GCSE Biology topics

Blood vessels

Arteries, veins and capillaries — each built for its job.

Written against: AQA 8464 4.2.2.2 · Foundation and Higher

Builds on: The circulatory system — “Vessels only make sense as parts of the circulatory loop.”

Blood components

Red cells, white cells, platelets and plasma — a tissue that flows.

Written against: AQA 8464 4.2.2.3 · Foundation and Higher

Builds on: The gas exchange system · The circulatory system — “Blood is what the circulation carries.”

Pathogens & disease

The microbes that cause illness, and how they spread.

Written against: AQA 8464 4.3.1.1 · Foundation and Higher

Builds on: Unicellular organisms — “Many pathogens are the unicellular organisms you met.”

The body's defences

Skin, mucus and white blood cells holding pathogens off.

Written against: AQA 8464 4.3.1.6 · Foundation and Higher

Builds on: Pathogens & disease — “Defences only make sense once you know the threat.” · Blood components

Antibiotics & resistance

Medicines that kill bacteria — and why they are losing power.

Written against: AQA 8464 4.3.1.8 · Foundation and Higher

Builds on: Pathogens & disease — “Antibiotics target the bacteria among the pathogens.” · Natural selection

Vaccination

Training the body's defences before a real infection arrives.

Written against: AQA 8464 4.3.1.7 · Foundation and Higher

Builds on: The body's defences — “A vaccine trains the defences you've just studied.”

Cell division & growth

How one cell copies itself so a body can grow and repair.

Written against: AQA 8464 4.1.2.2 · Foundation and Higher

Builds on: DNA, genes & chromosomes · Animal cell structure — “Cell division copies the cell you dissected.”

Eukaryotic and prokaryotic cells

Animal and plant cells keep their DNA inside a nucleus; bacterial cells are far smaller and keep theirs loose, as one loop plus small rings called plasmids.

Written against: AQA 8464 4.1.1.1 · Foundation and Higher

Builds on: Animal cell structure — “A bacterial cell is compared, part by part, with the animal cell you already know.” · Unicellular organisms

Size and scale of cells

Comparing the sizes of cells and their parts using orders of magnitude, standard form and the prefixes centi, milli, micro and nano.

Written against: AQA 8464 4.1.1.1 · Foundation and Higher

Builds on: Magnification & scale — “Scale work grows out of the magnification sums from Year 7.” · Standard form: small numbers (MATH) — “Cell sizes are tiny numbers, and tiny numbers are written in standard form.” · Metric unit conversions (MATH)

Animal and plant cell structures

The parts of animal and plant cells and the job of each, now including ribosomes and mitochondria, with estimating and drawing what a light microscope shows.

Written against: AQA 8464 4.1.1.2 · Foundation and Higher

Builds on: Animal cell structure — “The animal-cell parts are the Year 7 list, with ribosomes added.” · Plant cell extras — “The plant-only parts are the same three, now tied to their functions.” · Cells & microscopy — “The required practical is the Year 7 microscope work done to exam standard.”

Specialised cells

How the build of a cell fits its job, for six named cells: sperm, nerve and muscle cells in animals; root hair, xylem and phloem cells in plants.

Written against: AQA 8464 4.1.1.3 · Foundation and Higher

Builds on: Specialised cells — “The same shape-follows-job idea, now with six named cells to explain.” · Root hair cells · Animal and plant cell structures — “You explain a specialised cell by naming which standard parts it has more or fewer of.”

Cell differentiation

How unspecialised cells turn into specialised ones as an organism develops: early in animals, throughout life in many plants.

Written against: AQA 8464 4.1.1.4 · Foundation and Higher

Builds on: Specialised cells — “Differentiation is the story of how the specialised cells you know came to be.” · Specialised cells — “You need the finished specialised cells before asking how they form.”

Light and electron microscopes

Why electron microscopes show far more than light microscopes (higher magnification and resolution), and what that revealed inside cells.

Written against: AQA 8464 4.1.1.5 · Foundation and Higher

Builds on: Cells & microscopy — “You compare the electron microscope with the light microscope you have used.”

Magnification calculations

Using and rearranging magnification = image size / real size, converting units and writing answers in standard form.

