AQA GCSE Biology: grade by grade

Every skill, from the first marks to the top grade. For each grade you also need the skills for the grades below it. Tick them off in the app's Notes section.

Grade 3

Grade 3 checklist (PDF)

Name eukaryotic and prokaryotic cells Animal and plant cells are eukaryotic; bacterial cells are prokaryotic. Eukaryotes and prokaryotes
Name the parts of an animal cell Nucleus, cytoplasm, cell membrane, mitochondria and ribosomes. Animal and plant cells
Name the extra structures in plant cells Chloroplasts, a permanent vacuole filled with cell sap, and a cell wall made of cellulose. Animal and plant cells
Name specialised animal and plant cells Sperm, nerve and muscle cells in animals; root hair, xylem and phloem cells in plants. Cell specialisation
State what cell differentiation is Differentiation is the process by which a cell becomes specialised for a particular function. Cell differentiation
State what magnification means How many times bigger the image is than the real object. Microscopy
State how bacteria reproduce Bacteria multiply by simple cell division called binary fission. Culturing microorganisms
State where chromosomes are found In the nucleus of a cell. Chromosomes
State what mitosis produces Two genetically identical cells. Mitosis and the cell cycle
State what a stem cell is An undifferentiated cell that can make more cells of the same type and can differentiate into other types of cell. Stem cells
Define diffusion The net movement of particles from an area of higher concentration to an area of lower concentration. Diffusion
Define osmosis The diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane. Osmosis
State what active transport is The movement of substances from a more dilute solution to a more concentrated solution, against a concentration gradient. Active transport
Put the levels of organisation in order From smallest to largest: cell → tissue → organ → organ system → organism. Principles of organisation
Name the organs of the digestive system Mouth and salivary glands, oesophagus, stomach, liver, gall bladder, pancreas, small intestine and large intestine. The human digestive system
Name the three types of blood vessel Arteries carry blood away from the heart, veins carry blood back to the heart, and capillaries link them inside tissues. The heart and blood vessels
Name the four components of blood Plasma, red blood cells, white blood cells and platelets. Blood
Name the vessels that supply heart muscle The coronary arteries supply the heart muscle with oxygenated blood. Coronary heart disease
Define health Health is the state of physical and mental well-being. Health issues
Define a risk factor A factor linked to an increased rate of a disease, such as part of a person's lifestyle or a substance in their body or environment. Lifestyle and non-communicable diseases
Define cancer Cancer is the result of changes in cells that lead to uncontrolled growth and division. Cancer
Name the tissues in a leaf Upper and lower epidermis, palisade mesophyll, spongy mesophyll, xylem and phloem, with guard cells around the stomata. Plant tissues
Name the parts of the plant transport system The roots, stem and leaves form an organ system; xylem carries water and phloem carries sugars. Plant organ system
Define a pathogen A pathogen is a microorganism that causes infectious (communicable) disease. Communicable (infectious) diseases
Name the four types of pathogen Viruses, bacteria, fungi and protists; they can infect both animals and plants. Communicable (infectious) diseases
Name viral diseases of humans and plants Measles and HIV in humans; tobacco mosaic virus (TMV) in plants. Viral diseases
Name two bacterial diseases Salmonella food poisoning and gonorrhoea, a sexually transmitted disease. Bacterial diseases
Name a fungal disease of plants Rose black spot is a fungal disease of roses. Fungal diseases
Name a disease caused by a protist Malaria is caused by a single-celled protist. Protist diseases
Name the body's non-specific defences The skin, the nose, the trachea and bronchi, and the stomach. Human defence systems
State what a vaccine contains Small quantities of a dead or inactive form of a pathogen. Vaccination
State what antibiotics do Antibiotics, such as penicillin, kill infective bacteria inside the body, curing bacterial diseases. Antibiotics and painkillers
State what painkillers do Painkillers treat the symptoms of a disease but do not kill pathogens. Antibiotics and painkillers
Match drugs to their original sources Digitalis from foxgloves, aspirin from willow, and penicillin from Penicillium mould (discovered by Alexander Fleming). Discovery and development of drugs
Name physical defences of plants Cellulose cell walls, a tough waxy cuticle on leaves, and layers of dead cells on stems (e.g. bark) that fall off. Plant defence responses
Write the word equation for photosynthesis carbon dioxide + water → glucose + oxygen, with light written above the arrow. Photosynthetic reaction
State where photosynthesis takes place In the chloroplasts of plant and algal cells, where chlorophyll absorbs light. Photosynthetic reaction
Name the factors affecting photosynthesis rate Temperature, light intensity, carbon dioxide concentration and the amount of chlorophyll. Rate of photosynthesis
List the five uses of glucose Respiration, starch for storage, fats or oils for storage, cellulose for cell walls, and amino acids for proteins. Uses of glucose from photosynthesis
State why organisms need energy For chemical reactions that build larger molecules, for movement and for keeping warm. Aerobic and anaerobic respiration
Write the word equation for aerobic respiration glucose + oxygen → carbon dioxide + water. Aerobic and anaerobic respiration
State how exercise changes heart and breathing Heart rate, breathing rate and breath volume all increase. Response to exercise
Define metabolism Metabolism is the sum of all the reactions in a cell or the body. Metabolism
Define homeostasis Regulating the internal conditions of a cell or organism to keep them at the optimum, in response to internal and external changes. Homeostasis
Name conditions controlled by homeostasis In humans: blood glucose concentration, body temperature and water levels. Homeostasis
State what the nervous system does It lets you react to your surroundings and coordinates your behaviour. Structure and function
Label the three main brain regions Identify the cerebral cortex, cerebellum and medulla on a diagram of the brain. The brain
Label the main parts of the eye Cornea, iris, pupil, lens, ciliary muscles, suspensory ligaments, retina, optic nerve and sclera. The eye
State normal core body temperature About 37 °C, the optimum for the body's enzymes. Control of body temperature
Define a hormone A chemical secreted by a gland directly into the bloodstream, which carries it to a target organ. Human endocrine system
Name the organ that controls blood glucose The pancreas monitors and controls blood glucose concentration. Control of blood glucose concentration
List ways water leaves the body From the lungs when you breathe out, from the skin in sweat, and from the kidneys in urine. Maintaining water and nitrogen balance
Name the main male and female hormones Testosterone from the testes; oestrogen from the ovaries. Hormones in human reproduction
Name hormonal and non-hormonal contraceptive methods E.g. the pill, implant, condom, diaphragm, IUD, spermicide, abstinence and sterilisation. Contraception
Define phototropism and gravitropism Phototropism is a growth response to light; gravitropism (geotropism) is a growth response to gravity. Control and coordination
Name the gametes in animals and plants Animals: sperm and egg cells. Flowering plants: pollen and egg cells. Sexual and asexual reproduction
State how many parents each type needs Sexual reproduction needs two parents; asexual reproduction needs only one. Sexual and asexual reproduction
State where and why meiosis happens Cells in the reproductive organs divide by meiosis to form gametes. Meiosis
State where DNA is found The genetic material in the nucleus is a chemical called DNA, contained in chromosomes. DNA and the genome
Define dominant and recessive alleles A dominant allele is expressed even with one copy; a recessive allele is expressed only with two copies. Genetic inheritance
Describe polydactyly and cystic fibrosis Polydactyly is having extra fingers or toes; cystic fibrosis is a disorder of cell membranes. Inherited disorders
State the number of chromosome pairs Ordinary human body cells contain 23 pairs of chromosomes. Sex determination
Define variation Differences in the characteristics of individuals in a population. Variation
