: the cerebral cortex, cerebellum and medulla. Higher-tier students also need to explain why in...
4.5.2.3a - The Eye and AccommodationThe eye is a sense organ that detects light and helps the nervous system form a visual response. In this biology-only AQA lesson, the main skill is to connect named eye structures with their functions, then explain how the lens changes shape to focus on near or distant objects. Vision defects and...
4.5.2.3b - Vision Defects And Their CorrectionVision depends on light rays being refracted so that they focus on the retina at the back of the eye. In myopia and hyperopia, the rays do not focus on the retina, so the image is blurred. This lesson is about the two defects, how spectacle lenses correct them, and the other correction technologi...
4.5.2.4 - Control of Body TemperatureBody temperature control is a Biology-only part of AQA GCSE Biology. The core idea is that the brain monitors body temperature, receives information from the skin, and triggers effectors that transfer more or less energy between the skin and the environment. Higher-tier students must also be able...
Subtopic 4.5.3: Hormonal coordination in humans
4.5.3.1 - Human Endocrine SystemThe endocrine system is one of the body's coordination systems. It uses chemicals called hormones, which are released from glands into the blood and carried to target organs. In this lesson, the focus is the core route: gland, hormone, blood, target organ, effect.
4.5.3.2a - Blood glucose controlBlood glucose concentration changes after eating, exercise and time between meals. The pancreas monitors and controls this concentration using hormones carried in the blood. This lesson stays with the normal control mechanism: insulin lowers blood glucose, and Higher Tier students also need gluca...
4.5.3.2b - Diabetes and Blood Glucose TreatmentsDiabetes is a disorder in which blood glucose concentration is not controlled properly. In this lesson, the focus is not the full hormone feedback loop; it is how Type 1 and Type 2 diabetes differ, how each can be treated, and how to use glucose and insulin data carefully. The key exam habit is t...
4.5.3.3a - Water, ions and urea balanceYour cells work best when the fluid around them stays within a narrow range of water and dissolved substances. This biology-only lesson explains why osmotic changes matter, how water, ions and urea leave the body, and how the kidneys help maintain water balance. Higher Tier content adds deaminati...
4.5.3.3b - Kidney Failure, Dialysis and TransplantsKidneys help keep the internal conditions of the blood within a safe range. If the kidneys fail, waste substances and excess water or ions can build up, so treatment is needed. This lesson focuses only on the two GCSE treatment routes: kidney dialysis and kidney transplant, plus how to evaluate t...
4.5.3.4 - Hormones in Human ReproductionReproductive hormones coordinate changes at puberty and help control human reproduction. This lesson covers the AQA 4.5.3.4 boundary for the natural menstrual cycle: what the named hormones do, how ovulation fits into the cycle, and what Higher Tier students need to explain from hormone-level gra...
4.5.3.5 - ContraceptionContraception means using methods to reduce the chance of pregnancy. Some methods use hormones to affect egg maturation or release, while others physically or chemically reduce the chance that sperm reach an egg or that an embryo implants. In this lesson, the key skill is evaluation: choosing use...
4.5.3.6 - Hormones to Treat InfertilityThis Higher Tier lesson is about using hormones in modern reproductive technologies to treat infertility. The key idea is that FSH and LH can be given to stimulate egg maturation, either so pregnancy may happen in the normal way or as part of IVF. Keep the boundary tight: this is not a full lesso...
4.5.3.7 - Negative feedbackThis Higher Tier lesson is about two hormones that help the body respond to changing conditions: adrenaline and thyroxine. Adrenaline prepares the body for rapid action in fear or stress, while thyroxine affects metabolic rate, growth and development. The negative-feedback example in this specifi...
Subtopic 4.5.4: Plant hormones
4.5.4.1a - Plant Hormones and TropismsPlants cannot move from place to place, but they can coordinate growth so shoots and roots grow in useful directions. This Biology-only lesson explains how plant hormones control growth responses to light and gravity. The separate practical scaffold handles investigation skills, so this lesson st...
4.5.4.1b - Required Practical - Plant ResponsesIn this biology-only required practical, you investigate how light or gravity affects the growth of newly germinated seedlings. The practical is assessed through method, variables, control setups, length measurements, accurate labelled biological drawings and conclusions from data. The plant-horm...
4.5.4.2 - Use of Plant HormonesPlant hormones are chemical messengers that control plant growth and development. In this Higher Tier biology-only lesson, the focus is how people use three plant hormones: auxins, ethene and gibberellins. This is not the Required Practical 8 method; here, you need the commercial and agricultural...