Written against: AQA 8464 4.1.1.5 · Foundation and Higher

Builds on: Magnification & scale — “The same formula as Year 7, now rearranged and with unit conversions.” · Standard form: small numbers (MATH) · Size and scale of cells

Stem cells: what they are and where they are found

Unspecialised cells that can become other cell types: in human embryos, in adult bone marrow, and in the growing tips (meristems) of plants.

Written against: AQA 8464 4.1.2.3 · Foundation and Higher

Builds on: Specialised cells · Cell differentiation — “A stem cell is a cell that has not differentiated.” · Cell division & growth

Using stem cells: benefits, risks and ethics

Possible treatments (diabetes, paralysis), therapeutic cloning, the risks and the objections, and cloning plants from meristems.

Written against: AQA 8464 4.1.2.3 · Foundation and Higher

Builds on: Stem cells: what they are and where they are found — “You weigh up a use of stem cells only after knowing what they are.”

Diffusion and what changes its rate

Particles spread from high to low concentration; the rate depends on the concentration difference, temperature and surface area. Examples: oxygen, carbon dioxide and urea.

Written against: AQA 8464 4.1.3.1 · Foundation and Higher

Builds on: Diffusion — “The Year 7 idea of diffusion, now with the three factors that set its speed.” · Diffusion (CHEM)

Surface area to volume ratio and exchange surfaces

Calculating surface area to volume ratio, why large organisms need exchange surfaces and transport systems, and what makes lungs, gut, gills, roots and leaves good at exchange.

Written against: AQA 8464 4.1.3.1 · Foundation and Higher

Builds on: Absorption in the gut — “The villi were your first exchange surface; this is the general rule behind them.” · The gas exchange system — “The alveoli are the second worked example of the same rule.” · Surface area of prisms (MATH) · Diffusion and what changes its rate — “Exchange surfaces exist to make diffusion fast enough.”

Osmosis

Water moving across a partially permeable membrane from a dilute to a concentrated solution, with percentage change in mass and graphs from the practical.

Written against: AQA 8464 4.1.3.2 · Foundation and Higher

Builds on: Osmosis — “The Year 8 idea, now measured: percentage change in mass and a graph.” · Diffusion and what changes its rate — “Osmosis is diffusion of water, so the diffusion rules apply.”

Active transport

Moving substances from low to high concentration using energy from respiration (mineral ions into root hairs, sugar from the gut), and telling it apart from diffusion and osmosis.

Written against: AQA 8464 4.1.3.3 · Foundation and Higher

Builds on: Aerobic respiration — “Active transport spends the energy that respiration releases.” · Root hair cells · Plant mineral nutrition · Diffusion and what changes its rate — “Active transport is defined as going against the direction diffusion would take.” · Osmosis

How enzymes work

Enzymes as biological catalysts with an active site of a particular shape (lock and key), and how temperature and pH change how fast they work.

Written against: AQA 8464 4.2.2.1 · Foundation and Higher

Builds on: Enzymes in digestion — “You met enzymes as digestion's tools; now you learn how the tool grips its target.” · Catalysts (CHEM) — “An enzyme is a catalyst made by a living cell.” · Acids, alkalis & pH (CHEM)

Digestive enzymes and bile

Where amylase, proteases and lipases are made, what each breaks down and into what, and how bile helps by neutralising stomach acid and breaking fat into droplets.

Written against: AQA 8464 4.2.2.1 · Foundation and Higher

Builds on: Enzymes in digestion — “The Year 8 enzyme-to-food matching, now with sites of production and products.” · Digestion & nutrition — “You need the route through the gut to place each enzyme.” · Nutrients & their jobs · How enzymes work — “Named digestive enzymes are examples of the general enzyme model.”

Food tests

Chemical tests that show which food molecules are present: Benedict's for sugars, iodine for starch, Biuret for protein. The practical also covers lipids, though the specification names no lipid test.

Written against: AQA 8464 4.2.2.1 · Foundation and Higher

Builds on: Testing a leaf for starch — “The iodine test for starch was first used on a leaf.” · Nutrients & their jobs

The heart and double circulation

The heart's chambers, the two loops (to the lungs and to the body), the named vessels joined to the heart, and natural and artificial pacemakers.