Define evolution A change in the inherited characteristics of a population over time through natural selection. Evolution
Define selective breeding Humans breeding plants and animals for particular genetic characteristics. Selective breeding
Define a clone An organism that is genetically identical to another. Cloning
Name the scientist behind natural selection Charles Darwin developed the theory of evolution by natural selection. Theory of evolution
State what Wallace independently proposed Wallace independently proposed the theory of evolution by natural selection. Speciation
Name Mendel and the plants he used Gregor Mendel carried out breeding experiments on pea plants in the mid-19th century. The understanding of genetics
State that evolution is widely accepted The theory of evolution by natural selection is now widely accepted. Evidence for evolution
Define a fossil The remains of organisms from millions of years ago, which are found in rocks. Fossils
Define extinction A species is extinct when there are no remaining individuals of that species still alive. Extinction
Name an antibiotic-resistant bacterium MRSA is resistant to antibiotics. Resistant bacteria
List the Linnaean groups in order Kingdom, phylum, class, order, family, genus, species. Classification of living organisms
Define population, community, habitat and ecosystem A population is one species in a habitat, a community is all the populations there, and an ecosystem is the community interacting with the non-living environment. Communities
Define an abiotic factor A non-living factor in the environment that can affect a community. Abiotic factors
Define a biotic factor A living factor, such as another organism, that can affect a community. Biotic factors
Define an adaptation A feature that helps an organism survive in the conditions where it normally lives. Adaptations
Name producers and consumers in a food chain The producer comes first, then the primary, secondary and tertiary consumers. Levels of organisation
State that materials are recycled in ecosystems Materials cycle through the living and non-living parts of an ecosystem, providing the building blocks for new organisms. How materials are cycled
State what decomposers do Microorganisms such as bacteria and fungi break down dead organisms and waste. Decomposition
Define biodiversity The variety of all the different species of organisms on Earth, or within an ecosystem. Biodiversity
Name sources of water, air and land pollution Water: sewage, fertiliser, toxic chemicals. Air: smoke, acidic gases. Land: landfill, toxic chemicals. Waste management
Name ways humans use land Building, quarrying, farming and dumping waste. Land use
Define deforestation Cutting down large areas of forest so the land can be used for something else. Deforestation
Name two gases that contribute to global warming Carbon dioxide and methane. Global warming
Name programmes that protect biodiversity Breeding programmes, protecting rare habitats, hedgerows and field margins, reducing deforestation and carbon dioxide emissions, and recycling. Maintaining biodiversity
Number the trophic levels in a food chain Level 1 is the producer, level 2 the primary consumer, and so on along the chain. Trophic levels
Define biomass The mass of living material, often given per unit area, e.g. in g/m². Pyramids of biomass
Define food security Having enough food to feed a population. Factors affecting food security
State that fish stocks are declining Fish are being caught faster than they can reproduce (overfishing), so numbers in the oceans are falling. Sustainable fisheries
Name a food made from a fungus Mycoprotein, a protein-rich food made from the fungus Fusarium. Role of biotechnology

Grade 4

Grade 4 checklist (PDF)

Describe the structure of a bacterial cell Cytoplasm and a cell membrane inside a cell wall, a single loop of DNA not in a nucleus, and often plasmids. Eukaryotes and prokaryotes
State the function of each structure e.g. mitochondria are where aerobic respiration happens; ribosomes are where proteins are made. Animal and plant cells
State the function of each specialised cell e.g. a nerve cell carries electrical impulses; phloem carries dissolved sugars. Cell specialisation
Say when animal and plant cells differentiate Most animal cells differentiate at an early stage; many plant cells can differentiate throughout life. Cell differentiation
Calculate the total magnification of a microscope Multiply the eyepiece lens magnification by the objective lens magnification, e.g. ×10 and ×40 give ×400. Microscopy
Compare light and electron microscopes Electron microscopes have much higher magnification and resolution; light microscopes can show living cells in colour. Microscopy
Name two ways of growing bacteria In a nutrient broth solution, or as colonies on an agar gel plate. Culturing microorganisms
Describe what chromosomes are made of Chromosomes are made of DNA, and each chromosome carries a large number of genes. Chromosomes
State the chromosome number in human cells Body cells have 23 pairs (46 in total); sperm and egg cells have 23 single chromosomes. Chromosomes
Name the three stages of the cell cycle Growth and DNA replication; mitosis; division of the cytoplasm and cell membrane. Mitosis and the cell cycle
Name where stem cells are found In embryos, in adult bone marrow, and in the meristems of plants. Stem cells
Give examples of diffusion in living things Oxygen and carbon dioxide in gas exchange; urea from cells into the blood plasma. Diffusion
Predict the direction of water movement Water moves from the more dilute solution into the more concentrated solution. Osmosis
State where the energy comes from Active transport needs energy from respiration. Active transport
Define tissue, organ and organ system A tissue is a group of cells with a similar structure and function, an organ is a group of tissues working together, and an organ system is a group of organs working together. Principles of organisation
State what each digestive enzyme produces Amylase turns starch into sugars, proteases turn proteins into amino acids, and lipases turn lipids into fatty acids and glycerol. The human digestive system
Describe the food tests and positive results Benedict's turns from blue to brick red when heated with sugar, iodine from orange-brown to blue-black with starch, and Biuret from blue to purple with protein. The human digestive system
Label the heart's chambers and main vessels Right and left atria and ventricles, the vena cava, pulmonary artery, pulmonary vein, aorta and coronary arteries. The heart and blood vessels
State the function of each component Plasma transports dissolved substances, red blood cells carry oxygen, white blood cells defend against pathogens and platelets help the blood clot. Blood
Describe what happens in coronary heart disease Layers of fatty material build up inside the coronary arteries and narrow them. Coronary heart disease
Tell communicable and non-communicable diseases apart Communicable diseases are caused by pathogens and can spread; non-communicable diseases cannot be passed from one person to another. Health issues
Match risk factors to the diseases they affect Diet, smoking and lack of exercise → cardiovascular disease; obesity → type 2 diabetes; alcohol → liver and brain; smoking → lung disease and lung cancer; carcinogens → cancer. Lifestyle and non-communicable diseases
Describe a benign tumour A growth of abnormal cells contained in one area, usually within a membrane, that does not invade other parts of the body. Cancer
Label a leaf cross-section From top to bottom: waxy cuticle, upper epidermis, palisade mesophyll, spongy mesophyll with air spaces and veins, lower epidermis with stomata. Plant tissues
State where meristem tissue is found At the growing tips of shoots and roots, where cells divide to make new cells. Plant tissues
Define transpiration and translocation Transpiration is the loss of water vapour from the leaves; translocation is the movement of dissolved sugars through the phloem. Plant organ system
Describe how pathogens are spread By direct contact, by water and by air, and also in food, in body fluids and by vectors. Communicable (infectious) diseases
Describe the symptoms and spread of measles Fever and a red skin rash; it is spread by breathing in droplets from coughs and sneezes. Viral diseases
Describe how HIV is spread By sexual contact or by exchange of body fluids such as blood, e.g. when drug users share needles. Viral diseases
Give the symptoms of Salmonella food poisoning Fever, abdominal cramps, vomiting and diarrhoea, caused by the bacteria and the toxins they secrete. Bacterial diseases
Give the symptoms of gonorrhoea A thick yellow or green discharge from the vagina or penis, and pain on urinating. Bacterial diseases