Topic 4.6: Inheritance, variation and evolution
Subtopic 4.6.1: Reproduction
4.6.1.1 - Sexual and Asexual ReproductionReproduction produces new organisms. In this part of GCSE Biology, the important comparison is whether gametes fuse and whether genetic information is mixed. The detailed stages of meiosis come next, so this lesson uses only the brief prerequisite: meiosis makes non-identical cells, while mitosis...
4.6.1.2 - MeiosisMeiosis is the cell division that makes gametes for sexual reproduction. The key GCSE idea is a number-control idea: meiosis halves the chromosome number in gametes, and fertilisation restores the full chromosome number. You need the overall sequence and outcome, not the named stages of meiosis.
4.6.1.3 - Advantages and Disadvantages of Sexual and Asexual ReproductionThis is Biology-only content. The key idea is that neither sexual nor asexual reproduction is always "better"; each has advantages in different circumstances. You need to know the named examples in the specification, but the main exam skill is applying the trade-offs to an unfamiliar organism whe...
4.6.1.4 - DNA and the GenomeDNA is the chemical genetic material in cells, and the genome is the full set of genetic material in an organism. This lesson keeps the scale clear: DNA is contained in chromosomes, genes are sections of DNA on chromosomes, and a genome is all the genetic material together. The key exam skill is...
4.6.1.5 - DNA structureDNA stores genetic information in a sequence of bases. In this biology-only lesson, the important structure is not a detailed chemical formula: it is the repeating nucleotide pattern, the sugar-phosphate strands, and how the order of bases can control the order of amino acids in a protein. Higher...
4.6.1.6a - Genetic Inheritance Terms and GametesGenetic inheritance uses a small set of precise words. They link the DNA carried on chromosomes to the alleles in gametes, the genotype an organism inherits, and the phenotype that may be expressed. This lesson builds that language and stops just before the full genetic-cross method, which is tau...
4.6.1.6b - Genetic crosses and Punnett squaresA genetic cross is a model for predicting the possible offspring from two parents. In this lesson, the cross is always a single-gene cross with two alleles, because that is the GCSE boundary for Punnett-square probability. The aim is to move confidently between a Punnett square, genotype ratios,...
4.6.1.7a - Inherited DisordersSome disorders are inherited because particular alleles are passed from parents to offspring. In this lesson, the two AQA examples are polydactyly and cystic fibrosis. The main job is to connect each disorder to the correct allele pattern: dominant for polydactyly, recessive for cystic fibrosis.
4.6.1.7b - Embryo ScreeningEmbryo screening is assessed as an interpretation and evaluation topic. You need to use information you are given, then make a balanced judgement about economic, social and ethical issues. The exam does not require a clinical method for IVF or genetic testing here; keep the focus on evidence, inh...
4.6.1.8 - Sex DeterminationHuman sex determination in this AQA GCSE Biology section is about one chromosome pair. Ordinary human body cells contain 23 pairs of chromosomes: 22 pairs control characteristics only, and one pair carries genes that determine sex. The key skill is to use a simple genetic cross to show why the ex...
Subtopic 4.6.2: Variation and evolution
4.6.2.1 - VariationIndividuals in the same population are not identical. AQA calls these differences in characteristics variation. In this lesson, the important boundary is why phenotype differs: genes, the environment during development, or both, with mutation as the original source of genetic variants.
4.6.2.2 - EvolutionEvolution is a change in the inherited characteristics of a population over time. In AQA GCSE Biology, you explain this mainly through natural selection: variants with phenotypes better suited to their environment are more likely to survive, reproduce and pass on inherited characteristics. This l...
4.6.2.3 - Selective breedingSelective breeding is a way humans change the inherited characteristics of plants and animals over many generations. It is also called artificial selection because people, not the environment, choose which organisms reproduce. In this lesson, the main job is to explain the process clearly and wei...
4.6.2.4a - Genetic Engineering ProcessGenetic engineering changes an organism's genome by adding a gene from another organism. The aim is that the added gene gives the recipient organism a desired characteristic. This lesson focuses on the process and vector use; evaluation of uses is treated in the next split lesson.
4.6.2.4b - Genetic Engineering Applications and RisksGenetic engineering can give organisms useful characteristics, but AQA is especially interested in how those uses are judged. In this lesson, the process is only a brief prerequisite: the main work is explaining applications in agriculture and medicine, then weighing possible benefits, risks and...