Written against: AQA 8464 4.2.2.2 · Foundation and Higher

Builds on: The circulatory system — “The Year 8 double loop, now with named chambers, vessels and the pacemaker.”

Coronary heart disease and its treatment

Fatty build-up narrowing the heart's own arteries, and weighing up stents, statins, replacement valves, transplants and artificial hearts.

Written against: AQA 8464 4.2.2.4 · Foundation and Higher

Builds on: Blood vessels — “The disease is a narrowed artery, so you need to know what an artery does.” · Energy balance & health · The heart and double circulation — “Coronary arteries and valves are parts of the heart you have just learned.”

Health and disease

Health as physical and mental well-being, communicable versus non-communicable disease, how one illness can lead to another, and reading disease data.

Written against: AQA 8464 4.2.2.5 · Foundation and Higher

Builds on: Pathogens & disease · Scatter graphs & correlation (MATH)

Lifestyle risk factors

How diet, smoking, alcohol, exercise, obesity and carcinogens raise the risk of non-communicable diseases, the difference between a risk factor and a proven cause, and the human and financial cost.

Written against: AQA 8464 4.2.2.6 · Foundation and Higher

Builds on: Effects of smoking — “Smoking is a named risk factor; you know what it does to the lungs.” · Effects of alcohol — “Alcohol is a named risk factor; you know what it does to the liver and brain.” · Energy balance & health — “Obesity as a risk factor follows from energy balance.” · Correlation is not causation (MATH) · Health and disease — “Risk factors only make sense once non-communicable disease is defined.”

Cancer

Cancer as uncontrolled cell growth and division, the difference between benign and malignant tumours, and lifestyle and genetic risk factors.

Written against: AQA 8464 4.2.2.7 · Foundation and Higher

Builds on: Cell division & growth — “Cancer is cell division with the controls lost.” · Lifestyle risk factors

Plant tissues and the leaf

The tissues of a leaf and what each is built to do: epidermis, palisade and spongy mesophyll, xylem and phloem, guard cells, and meristem at the growing tips.

Written against: AQA 8464 4.2.3.1 · Foundation and Higher

Builds on: The leaf as an organ — “The Year 8 leaf, now with every layer named.” · Tissues → organs → systems

Transpiration and stomata

Water loss from leaves, how guard cells open and close stomata, and how temperature, humidity, air movement and light change the rate.

Written against: AQA 8464 4.2.3.2 · Foundation and Higher

Builds on: Transport in plants — “Transpiration is what pulls the water up the xylem.” · The leaf as an organ — “Stomata were met as the leaf's gas doors; now they control water loss too.” · Plant tissues and the leaf — “Guard cells and stomata are named leaf tissues.”

Xylem, phloem and translocation

How root hair cells take in water and mineral ions, how xylem carries them up, and how phloem moves dissolved sugars around the plant (translocation).

Written against: AQA 8464 4.2.3.2 · Foundation and Higher

Builds on: Transport in plants — “The Year 8 two-tube story, now with how each tube is built.” · Root hair cells — “Uptake starts at the root hair cell.” · Active transport — “Mineral ions enter the root by active transport.” · Osmosis

Viral diseases: measles, HIV and tobacco mosaic virus

Symptoms, spread and control of three named viral diseases, two human and one of plants.

Written against: AQA 8464 4.3.1.2 · Foundation and Higher

Builds on: Pathogens & disease — “Each named disease is a worked example of how a virus spreads and harms.”

Bacterial diseases: salmonella and gonorrhoea

Symptoms, spread and control of two named bacterial diseases.

Written against: AQA 8464 4.3.1.3 · Foundation and Higher

Builds on: Pathogens & disease — “Each named disease is a worked example of how bacteria spread and harm.”

Fungal disease: rose black spot

A named fungal disease of plants: what it looks like, how it spreads and how it is treated.

Written against: AQA 8464 4.3.1.4 · Foundation and Higher

Builds on: Pathogens & disease — “A worked example of a fungal pathogen.”

Protist disease: malaria

Malaria: caused by a protist, carried by mosquitoes, and controlled by stopping mosquitoes breeding and biting.

Written against: AQA 8464 4.3.1.5 · Foundation and Higher

Builds on: Pathogens & disease — “A worked example of a protist pathogen and a vector.”