Describe the symptoms of rose black spot Purple or black spots develop on the leaves, which often turn yellow and drop early. Fungal diseases
State how rose black spot is spread It is spread in the environment by water (e.g. splashing rain) or by wind. Fungal diseases
Describe the main symptom of malaria Recurrent episodes of fever (the fever keeps coming back); malaria can be fatal. Protist diseases
Identify the vector of malaria Mosquitoes carry the protist and pass it to people when they bite them. Protist diseases
Describe how each defence stops pathogens Skin is a barrier; mucus traps pathogens; cilia move the mucus away; stomach acid kills pathogens. Human defence systems
Name three ways white blood cells defend Phagocytosis, producing antibodies and producing antitoxins. Human defence systems
Describe what a vaccine makes the body do It stimulates white blood cells to produce antibodies against the pathogen. Vaccination
Explain why antibiotics don't treat viral diseases Antibiotics kill bacteria but cannot kill viruses. Antibiotics and painkillers
State what new drugs are tested for Toxicity (is it harmful?), efficacy (does it work?) and dose (how much should be given?). Discovery and development of drugs
List signs that a plant is diseased Stunted growth, spots on leaves, areas of decay (rot), growths, malformed stems or leaves, discolouration and the presence of pests. Detection and identification of plant diseases
Name chemical defences of plants Antibacterial chemicals, and poisons that deter herbivores. Plant defence responses
Name mechanical adaptations of plants Thorns and hairs, leaves that droop or curl when touched, and mimicry. Plant defence responses
Recognise the formulae of the four substances Carbon dioxide is CO₂, water is H₂O, glucose is C₆H₁₂O₆ and oxygen is O₂. Photosynthetic reaction
Explain what a limiting factor is The factor in shortest supply, which stops the rate of photosynthesis increasing; raising it raises the rate. Rate of photosynthesis
Describe the light intensity required practical Put pondweed at different distances from a lamp and count the oxygen bubbles, or measure the volume of oxygen, in a set time. Rate of photosynthesis
State what cellulose is used for Cellulose strengthens the cell wall of plant cells. Uses of glucose from photosynthesis
Name where plants store starch and oils Starch is stored in leaves, roots and tubers such as potatoes; many seeds store oils. Uses of glucose from photosynthesis
Write the anaerobic equations for muscles and yeast In muscles: glucose → lactic acid. In plant cells and yeast: glucose → ethanol + carbon dioxide. Aerobic and anaerobic respiration
Explain why heart and breathing rates increase To supply the muscles with more oxygenated blood for the extra respiration needed to contract. Response to exercise
Give examples of metabolic reactions For example respiration, making starch, glycogen or cellulose from glucose, making lipids and proteins, and making urea. Metabolism
Name the three parts of a control system Receptors, coordination centres and effectors. Homeostasis
Name the parts of the CNS The central nervous system (CNS) is the brain and spinal cord. Structure and function
Put the reflex arc in order Stimulus → receptor → sensory neurone → relay neurone → motor neurone → effector → response. Structure and function
State the function of each region Cerebral cortex: consciousness, intelligence, memory, language. Cerebellum: coordinates muscles. Medulla: unconscious activities. The brain
State the function of each part E.g. the retina contains light receptors; the optic nerve carries impulses to the brain. The eye
Name where temperature is monitored The thermoregulatory centre in the brain, which has receptors sensitive to blood temperature. Control of body temperature
List the responses to overheating Vasodilation and more sweat produced by sweat glands. Control of body temperature
Locate the main endocrine glands Pituitary, thyroid, adrenal glands, pancreas, ovaries and testes on a body diagram. Human endocrine system
Match glands to their hormones E.g. pancreas: insulin; adrenal glands: adrenaline; testes: testosterone. Human endocrine system
Describe how insulin lowers blood glucose Insulin makes glucose move from the blood into cells; liver and muscle cells store it as glycogen. Control of blood glucose concentration
Describe how the kidneys produce urine Filtration of the blood, then selective reabsorption of useful substances such as glucose, some ions and water. Maintaining water and nitrogen balance
Define ovulation The release of a mature egg from an ovary, about every 28 days. Hormones in human reproduction
Explain how barrier methods work Condoms and diaphragms stop sperm reaching the egg. Contraception
Describe how shoots and roots respond Shoots grow towards light and against gravity; roots grow downwards, in the direction of gravity. Control and coordination
Define sexual reproduction The joining (fusion) of a male gamete and a female gamete. Sexual and asexual reproduction
State how many gametes meiosis produces The cell divides twice to form four gametes. Meiosis
Give an advantage of asexual reproduction Only one parent is needed, so there is no need to find a mate. Pros and cons of sexual and asexual reproduction
Give an advantage of sexual reproduction It produces variation in the offspring. Pros and cons of sexual and asexual reproduction
Describe the structure of DNA simply DNA is a polymer made up of two strands forming a double helix. DNA and the genome
Put nucleus, chromosome and gene in size order Nucleus (largest), then chromosome, then gene (a small section of DNA on a chromosome). DNA and the genome
Name the four bases in DNA The four bases are A, C, G and T. DNA structure
Use genotype, phenotype, homozygous and heterozygous correctly Genotype is the alleles present, phenotype is the characteristic; homozygous means the same alleles, heterozygous different. Genetic inheritance
State which allele causes each disorder Polydactyly is caused by a dominant allele; cystic fibrosis by a recessive allele. Inherited disorders
Give the sex chromosomes of each sex Females are XX; males are XY. Sex determination
Classify causes of variation Genetic (genes inherited), environmental (conditions of development) or a combination of both. Variation
State when simple life first developed All species evolved from simple life forms that first developed more than three billion years ago. Evolution
Give examples of chosen characteristics Disease resistance in crops, more meat or milk, gentle dogs, large or unusual flowers. Selective breeding
Define genetic engineering Modifying an organism's genome by introducing a gene from another organism to give a desired characteristic. Genetic engineering
Give examples of genetic engineering Bacteria that make human insulin; crops resistant to disease, insects or herbicides; bigger, better fruits. Genetic engineering
Describe taking cuttings Gardeners cut a piece from a parent plant and grow it into a new, identical plant. Cloning
Describe how Darwin developed his theory Observations on a round-the-world expedition, backed by experimentation and discussion with other scientists. Theory of evolution
Recall what Wallace is best known for His work on warning colouration in animals and his theory of speciation. Speciation
State Mendel's key observation The inheritance of each characteristic is determined by 'units' that are passed on to descendants unchanged. The understanding of genetics
Name two types of evidence for evolution The fossil record and the evolution of antibiotic resistance in bacteria. Evidence for evolution
Describe three ways fossils form Parts that have not decayed, parts replaced by minerals, and preserved traces such as footprints. Fossils
List the causes of extinction Environmental change, new predators, new diseases, new competitors and catastrophic events. Extinction
State ways to reduce antibiotic resistance Don't prescribe antibiotics for viral or non-serious infections, complete the course, and restrict their use in farming. Resistant bacteria
Use binomial names An organism's scientific name is its genus followed by its species, e.g. Homo sapiens. Classification of living organisms
List what plants compete for Light and space, and water and mineral ions from the soil. Communities
List what animals compete for Food, mates and territory. Communities
List the abiotic factors in the specification Light intensity, temperature, moisture level, soil pH and mineral content, wind intensity and direction, carbon dioxide (plants) and oxygen (aquatic animals). Abiotic factors
List the four biotic factors in the specification Availability of food, new predators arriving, new pathogens, and one species outcompeting another. Biotic factors