4.6.2.5a - Plant Cloning by Cuttings and Tissue CulturePlant cloning produces new plants with the same genetic information as the parent plant. In this biology-only AQA GCSE Biology lesson, the two plant methods are cuttings and tissue culture. The exam skill is to describe how each method produces identical plants and to explain why growers might us...
4.6.2.5b - Animal cloning and embryo transplantsAnimal cloning produces genetically identical copies of animal cells, embryos or organisms. In this biology-only lesson, the two AQA methods are embryo transplants and adult cell cloning. Both can be useful in agriculture and medicine, but both also raise risks, limitations and ethical objections.
Subtopic 4.6.3: The development of understanding of genetics and evolution
4.6.3.1 - Theory of evolutionCharles Darwin proposed the theory of evolution by natural selection after observations on a round-the-world expedition, followed by years of experimentation, discussion and links with geology and fossils. This Biology-only lesson explains the theory at AQA GCSE depth, why Darwin's ideas were gra...
4.6.3.2 - SpeciationSpeciation is the formation of new species. This Biology-only lesson links the idea of natural selection to the work of Darwin and Alfred Russel Wallace, then follows the steps by which an original population can become two different species. The key exam endpoint is precise: two populations have...
4.6.3.3 - Development of GeneticsThis biology-only topic is about how scientists built the modern idea of genes over time. The exam focus is the sequence of understanding: Mendel's plant breeding, the later observation of chromosomes, the idea that genes are on chromosomes, and the mid-20th-century work on DNA structure and gene...
4.6.3.4 - Evidence for evolutionThe theory of evolution by natural selection is now widely accepted because scientists have evidence that supports it. For this AQA point, the evidence to describe is deliberately focused: characteristics are passed on in genes, the fossil record shows organisms from the past, and antibiotic resi...
4.6.3.5 - FossilsFossils are evidence from organisms that lived millions of years ago, usually found in rocks. They do not give a perfect record of every organism that has ever lived, but they can show how much or how little organisms have changed as life developed on Earth. In this lesson, the key skills are to...
4.6.3.6 - ExtinctionExtinction is the end point for a species: there are no living individuals of that species left. In this lesson, the key GCSE skill is not to list random disasters, but to describe how a factor can reduce survival or successful breeding until a population reaches zero.
4.6.3.7 - Resistant BacteriaBacteria can evolve rapidly because they reproduce quickly. In this lesson, the key idea is natural selection in a bacterial population: a mutation can produce a strain that is not killed by an antibiotic, so that strain survives, reproduces and spreads. The lesson also covers MRSA and the ways a...
Subtopic 4.6.4: Classification of living organisms
Topic 4.7: Ecology
Subtopic 4.7.1: Adaptations, interdependence and competition
4.7.1.1 - Communities and InterdependenceEcology studies how organisms live with each other and with their environment. In this lesson, the important move is scale: a single organism is not the same as a population, a community is not the same as an ecosystem, and an ecosystem includes both living and non-living parts. Once those levels...
4.7.1.2 - Abiotic factorsAbiotic factors are the non-living conditions in an environment. In AQA GCSE Biology, the key skill is not just naming these factors, but explaining how a change in one of them could affect organisms in a given community. You should also be able to use data in charts, graphs and tables to support...
4.7.1.3 - Biotic factorsA community contains all the populations of different species living in the same habitat. A biotic factor is a living factor that can affect those populations. In this lesson, the focus is how changes in food, predators, pathogens and competition can change numbers of organisms in a community, es...
4.7.1.4 - AdaptationsOrganisms survive in different natural environments because they have features called adaptations. In this lesson, the important skill is not memorising a long list of animals and plants; it is explaining how a feature helps survival in a particular set of conditions. AQA can give you information...
Subtopic 4.7.2: Organisation of an ecosystem
4.7.2.1a - Ecosystem Levels and Food ChainsEcologists study living organisms at different scales, from one individual organism to the whole ecosystem. In this lesson, you will connect those levels to feeding relationships, food chains, sampling data and predator-prey cycles. The important thread is simple: producers make biomass, consumer...
4.7.2.1b - Required Practical - Sampling PopulationsIn Required Practical 9, you estimate the population size of a common species in a habitat and investigate how a factor affects where that species is found. The key tools are quadrats and transects, plus careful sampling so the data represent the habitat rather than the places a student happened...
4.7.2.2 - Water and carbon cyclesEcosystems keep working because materials are recycled. Carbon, water and mineral ions move between living organisms and the non-living environment, so future organisms can use the same building blocks. In this AQA lesson, the focus is the carbon cycle, the water cycle, and the role of microorgan...