Where medicines come from

Traditional sources of drugs (foxglove, willow, the Penicillium mould) and how most are made by chemists today.

Written against: AQA 8464 4.3.1.9 · Foundation and Higher

Builds on: Microbes: friend and foe

Testing new medicines

How a new drug is checked for safety, effectiveness and dose: laboratory tests, then clinical trials, placebos, double-blind trials and peer review.

Written against: AQA 8464 4.3.1.9 · Foundation and Higher

Builds on: Where medicines come from

The photosynthesis reaction

The word equation, the chemical symbols for the four substances, and photosynthesis as a reaction that takes in energy from light.

Written against: AQA 8464 4.4.1.1 · Foundation and Higher

Builds on: Photosynthesis — the word equation — “The Year 7 word equation, now with symbols and energy.” · Exothermic & endothermic (CHEM) — “Endothermic is the chemistry word for a reaction that takes energy in.” · Exothermic and endothermic reactions (CHEM)

Rate of photosynthesis and limiting factors

How temperature, light, carbon dioxide and chlorophyll change the rate, how to measure it, and reading graphs with one limiting factor.

Written against: AQA 8464 4.4.1.2 · Foundation and Higher

Builds on: Limiting factors for photosynthesis — “The Year 8 limiting factors, now measured and graphed.” · The photosynthesis reaction — “You can only talk about the rate of a reaction you can write down.”

Interacting limiting factors and the inverse square law

Graphs with two or three factors, light intensity falling with the square of distance, and the economics of heating and lighting a greenhouse.

Written against: AQA 8464 4.4.1.2 · Higher only

Builds on: Inverse proportion (MATH) — “The inverse square law is inverse proportion with a square in it.” · Rate of photosynthesis and limiting factors — “Several factors at once builds on reading one factor at a time.” · Proportion formulae (MATH)

How plants use glucose

The five things a plant does with the glucose it makes: respire it, store it as starch, store it as fat or oil, build cellulose, and make amino acids using nitrates.

Written against: AQA 8464 4.4.1.3 · Foundation and Higher

Builds on: Photosynthesis — the word equation — “Glucose is the product of photosynthesis.” · Plant mineral nutrition — “Nitrates from the soil are what turn glucose into protein.” · Testing a leaf for starch · The photosynthesis reaction — “This is what happens next to the product of the reaction.”

Aerobic respiration

Respiration as an energy-releasing reaction running all the time in every living cell: the equation with symbols, and what the energy is used for.

Written against: AQA 8464 4.4.2.1 · Foundation and Higher

Builds on: Aerobic respiration — “The Year 8 word equation, now with symbols and energy.” · Exothermic & endothermic (CHEM) — “Exothermic is the chemistry word for a reaction that gives energy out.” · Exothermic and endothermic reactions (CHEM)

Anaerobic respiration and fermentation

Respiration without oxygen: lactic acid in muscles, ethanol and carbon dioxide in yeast and plants, why it releases less energy, and its use in bread and brewing.

Written against: AQA 8464 4.4.2.1 · Foundation and Higher

Builds on: Anaerobic respiration — “The Year 9 topic, now with the yeast equation and the comparison.” · Microbes: friend and foe · Aerobic respiration — “Anaerobic respiration is defined by comparison with aerobic.”

The body's response to exercise

Why heart rate, breathing rate and breath volume rise in exercise, and how lactic acid, oxygen debt and muscle fatigue follow when oxygen runs short. *Higher tier only (was 4.4.2.2b, Oxygen debt and the liver):* What happens to lactic acid afterwards (carried to the liver and turned back into glucose) and the exact meaning of oxygen debt.

Written against: AQA 8464 4.4.2.2 · Foundation and Higher, with some Higher-only content

Builds on: Heart rate & exercise — “You measured the pulse rising; now you explain every change.” · Exercise & fitness · Anaerobic respiration and fermentation — “Fatigue is explained by anaerobic respiration in muscle.”

Metabolism

Metabolism as the sum of all reactions in a cell or body: building and breaking down carbohydrates, proteins and lipids, and making urea from excess protein.