Classify adaptations as structural, behavioural or functional Structural means body features, behavioural means what it does, and functional means processes inside the body. Adaptations
State why food chains start with producers Producers (green plants and algae) make glucose by photosynthesis, so they produce the biomass for the rest of the chain. Levels of organisation
Calculate a mean, median and mode Mean = total ÷ number of values; median = middle value when in order; mode = most common value. Levels of organisation
Name the processes in the water cycle Evaporation, transpiration, condensation, precipitation, and water draining back into rivers and seas. How materials are cycled
Name the three factors affecting decay rate Temperature, water (moisture) and the availability of oxygen. Decomposition
Name human activities that reduce biodiversity For example pollution, building, farming, deforestation and destroying peat bogs. Biodiversity
Explain why more waste is produced The human population is growing rapidly and the standard of living is rising, so more resources are used. Waste management
Explain how land use reduces biodiversity Habitats are destroyed, so there is less space, food and shelter for other plants and animals. Land use
Give reasons for tropical deforestation To provide land for cattle and rice fields, and to grow crops for biofuels. Deforestation
Give human activities that increase these gases Burning fossil fuels, deforestation and destroying peat add carbon dioxide; cattle, rice fields and landfill add methane. Global warming
Describe producers, herbivores and carnivores Producers make their own food, herbivores eat plants or algae, and carnivores eat other animals. Trophic levels
Identify the trophic levels on a pyramid Trophic level 1 (the producers) is always the bottom bar. Pyramids of biomass
State the typical transfer percentages Producers transfer about 1% of the incident light energy for photosynthesis; about 10% of biomass passes to the next level. Transfer of biomass
List factors that threaten food security Rising birth rate, changing diets, new pests and pathogens, environmental change, the cost of agricultural inputs and conflicts. Factors affecting food security
Name ways to make animal farming more efficient Limit the animals' movement, control the temperature of their surroundings, and feed them high-protein food. Farming techniques
Name two methods to conserve fish stocks Controlling net (mesh) size and introducing fishing quotas. Sustainable fisheries
Describe how mycoprotein is produced Fusarium is grown on glucose syrup in aerobic conditions, then the biomass is harvested and purified. Role of biotechnology

Grade 5

Grade 5 checklist (PDF)

Compare prokaryotic and eukaryotic cells Say what both have (cell membrane, cytoplasm, ribosomes) and how they differ, above all whether the DNA is enclosed in a nucleus. Eukaryotes and prokaryotes
Convert between mm, µm and nm Multiply by 1000 for each step down (mm → µm → nm) and divide by 1000 for each step up. Eukaryotes and prokaryotes
Explain why some plant cells lack chloroplasts Cells that receive no light, such as root cells, cannot photosynthesise, so they have no chloroplasts. Animal and plant cells
Describe the adaptations of each specialised cell e.g. a sperm cell has a tail, many mitochondria and enzymes in its head. Cell specialisation
State what cell division does in adults In mature animals, cell division is mainly for repair and replacement. Cell differentiation
Use magnification = image size ÷ real size Rearrange the equation to find the magnification, the image size or the real size. Microscopy
Prepare a slide and focus a microscope Thin sample, stain, coverslip; start on the lowest power and focus with the coarse, then the fine, focus. Microscopy
Describe aseptic technique for preparing a culture Sterilise the dishes, media and inoculating loop, tape the lid, store the dish upside down and incubate at 25 °C. Culturing microorganisms
Put cell, nucleus, chromosome and gene in order Largest to smallest: cell, nucleus, chromosome, gene. Chromosomes
Describe what happens in each stage The cell grows, copies its sub-cellular structures and DNA, divides its nucleus, then splits in two. Mitosis and the cell cycle
State why mitosis is important For the growth and development of multicellular organisms, and to repair and replace cells. Mitosis and the cell cycle
Recognise where mitosis is happening e.g. a root tip growing, a cut healing, an embryo developing. Mitosis and the cell cycle
Compare embryonic and adult stem cells Embryonic stem cells can become most types of human cell; adult bone marrow stem cells form fewer types, including blood cells. Stem cells
Describe uses of meristem cloning Making clones quickly and cheaply, saving rare species, and producing crops with useful features. Stem cells
Explain the factors that affect the rate A bigger concentration gradient, a higher temperature and a larger surface area all increase the rate of diffusion. Diffusion
Describe the osmosis required practical Weigh pieces of plant tissue, leave them in a range of concentrations, then reweigh them. Osmosis
Calculate percentage change in mass Change in mass ÷ starting mass × 100; a loss in mass gives a negative answer. Osmosis
Describe two examples of active transport Mineral ions from the soil into root hair cells; sugar from the gut into the blood. Active transport
Classify a structure by its level For example, a red blood cell is a cell, blood is a tissue, the heart is an organ and the circulatory system is an organ system. Principles of organisation
Recall where each digestive enzyme is made Amylase in the salivary glands, pancreas and small intestine; proteases in the stomach, pancreas and small intestine; lipases in the pancreas and small intestine. The human digestive system
Describe the double circulatory system The right ventricle pumps blood to the lungs and the left ventricle pumps blood around the rest of the body. The heart and blood vessels
Describe the role of the pacemaker A group of cells in the right atrium controls the natural resting heart rate; an artificial pacemaker is an electrical device that corrects an irregular heart rate. The heart and blood vessels
Identify blood cells in a photo or diagram Red blood cells are biconcave discs with no nucleus, white blood cells are larger with a nucleus, and platelets are tiny fragments. Blood
List substances transported by the plasma Carbon dioxide, urea, soluble products of digestion such as glucose and amino acids, hormones and antibodies. Blood
Describe how stents and statins treat CHD A stent holds the coronary artery open; statins lower blood cholesterol, which slows the build-up of fatty material. Coronary heart disease
Describe treatments for faulty valves and heart failure Faulty valves are replaced with biological or mechanical valves; heart failure can be treated with a donor heart (or heart and lungs) or, occasionally, an artificial heart. Coronary heart disease
Give factors other than disease affecting health Diet, stress and life situations can have a big effect on both physical and mental health. Health issues
Describe effects of smoking and alcohol in pregnancy Both can harm the unborn baby, e.g. smoking can cause low birth weight and alcohol can damage the baby's brain development. Lifestyle and non-communicable diseases
Describe malignant tumours and secondary tumours Malignant tumour cells are cancers: they invade neighbouring tissues and spread in the blood to form secondary tumours. Cancer
Give lifestyle risk factors for cancer For example smoking (lung cancer), obesity (e.g. bowel cancer), too much UV light (skin cancer) and some viral infections (e.g. cervical cancer). Cancer
State the function of each leaf tissue Epidermis covers the leaf, palisade does most photosynthesis, spongy mesophyll lets gases diffuse, xylem carries water and phloem carries sugars. Plant tissues
Describe how root hair cells absorb substances They take up water by osmosis and mineral ions by active transport, helped by their large surface area. Plant organ system
Compare the structure of xylem and phloem Xylem is hollow tubes strengthened by lignin; phloem is tubes of elongated cells with pores in the end walls. Plant organ system
Explain how bacteria and viruses make you ill Both reproduce rapidly in the body; bacteria release toxins that damage tissues, and viruses reproduce inside cells and damage them. Communicable (infectious) diseases
Describe ways to reduce the spread of disease Hygiene, isolating infected individuals, destroying or controlling vectors, and vaccination. Communicable (infectious) diseases