4.7.2.3a - Decomposition and Decay FactorsDecomposition is the breakdown of biological material such as dead organisms, fallen leaves and waste. In AQA GCSE Biology, this Biology-only lesson focuses on how microorganisms carry out decay and how temperature, water and oxygen availability change the rate of decay. It also shows how to calc...
4.7.2.3b - Investigating Decay Using Milk pHIn this Biology-only required practical, you investigate how temperature affects the rate of decay of fresh milk. The evidence is a change in pH: as milk is broken down, acidic products form, so the pH falls. AQA's classroom method usually uses lipase to make the change fast enough to measure in...
4.7.2.4 - Impact of Environmental ChangeEnvironmental change can alter where species are found in an ecosystem and how common they are in different places. This is a Higher-tier, biology-only AQA point: the key skill is to evaluate the impact of a change when you are given suitable information, such as a table, graph, survey summary or...
Subtopic 4.7.3: Biodiversity and the effect of human interaction on ecosystems
4.7.3.1 - BiodiversityBiodiversity is about variety: how many different species are present on Earth or in a particular ecosystem. This lesson focuses on why high biodiversity makes ecosystems more stable, why humans depend on maintaining it, and how waste, deforestation and global warming can reduce it.
4.7.3.2 - Waste ManagementMore people, and a higher standard of living, usually means more resources are used and more waste is produced. This lesson is about why that matters for ecosystems: if waste and chemical materials are not handled properly, they can pollute water, air and land. AQA expects you to name precise pol...
4.7.3.3 - Land UseHumans need land for homes, roads, materials, food production and waste disposal. The GCSE Biology problem is that land used in these ways is often no longer available as habitat for wild plants and animals. This lesson focuses on the AQA land-use examples and the special case of peat bogs, where...
4.7.3.4 - DeforestationDeforestation means removing forest so the land can be used for something else. In this AQA Biology point, the focus is large-scale deforestation in tropical areas, especially to provide land for cattle, rice fields and crops grown for biofuels. The skill is not just to list these causes, but to...
4.7.3.5 - Global warmingGlobal warming means a rise in the average temperature of the Earth. For AQA GCSE Biology, the key cause to know is that levels of carbon dioxide and methane in the atmosphere are increasing, and these gases contribute to global warming. The biology in this lesson is about consequences for living...
4.7.3.6 - Maintaining biodiversityBiodiversity is affected by human activity. Some human interactions damage ecosystems and reduce biodiversity, but other interactions are designed to protect species, habitats and resources. In this lesson, the key skill is not just naming conservation methods: it is explaining how each method he...
Subtopic 4.7.4: Trophic levels in an ecosystem
4.7.4.1 - Trophic levelsTrophic levels describe the feeding positions of organisms in an ecosystem. This Biology-only lesson focuses on how to number the levels in a food chain, how to name producers and different consumers, and how decomposers feed on dead material. The important exam skill is to use the right name for...
4.7.4.2 - Pyramids of biomassA pyramid of biomass is a way to show how much living material is present at each level of a food chain. In this biology-only AQA point, the key skill is construction: given suitable data, you should be able to turn the numbers into an accurate pyramid with trophic level 1 at the bottom.
4.7.4.3 - Transfer of BiomassBiomass is transferred along a food chain when one organism eats another, but most of the biomass at one trophic level is not passed to the next. This biology-only lesson explains why pyramids of biomass get smaller higher up the food chain, how biomass is lost, and how to calculate transfer effi...
Subtopic 4.7.5: Food production
4.7.5.1 - Factors affecting food securityFood security is about whether a population has enough food. This Biology-only topic asks you to describe the main biological and environmental factors that can threaten food security, and to interpret simple population and food production statistics. The important exam skill is linking a factor...
4.7.5.2 - Farming TechniquesModern farming can increase the efficiency of food production by changing how food animals use energy and nutrients. The AQA biology-only boundary is specific: limiting movement, controlling temperature, and using high-protein foods can increase growth, but some people have ethical objections to...
4.7.5.3 - Sustainable fisheriesFish stocks in the oceans are declining, so fisheries need to be managed in a way that lets fish populations keep breeding. This Biology-only lesson focuses on two specified techniques: controlling net size and using fishing quotas. The key idea is simple but important: a fishery is sustainable o...
4.7.5.4 - Role of BiotechnologyBiotechnology uses living organisms, cells or biological processes to make useful products. In this biology-only section, AQA wants you to describe and explain how biotechnology and agriculture can help meet the demands of a growing human population. The named examples are mycoprotein from Fusari...