Written against: AQA 8464 4.4.2.3 · Foundation and Higher

Builds on: Nutrients & their jobs · Aerobic respiration — “Respiration supplies the energy for building molecules.” · How plants use glucose — “The plant's uses of glucose are examples of metabolism.” · How enzymes work — “Every metabolic reaction is controlled by an enzyme.”

Fossils & the evidence

How rock records the slow rewriting of species.

Written against: AQA 8464 4.6.3.2 · Foundation and Higher

Builds on: Extinction · Darwin's theory — “Fossils are the evidence Darwin's theory predicts.” · Natural selection — the evidence

Selective breeding

Choosing which living things breed to steer their traits.

Written against: AQA 8464 4.6.2.3 · Foundation and Higher

Builds on: Variation — “Selective breeding steers variation on purpose.” · Natural selection · Variation and mutation

Reflexes & the nervous system

Fast, automatic responses that skip conscious thought. Read the full explainer →

Written against: AQA 8464 4.5.2 · Foundation and Higher

Builds on: Tissues → organs → systems — “The nervous system is another organ system to map.” · Specialised cells · Homeostasis — “The nervous system is one of the body's two control systems.”

Natural selection — the evidence

How variation plus time rewrites species.

Written against: AQA 8464 4.6.3.1 · Foundation and Higher

Builds on: Ecosystems & food webs · Natural selection — “The evidence deepens the selection idea.” · Inheritance & variation · Evolution by natural selection — “Evidence is evidence for the theory just stated.”

Introduction to genetic modification

Moving a gene from one organism to another, on purpose.

Written against: AQA 8464 4.6.2.4 · Foundation and Higher

Builds on: DNA, genes & chromosomes — “Editing genes needs you to know what a gene is.” · Selective breeding · DNA and the genome

Classification & the tree of life

Grouping living things by shared features and shared ancestry.

Written against: AQA 8464 4.6.4 · Foundation and Higher

Builds on: Darwin's theory · Identification keys — “Classification formalises the keys you've used.” · Evolution by natural selection · Eukaryotic and prokaryotic cells

Homeostasis

Keeping conditions inside the body steady (blood glucose, temperature, water) using receptors, coordination centres and effectors.

Written against: AQA 8464 4.5.1 · Foundation and Higher

Builds on: How enzymes work — “Steady conditions matter because enzymes only work well in a narrow range.”

The reflex arc and reaction time

The three nerve cells of a reflex arc and the gaps between them, why reflexes matter, and measuring reaction time.

Written against: AQA 8464 4.5.2 · Foundation and Higher

Builds on: Reflexes & the nervous system — “You know reflexes are fast; now you trace the route that makes them fast.”

The endocrine system

Glands that release hormones into the blood, how hormonal control compares with nervous control, the pituitary as master gland, and where six glands are.

Written against: AQA 8464 4.5.3.1 · Foundation and Higher

Builds on: The circulatory system · Homeostasis — “Hormones are the chemical half of the body's control systems.” · Reflexes & the nervous system

Blood glucose, insulin and diabetes

How the pancreas uses insulin to lower blood glucose, and how Type 1 and Type 2 diabetes differ in cause and treatment. *Higher tier only (was 4.5.3.2b, Glucagon and negative feedback):* How glucagon raises blood glucose and works with insulin in a negative feedback loop.

Written against: AQA 8464 4.5.3.2 · Foundation and Higher, with some Higher-only content

Builds on: Energy balance & health · The endocrine system — “Insulin is a hormone from a gland you have located.” · Homeostasis — “Blood glucose is one of the three named conditions kept steady.”

Hormones in reproduction and the menstrual cycle

Oestrogen and testosterone at puberty, and the jobs of FSH, LH, oestrogen and progesterone in the menstrual cycle. *Higher tier only (was 4.5.3.3b, How the menstrual-cycle hormones interact):* How the four hormones switch each other on and off through the cycle, and reading graphs of their levels.

Written against: AQA 8464 4.5.3.3 · Foundation and Higher, with some Higher-only content

Builds on: The menstrual cycle — “The Year 9 cycle, now with the hormones that drive each stage.” · Puberty & adolescence · The endocrine system — “Reproductive hormones are endocrine hormones.”

Contraception

Hormonal and non-hormonal ways of preventing pregnancy, how each works, and weighing them up.