Describe how measles and HIV are controlled Measles: vaccinating young children; HIV: condoms, not sharing needles and antiretroviral drugs. Viral diseases
Describe how each disease is spread Salmonella: bacteria swallowed in food or on food prepared in unhygienic conditions; gonorrhoea: sexual contact. Bacterial diseases
Describe how the spread of each is controlled Vaccinating poultry and hygienic food preparation for Salmonella; antibiotics and condoms for gonorrhoea. Bacterial diseases
Describe how rose black spot is treated Use fungicides and/or remove and destroy the affected leaves. Fungal diseases
Describe how the spread of malaria is controlled Stop mosquitoes breeding, and use mosquito nets to avoid being bitten. Protist diseases
Describe phagocytosis A white blood cell engulfs a pathogen and digests it. Human defence systems
Explain how vaccination prevents illness If the live pathogen enters later, white blood cells quickly make the correct antibodies and destroy it before it causes illness. Vaccination
Explain why specific antibiotics are needed Different antibiotics kill different bacteria, so the antibiotic must match the bacterium causing the disease. Antibiotics and painkillers
Describe preclinical testing The drug is tested in a laboratory on cells, tissues and live animals before any people take it. Discovery and development of drugs
Describe the stages of clinical trials Very low doses are given first to check safety; further trials on patients find the optimum dose. Discovery and development of drugs
Define monoclonal antibodies Identical antibodies produced from a single clone of cells, specific to one binding site on one protein antigen. Producing monoclonal antibodies
Name the cells that make a hybridoma A mouse lymphocyte (which makes the antibody) combined with a tumour cell (which divides rapidly). Producing monoclonal antibodies
List four uses of monoclonal antibodies Diagnosis (e.g. pregnancy tests), laboratory tests on blood, locating molecules in research, and treating diseases such as cancer. Uses of monoclonal antibodies
Describe ways to identify a plant disease Use a gardening manual or website, take the plant to a laboratory, or use a testing kit containing monoclonal antibodies. Detection and identification of plant diseases
Give examples of plant pathogens and pests Tobacco mosaic virus (a virus), rose black spot (a fungus) and aphids (insects). Detection and identification of plant diseases
Explain how physical barriers stop pathogens They are barriers that pathogens cannot easily get through, and dead cells take pathogens with them when they fall off. Plant defence responses
Explain why photosynthesis is endothermic Energy is transferred from the environment to the chloroplasts by light, so the reaction takes in energy. Photosynthetic reaction
State where the reactants come from Carbon dioxide diffuses into the leaf from the air through the stomata; water is absorbed by the roots and carried up in the xylem. Photosynthetic reaction
Explain the effect of temperature The rate rises up to an optimum temperature, then falls quickly because the enzymes that control photosynthesis denature. Rate of photosynthesis
Explain a one-factor rate graph Where the line rises the factor on the x-axis is limiting; where it levels off another factor has become limiting. Rate of photosynthesis
Describe how glucose reaches storage organs Sugars made in the leaves are carried in solution in the phloem to where they are used or stored. Uses of glucose from photosynthesis
Describe respiration as a continuous exothermic reaction It happens all the time in living cells and transfers energy to the surroundings, supplying the energy for living processes. Aerobic and anaerobic respiration
Describe fermentation and its uses Anaerobic respiration in yeast makes ethanol and carbon dioxide, which are used to make alcoholic drinks and bread. Aerobic and anaerobic respiration
Explain when muscles respire anaerobically When oxygen cannot be supplied fast enough for aerobic respiration alone, as in vigorous exercise. Response to exercise
Calculate changes from exercise data Work out increases, percentage changes and recovery times from tables and graphs of heart rate or breathing rate. Response to exercise
Name the building blocks of large molecules Carbohydrates are made from sugars, proteins from amino acids, and lipids from glycerol and fatty acids. Metabolism
State how a lipid molecule forms One molecule of glycerol joins with three molecules of fatty acids. Metabolism
Explain why homeostasis is important It keeps conditions at the optimum for enzyme action and all cell functions. Homeostasis
Describe the job of each part Receptors detect stimuli, coordination centres process the information, and effectors (muscles or glands) bring about a response. Homeostasis
Explain why reflex actions are fast They are automatic and do not involve the conscious part of the brain. Structure and function
Describe the ruler-drop reaction time practical Catch a dropped ruler, record the distance it fell and convert it to a reaction time. Structure and function
Describe how brain regions have been mapped Studying patients with brain damage, electrically stimulating the brain, and MRI scanning. The brain
Describe how the pupil changes with light The pupil widens in dim light to let more light in and narrows in bright light. The eye
List the responses to being too cold Vasoconstriction, sweating stops, and skeletal muscles contract (shivering). Control of body temperature
Compare hormonal and nervous control Hormones travel in the blood and are slower but longer-lasting; nerve impulses are fast and short-lived. Human endocrine system
Compare the causes of Type 1 and 2 Type 1: the pancreas does not make enough insulin. Type 2: body cells stop responding to insulin. Control of blood glucose concentration
Describe treatments for each type of diabetes Type 1: insulin injections. Type 2: a carbohydrate-controlled diet and an exercise regime. Control of blood glucose concentration
Explain why cell water content must be controlled If cells gain or lose too much water by osmosis, they do not function efficiently. Maintaining water and nitrogen balance
Describe the basic principles of dialysis Blood flows past a partially permeable membrane; urea and excess ions diffuse into the dialysis fluid. Maintaining water and nitrogen balance
State the roles of the four cycle hormones FSH matures an egg, LH triggers its release, and oestrogen and progesterone maintain the uterus lining. Hormones in human reproduction
Explain how hormonal methods work The pill inhibits FSH so no eggs mature; progesterone implants stop eggs maturing and being released. Contraception
Describe how IUDs and spermicides work IUDs prevent an embryo implanting or release a hormone; spermicides kill or disable sperm. Contraception
Name the hormones in fertility drugs FSH and LH. Hormones to treat infertility
Describe how a fertility drug works FSH and LH make eggs mature and be released, so the woman may become pregnant in the normal way. Hormones to treat infertility
State the effects of adrenaline It increases heart rate and boosts delivery of oxygen and glucose to the brain and muscles. Negative feedback
State the role of thyroxine It stimulates the basal metabolic rate and is important in growth and development. Negative feedback
Describe the seedling growth practical Grow seedlings with light from one side, or on their side, and record both lengths and direction of growth. Control and coordination
Give uses of auxins As weed killers, as rooting powders, and for promoting growth in tissue culture. Use of plant hormones
Describe how ethene is used for fruit It controls the ripening of fruit during storage and transport. Use of plant hormones
Name the cell division each type uses Gametes are made by meiosis; asexual reproduction involves only mitosis. Sexual and asexual reproduction
Describe what happens in meiosis The genetic information is copied, then the cell divides twice to give four genetically different gametes, each with a single set of chromosomes. Meiosis
Give chromosome numbers in body cells and gametes A human body cell has 46 chromosomes (23 pairs) and a human gamete has 23. Meiosis
Explain why variation helps a species survive If the environment changes, some individuals are likely to have characteristics that help them survive, by natural selection. Pros and cons of sexual and asexual reproduction
Define gene and genome A gene is a small section of DNA on a chromosome; the genome is all of an organism's genetic material. DNA and the genome
Describe the structure of a nucleotide A common sugar and a phosphate group, with one of four bases attached to the sugar. DNA structure
Describe DNA as a polymer of nucleotides Long strands of alternating sugar and phosphate sections, with a base attached to each sugar. DNA structure
Complete a Punnett square Put each parent's gametes on the outside and combine one allele from each in every box. Genetic inheritance
Give cross outcomes as ratios or probabilities For example 3 : 1, or a probability of 0.25, 25%, ¼ or 1 in 4. Genetic inheritance
Explain what a carrier is A heterozygous person with one recessive allele who does not have the disorder but can pass it on. Inherited disorders
State what the other 22 pairs do 22 pairs control characteristics only; one pair carries the genes that determine sex. Sex determination
Draw a genetic cross for sex XX × XY in a Punnett square gives XX, XX, XY, XY. Sex determination
Give examples of each cause Blood group is genetic, a scar is environmental, and body mass depends on both. Variation
State that populations show genetic variation There is usually extensive genetic variation within a population of a species. Variation
List the steps of natural selection Variation, competition, the best suited survive and reproduce, alleles passed on, alleles become more common. Evolution
Describe the steps of selective breeding Choose parents with the characteristic, breed them, select the best offspring, and repeat over many generations. Selective breeding
State what GM crops are Crops whose genes have been modified by genetic engineering; they generally give increased yields. Genetic engineering
Describe tissue culture and its uses Small groups of cells from part of a plant are grown into identical plants, to preserve rare species or for nurseries. Cloning
Describe Darwin's theory Variation exists; the individuals most suited to the environment are more likely to survive to breed and pass on their characteristics. Theory of evolution
Describe how Wallace influenced Darwin Their joint writings in 1858 prompted Darwin to publish On the Origin of Species in 1859. Speciation
Define a species A group of organisms that can interbreed to produce fertile offspring. Speciation
Put the development of gene theory in order Mendel's units, chromosomes seen in cell division, units linked to chromosomes, then the structure of DNA. The understanding of genetics
Explain why genes support Darwin's theory It has been shown that characteristics are passed on to offspring in genes, which explains how they are inherited. Evidence for evolution
Explain why some remains do not decay One or more of the conditions needed for decay (such as oxygen, warmth or moisture) are absent. Fossils
Give examples of catastrophic events Massive volcanic eruptions or collisions with asteroids. Extinction
Explain why bacteria evolve rapidly They reproduce at a fast rate, so there are many generations in a short time. Resistant bacteria
Describe how Linnaeus classified organisms Into groups depending on their structure and characteristics. Classification of living organisms
Name the three domains Archaea, bacteria and eukaryota. Classification of living organisms
Explain what interdependence means Each species depends on others for food, shelter, pollination or seed dispersal, so removing one species can affect the whole community. Communities
Describe a trend in abiotic data State how one variable changes as the other changes, quoting values from the table or graph. Abiotic factors
Explain the effect of food availability More food means more organisms survive and breed, so the population grows; less food has the opposite effect. Biotic factors
Define an extremophile and give an example An organism that lives in extreme conditions of temperature, pressure or salt concentration, e.g. bacteria in deep sea vents. Adaptations
Describe using quadrats to estimate population size Place quadrats randomly, count the organisms, find the mean per quadrat, then scale up to the whole area. Levels of organisation
Name processes that add or remove carbon dioxide Photosynthesis removes carbon dioxide from the air; respiration and combustion release it. How materials are cycled
Describe how compost and biogas are produced Waste decays in warm, moist, well-aerated heaps to make compost; anaerobic decay in a biogas generator makes methane. Decomposition
Name environmental changes that affect distribution Temperature, availability of water and the composition of atmospheric gases. Impact of environmental change
Explain why biodiversity matters to humans The future of humans relies on it, e.g. for food, materials, medicines and stable ecosystems. Biodiversity
Explain how pollution reduces biodiversity Pollution kills plants and animals, so fewer species survive in the area. Waste management
State why peat bogs are destroyed Peat is dug up to produce garden compost. Land use
Explain how deforestation reduces biodiversity Forest habitats are destroyed and replaced by grazing land or one crop, so many species are lost. Deforestation
Describe biological consequences of global warming Habitat loss as sea levels rise, changes in distribution and migration, and loss of biodiversity. Global warming
Explain how each programme helps biodiversity Say what the programme does and which species or habitats it protects. Maintaining biodiversity
Define an apex predator A carnivore with no predators. Trophic levels
Describe the shape of a pyramid of biomass Each bar is smaller than the one below, because biomass decreases at each trophic level. Pyramids of biomass
Describe how biomass is lost between levels Parts not eaten, egestion in faeces, carbon dioxide and water from respiration, and urea and water in urine. Transfer of biomass
Explain how pests and pathogens threaten food supplies They destroy crops or kill farm animals, so less food is produced. Factors affecting food security
Explain why high-protein food increases growth Protein is digested into amino acids, which animals use to make the proteins needed for growth. Farming techniques
Explain why fish stocks must be maintained If too few fish are left to breed, the species may disappear altogether in some areas. Sustainable fisheries
Describe how GM bacteria produce insulin Bacteria given the human insulin gene are grown in large numbers, and the insulin is harvested and purified. Role of biotechnology

Grade 6

Grade 6 checklist (PDF)

Write cell sizes in standard form Use 1 µm = 10⁻⁶ m and 1 nm = 10⁻⁹ m, e.g. 4 µm = 4 × 10⁻⁶ m. Eukaryotes and prokaryotes
Link a cell's structures to its function e.g. a cell that needs a lot of energy has many mitochondria for respiration. Animal and plant cells
Explain how each adaptation helps the cell Give the feature and what it does, e.g. the root hair gives a large surface area for absorbing water. Cell specialisation
Explain the importance of cell differentiation It produces the different specialised cells a multicellular organism needs to carry out different functions. Cell differentiation
Convert units in magnification calculations Put the image size and the real size in the same unit, usually µm, before dividing. Microscopy
Explain the reason for each aseptic step e.g. flaming the inoculating loop kills microorganisms on it, so the culture is not contaminated. Culturing microorganisms
Calculate the area of a clear zone Use πr², halving the diameter to find the radius. Culturing microorganisms
Explain why body cell chromosomes are paired One chromosome of each pair came from each parent, in the egg and the sperm. Chromosomes
Link genes to proteins A gene is a small section of DNA that codes for a particular protein. Chromosomes
Describe therapeutic cloning and its advantage An embryo is made with the same genes as the patient, so its stem cells are not rejected. Stem cells
Calculate surface area to volume ratios Work out the total surface area and the volume, then write the ratio as x : 1. Diffusion
Explain how exchange surfaces are adapted Large surface area, thin membrane, good blood supply and ventilation, e.g. alveoli and villi. Diffusion
Calculate a rate of change in mass Change in mass ÷ time, e.g. in g per minute. Osmosis
Explain gains and losses in mass Tissue gains mass when the solution is more dilute than the cell contents, and loses mass when it is more concentrated. Osmosis
Explain osmosis in animal and plant cells Animal cells can burst in water or shrivel in concentrated solutions; a plant cell wall stops the cell bursting. Osmosis
Compare diffusion, osmosis and active transport Compare what moves, which way it moves relative to the concentration gradient, and whether energy is needed. Active transport
Explain why root hair cells have many mitochondria More respiration releases more energy for the active transport of mineral ions. Active transport
Explain why a structure is an organ Say that it is made of several different tissues that work together to carry out a specific function. Principles of organisation