Written against: AQA 8464 4.5.3.4 · Foundation and Higher

Builds on: Gametes & fertilisation — “Every method works by stopping sperm meeting egg, or an egg maturing.” · Hormones in reproduction and the menstrual cycle — “Hormonal methods work by interfering with FSH and progesterone.”

Hormones to treat infertility

Fertility drugs and IVF: how FSH and LH are used, the steps of IVF, and its costs and risks.

Written against: AQA 8464 4.5.3.5 · Higher only

Builds on: Gametes & fertilisation — “IVF is fertilisation done outside the body.” · Hormones in reproduction and the menstrual cycle — “The treatment uses the two hormones that mature and release eggs.”

Adrenaline, thyroxine and negative feedback

What adrenaline and thyroxine do, and how thyroxine is held steady by negative feedback.

Written against: AQA 8464 4.5.3.6 · Higher only

Builds on: The endocrine system — “Both are hormones from glands you have located.” · Blood glucose, insulin and diabetes · Metabolism

Sexual and asexual reproduction

Two parents and mixed genetic information versus one parent and identical offspring (clones), and which type of cell division each involves.

Written against: AQA 8464 4.6.1.1 · Foundation and Higher

Builds on: Reproduction — “The Year 8 contrast, now explained by what happens to the genetic information.” · Gametes & fertilisation · Cell division & growth — “Asexual reproduction is mitosis and nothing else.”

Meiosis

The cell division that makes gametes: four cells, each with half the chromosomes and all genetically different; fertilisation restores the full number.

Written against: AQA 8464 4.6.1.2 · Foundation and Higher

Builds on: Gametes & fertilisation — “Gametes carry half-sets; meiosis is how the halving happens.” · Cell division & growth — “Meiosis is learned by contrast with mitosis.” · DNA, genes & chromosomes — “Halving only makes sense once chromosomes come in pairs.”

DNA and the genome

DNA as a double helix, a gene as a stretch of DNA that codes for one protein, the genome as all of an organism's genetic material, and why reading the human genome matters.

Written against: AQA 8464 4.6.1.3 · Foundation and Higher

Builds on: DNA, genes & chromosomes — “The Year 9 nesting of DNA, gene and chromosome, now with structure and purpose.” · Polymers: long-chain molecules (CHEM)

The language of genetics

Ten terms that inheritance questions rely on: gamete, chromosome, gene, allele, dominant, recessive, homozygous, heterozygous, genotype and phenotype.

Written against: AQA 8464 4.6.1.4 · Foundation and Higher

Builds on: Inheritance & variation — “You know offspring take after both parents; these are the words for how.” · DNA, genes & chromosomes — “An allele is a version of a gene.” · DNA and the genome — “Genotype and phenotype rest on a gene coding for a protein.”

Genetic crosses and Punnett squares

Completing and reading Punnett squares and family trees, and giving outcomes as ratios and probabilities. Higher tier also builds the cross from scratch.

Written against: AQA 8464 4.6.1.4 · Foundation and Higher, with some Higher-only content

Builds on: Probability of single events (MATH) — “A cross predicts a probability, not a certainty.” · Ratio notation (MATH) · Sample space diagrams (MATH) · The language of genetics — “A cross cannot be read without the vocabulary.”

Inherited disorders

Polydactyly (dominant allele) and cystic fibrosis (recessive allele), and the arguments around embryo screening.

Written against: AQA 8464 4.6.1.5 · Foundation and Higher

Builds on: Genetic crosses and Punnett squares — “Each disorder is worked through as a genetic cross.”

Sex determination

Humans have 23 pairs of chromosomes; one pair decides sex (XX female, XY male), shown with a genetic cross.

Written against: AQA 8464 4.6.1.6 · Foundation and Higher

Builds on: DNA, genes & chromosomes · Genetic crosses and Punnett squares — “Sex inheritance is shown with the same cross diagram.”

Variation and mutation

Differences within a species come from genes, environment or both; all new variants start as mutations, most of which change nothing.

Written against: AQA 8464 4.6.2.1 · Foundation and Higher

Builds on: Variation — “The Year 9 causes of variation, now with mutation as the source.” · Inheritance & variation · DNA and the genome — “A mutation is a change in the DNA.”