Explain enzyme action using lock and key The substrate fits the specifically shaped active site, so each enzyme catalyses only one reaction. The human digestive system
Explain how bile speeds up fat digestion Bile is alkaline, so it neutralises stomach acid, and it emulsifies fat into small droplets with a larger surface area for lipase. The human digestive system
Explain how blood vessels suit their functions Arteries have thick muscular, elastic walls for high pressure, veins have valves, and capillary walls are one cell thick for diffusion. The heart and blood vessels
Calculate the rate of blood flow Rate of blood flow = volume of blood ÷ time, e.g. in cm³ per minute. The heart and blood vessels
Explain how red blood cells are adapted A biconcave shape gives a large surface area, and having no nucleus leaves more room for haemoglobin, which carries oxygen. Blood
Describe how white blood cells defend the body They engulf pathogens (phagocytosis), produce antibodies and produce antitoxins. Blood
Explain how CHD damages the heart muscle Less blood flows through the narrowed coronary arteries, so the heart muscle gets less oxygen for respiration. Coronary heart disease
Explain the consequences of a faulty valve A valve that does not open fully or that leaks makes the heart pump blood less efficiently, so less oxygen reaches the body. Coronary heart disease
Describe how different diseases can interact Immune defects increase infections, viruses can trigger cancers, immune reactions can trigger allergies, and severe physical illness can lead to depression. Health issues
Calculate and interpret values from disease data Read values from tables and graphs, calculate rates per 1000 people or percentages, and describe trends. Health issues
Describe a correlation shown in a scatter diagram Say whether the correlation is positive or negative and quote data from the graph. Lifestyle and non-communicable diseases
Discuss human and financial costs of disease Consider suffering and early death as well as treatment costs and lost work, for individuals, communities, nations and the world. Lifestyle and non-communicable diseases
Explain how a secondary tumour forms Cells break off a malignant tumour, travel in the blood to another part of the body and divide there to form a new tumour. Cancer
Explain genetic risk factors for cancer Some people inherit alleles, such as faulty BRCA alleles, that increase their risk of certain cancers. Cancer
Explain how the mesophyll layers are adapted Palisade cells are packed with chloroplasts near the top of the leaf; spongy mesophyll has air spaces for gases to diffuse through. Plant tissues
Describe what guard cells and stomata do Guard cells open and close the stomata to control gas exchange and water loss. Plant tissues
Explain factors affecting the rate of transpiration Higher temperature, lower humidity, more air movement and higher light intensity all increase the rate. Plant organ system
Calculate the rate of transpiration Rate = volume (or mass) of water lost or taken up ÷ time, e.g. from a potometer. Plant organ system
Explain how a control method stops spread Link the method to the route, e.g. washing hands removes pathogens, so they are not passed on by direct contact. Communicable (infectious) diseases
Explain why TMV reduces plant growth The discoloured parts of the leaves have less chlorophyll, so there is less photosynthesis and less glucose for growth. Viral diseases
Explain why gonorrhoea is harder to treat now Many strains are resistant to penicillin, so penicillin no longer kills them and other antibiotics must be used. Bacterial diseases
Explain how vaccinating poultry protects people Vaccinated chickens are not infected, so their meat and eggs are less likely to carry the bacteria. Bacterial diseases
Explain why black spot reduces growth Spotted, yellow and fallen leaves mean less photosynthesis, so less glucose is made for growth. Fungal diseases
Explain how each control method reduces spread Fewer mosquitoes, or fewer bites, means the protist is passed to fewer people. Protist diseases
Explain how antibodies and antitoxins work Antibodies bind to specific antigens on pathogens; antitoxins bind to the toxins made by bacteria and neutralise them. Human defence systems
Explain how vaccination reduces spread in populations If most people are immune, the pathogen is unlikely to reach unvaccinated people, so it spreads much less. Vaccination
Explain why antiviral drugs are hard to develop Viruses reproduce inside body cells, so drugs that kill them are likely to damage body tissues too. Antibiotics and painkillers
Explain why a placebo is used A placebo contains no drug, so comparing the two groups shows whether the drug itself has an effect. Discovery and development of drugs
Explain why results are peer reviewed Other experts check the method, results and conclusions before publication, so false or biased claims are less likely to be published. Discovery and development of drugs
Describe how monoclonal antibodies are produced Stimulate mouse lymphocytes, combine them with tumour cells, clone a single hybridoma cell, then collect and purify the antibody. Producing monoclonal antibodies
Explain how a pregnancy test works Antibodies bind to the hormone hCG in urine, so coloured beads collect at the test line only if hCG is present. Uses of monoclonal antibodies
Explain the control line in a pregnancy test Fixed antibodies there bind to the mobile antibodies, so a line shows that the test has worked. Uses of monoclonal antibodies
Explain the effect of nitrate deficiency Nitrate ions are needed for protein synthesis, so without them growth is stunted. Detection and identification of plant diseases
Explain the effect of magnesium deficiency Magnesium ions are needed to make chlorophyll, so leaves turn yellow (chlorosis) and photosynthesis falls. Detection and identification of plant diseases
Explain how poisons and mechanical adaptations deter animals They make the plant harmful, painful or unappealing to eat, so animals eat less of it. Plant defence responses
Explain the results of a leaf starch test Only parts of a leaf that had light and chlorophyll made glucose, which was stored as starch and turns iodine solution blue-black. Photosynthetic reaction
Explain why plants store starch, not glucose Starch is insoluble, so it does not affect the movement of water by osmosis and it stays inside the cells. Uses of glucose from photosynthesis
Explain why plants need nitrate ions Plants use glucose and nitrate ions to make amino acids, which are joined to make proteins. Uses of glucose from photosynthesis
Compare aerobic and anaerobic respiration Compare the need for oxygen, the products and the amount of energy transferred. Aerobic and anaerobic respiration
Explain muscle fatigue in long exercise Lactic acid builds up from anaerobic respiration, and over long vigorous exercise muscles stop contracting efficiently. Response to exercise
Explain why metabolism needs respiration and enzymes Building new molecules uses energy transferred by respiration, and each reaction is controlled by enzymes. Metabolism
Describe what happens to excess protein Excess proteins are broken down to form urea, which is excreted. Metabolism
Apply the control system to new contexts Pick out the stimulus, receptor, coordination centre, effector and response in an unfamiliar example. Homeostasis
Explain how impulses cross a synapse A chemical is released, diffuses across the gap and binds to receptors on the next neurone, starting a new impulse. Structure and function
Explain how neurones are adapted Long axons carry impulses a long way, branched endings connect to many neurones, and a fatty sheath speeds impulses up. Structure and function
Predict the effect of damage to a region Link the damaged region to its function and describe the likely effect on the person. The brain
Explain why brain disorders are hard to treat The brain is complex and delicate, so it is hard to reach one area without damaging others. The brain
Explain accommodation for near and distant objects Ciliary muscles contract or relax, suspensory ligaments slacken or tighten, and the lens changes shape. The eye
Describe myopia and hyperopia and their correction Short sight: light focuses in front of the retina, concave lens. Long sight: behind the retina, convex lens. The eye
Explain how sweating and vasodilation cool you Both transfer more energy from the skin to the environment. Control of body temperature
Explain why the pituitary is the 'master gland' Its hormones act on other glands, stimulating them to release their own hormones. Human endocrine system
Interpret blood glucose graphs Describe and explain the rise and fall of glucose after a meal, with and without diabetes. Control of blood glucose concentration