Evolution by natural selection

Evolution as change in inherited characteristics of a population over time, from simple life over three billion years ago, and how new species form.

Written against: AQA 8464 4.6.2.2 · Foundation and Higher

Builds on: Natural selection — “The Year 9 steps of natural selection, now carried through to new species.” · Darwin's theory · Variation and mutation — “Selection needs variation to act on.”

The steps of genetic engineering

The process itself: enzymes cut out the gene, a carrier (a plasmid or virus) takes it into the target cells, done early in development.

Written against: AQA 8464 4.6.2.4 · Higher only

Builds on: Introduction to genetic modification — “The steps explain how the transfer you already know about is done.” · Eukaryotic and prokaryotic cells — “The usual carrier is a bacterial plasmid.” · How enzymes work

Antibiotic-resistant bacteria

How resistant strains such as MRSA arise by mutation and selection, and the three ways to slow them down.

Written against: AQA 8464 4.6.3.4 · Foundation and Higher

Builds on: Antibiotics & resistance — “The Year 9 link between overuse and resistance, now explained as evolution.” · Evolution by natural selection — “Resistance is natural selection on a fast clock.”

Communities, interdependence and competition

The levels from single organism to ecosystem, what plants and animals compete for, how species depend on each other, and what makes a community stable.

Written against: AQA 8464 4.7.1.1 · Foundation and Higher

Builds on: Competition & interdependence — “The Year 9 topic, now with the levels of an ecosystem and the idea of stability.” · Ecosystems & food webs

Abiotic factors

The seven non-living factors that affect a community (light, temperature, moisture, soil, wind, carbon dioxide, oxygen) and predicting the effect of a change.

Written against: AQA 8464 4.7.1.2 · Foundation and Higher

Builds on: Habitats & adaptation · Communities, interdependence and competition — “Factors act on the community you have just defined.”

Biotic factors

The four living factors that affect a community (food, new predators, new pathogens, being out-competed) and predicting the effect of a change.

Written against: AQA 8464 4.7.1.3 · Foundation and Higher

Builds on: Competition & interdependence — “Competition is one of the named biotic factors.” · Predator–prey cycles · Communities, interdependence and competition — “Factors act on the community you have just defined.”

Adaptations and extremophiles

Structural, behavioural and functional adaptations, and organisms that live in extreme heat, pressure or salt.

Written against: AQA 8464 4.7.1.4 · Foundation and Higher

Builds on: Habitats & adaptation — “The Year 7 idea, now sorted into three kinds and pushed to extremes.”

Sampling with quadrats and transects

Measuring how many of a species live in a habitat and where, using quadrats and transects, with mean, median and mode.

Written against: AQA 8464 4.7.2.1 · Foundation and Higher

Builds on: Sampling with quadrats — “The Year 8 quadrat method, now with transects and a factor to investigate.” · Averages & range (MATH) — “Counts are summarised with mean, median and mode.” · Abiotic factors · Sampling & bias (MATH)

Waste and pollution

How a growing population produces more waste, and how pollution of water, air and land reduces biodiversity.

Written against: AQA 8464 4.7.3.2 · Foundation and Higher

Builds on: Human impact on ecosystems — “The Year 9 overview of human impact, now sorted by water, air and land.” · Biodiversity — “Pollution is judged by what it does to biodiversity.” · Pollutants from burning fuels (CHEM)

Land use and peat bogs

How building, quarrying, farming and dumping take land from other species, and why destroying peat bogs costs both habitat and carbon.

Written against: AQA 8464 4.7.3.3 · Foundation and Higher

Builds on: Human impact on ecosystems — “Land use was one of the named human impacts; peat is the worked example.” · The carbon cycle · Biodiversity — “Land use is judged by what it does to biodiversity.”

Maintaining biodiversity

Five kinds of programme that protect biodiversity (breeding, habitat protection, hedgerows, cutting deforestation and emissions, recycling) and the pressures against them.

Written against: AQA 8464 4.7.3.6 · Foundation and Higher

Builds on: Conservation — “The Year 9 conservation topic, now with five named methods to evaluate.” · Biodiversity — “You protect biodiversity once you know why it matters.”