Evaluate dialysis and kidney transplants Weigh up time, diet, cost, rejection risk and donor shortages. Maintaining water and nitrogen balance
Interpret hormone graphs of the menstrual cycle Match each hormone's peak to events such as ovulation and the build-up of the uterus lining. Hormones in human reproduction
Evaluate different methods of contraception Compare effectiveness, side effects, STI protection, convenience and whether the method is reversible. Contraception
Describe the main stages of IVF Give FSH and LH, collect eggs, fertilise them in the lab, then insert one or two embryos. Hormones to treat infertility
Define negative feedback A change away from normal triggers a response that reverses the change, returning the level to normal. Negative feedback
Explain phototropism using auxin Auxin moves to the shaded side, where cells elongate faster, so the shoot bends towards the light. Control and coordination
Give uses of gibberellins Ending seed dormancy, promoting flowering and increasing fruit size. Use of plant hormones
Explain why sexually produced offspring vary Genetic information from two parents is mixed, so each offspring gets a different combination of alleles. Sexual and asexual reproduction
Explain why asexual offspring are clones There is no fusion of gametes and no mixing of genetic information, and only mitosis is involved. Sexual and asexual reproduction
Explain why gametes have half the chromosomes So that fertilisation restores the normal number of chromosomes. Meiosis
Describe development after fertilisation The new cell divides by mitosis, the number of cells increases and the cells differentiate as the embryo develops. Meiosis
Explain why asexual reproduction is efficient No time or energy is spent finding a mate, and many identical offspring can be produced quickly when conditions are favourable. Pros and cons of sexual and asexual reproduction
Name organisms that reproduce both ways Malarial parasites, many fungi, and plants such as strawberries and daffodils. Pros and cons of sexual and asexual reproduction
Explain how a gene makes a protein Each gene codes for a particular sequence of amino acids, which makes a specific protein. DNA and the genome
Give three uses of the human genome Finding genes linked to disease, understanding and treating inherited disorders, and tracing past human migration. DNA and the genome
Explain how bases code for amino acids A sequence of three bases codes for one amino acid, so the order of bases controls the order of amino acids. DNA structure
Extract information from family trees Use the key and the phenotypes of parents and children to work out genotypes. Genetic inheritance
Predict disorder risks using Punnett squares For example, two carriers of cystic fibrosis have a 0.25 probability of an affected child. Inherited disorders
Explain the 0.5 chance of a boy All eggs carry an X chromosome and half of sperm carry X, half carry Y. Sex determination
Describe how mutations affect phenotype All variants arise from mutations: most have no effect on the phenotype, some influence it and very few determine it. Variation
Explain how a feature evolved Link variation to survival and reproduction, and the allele becoming more common over many generations. Evolution
Explain when populations become separate species When they can no longer interbreed to produce fertile offspring. Evolution
Explain the problems caused by inbreeding Breeds become prone to disease or inherited defects because variation is reduced. Selective breeding
Give benefits and concerns of GM crops Higher yields, against concerns about wild flowers, insects and effects on human health. Genetic engineering
Describe embryo transplants Split apart the cells of an early embryo before they become specialised and transplant the identical embryos into host mothers. Cloning
Explain why the theory was slowly accepted It challenged the idea that God made all living things, there was too little evidence, and inheritance was not understood. Theory of evolution
Explain the impact of their ideas Natural selection explains how the variety of life evolved and is the basis of modern biology. Speciation
Explain why Mendel's work was not recognised Nobody knew about chromosomes, genes or DNA, so his results could not be explained, and few scientists read his work. The understanding of genetics
Explain how fossils support evolution Fossils from rocks of different ages show how organisms have changed over millions of years. Evidence for evolution
Explain why the fossil record is incomplete Early soft-bodied organisms left few traces, and most traces were destroyed by geological activity. Fossils
Explain uncertainty about how life began So few traces of early life remain that scientists cannot be certain how life began. Fossils
Explain how a factor leads to extinction Link the factor to fewer individuals surviving and reproducing until none are left. Extinction
Explain how resistant strains develop A mutation makes some bacteria resistant; they survive the antibiotic and reproduce, so the resistant population rises. Resistant bacteria
Explain why the three-domain system was introduced Evidence from chemical analysis showed that some organisms are more different than their structure suggests. Classification of living organisms
Define a stable community All the species and environmental factors are in balance, so population sizes stay fairly constant. Communities
Explain how an abiotic change affects a species Link the factor to a life process, e.g. less light means less photosynthesis, so slower growth. Abiotic factors
Explain effects of new predators or pathogens Prey may not be adapted to escape a new predator and organisms may have no resistance to a new pathogen, so numbers can fall fast. Biotic factors
Explain adaptations to hot, cold and dry environments Link each feature to heat loss or water loss, e.g. spines instead of leaves reduce water loss. Adaptations
Estimate population size from quadrat data Mean number per m² × total area in m². Levels of organisation
Use a transect to investigate distribution Place quadrats at regular intervals along a line and measure the factor at each point. Levels of organisation
Explain the role of decomposers in cycling Microorganisms break down dead matter and waste, respire and release carbon dioxide, and return mineral ions to the soil. How materials are cycled
Explain how temperature, water and oxygen affect decay They affect the enzymes and respiration of decomposers, so how fast they break down the material. Decomposition
Calculate a rate of decay Divide the change (e.g. in mass or pH) by the time taken, or use 1 ÷ time for a timed end point. Decomposition
Classify changes as seasonal, geographic or human Seasonal changes follow the year, geographic changes vary from place to place, and some changes are caused by human activity. Impact of environmental change
Describe a change in distribution from data Say where the species is found now compared with before, using values from the map, table or graph. Impact of environmental change
Explain why high biodiversity makes ecosystems stable Species depend less on any one other species for food, shelter and maintaining the physical environment. Biodiversity
Explain the effects of acidic gases Gases such as sulfur dioxide dissolve in rain to make acid rain, which damages trees and makes lakes acidic. Waste management
Explain how destroying peat bogs affects biodiversity Less bog habitat means fewer of the plants, animals and microorganisms that live there can survive, so biodiversity falls. Land use
Explain how deforestation increases atmospheric carbon dioxide Burning releases carbon dioxide, microorganisms respire as the wood decays, and fewer trees remove carbon dioxide by photosynthesis. Deforestation
Explain why species distributions change As temperature or rainfall changes, species survive and breed in new areas and die out where conditions no longer suit them. Global warming
Describe positive and negative human interactions For example, replanting hedgerows is positive, while removing them to make bigger fields is negative. Maintaining biodiversity
Describe how decomposers feed They secrete enzymes onto dead matter, and the small soluble food molecules produced diffuse into them. Trophic levels
Construct an accurate pyramid of biomass Choose a scale, draw each bar with its width proportional to the biomass, and centre and label the bars. Pyramids of biomass
Calculate the efficiency of biomass transfer Efficiency = biomass at the higher level ÷ biomass at the lower level × 100. Transfer of biomass
Explain how environmental change affects food production If the rains fail or temperatures change, crops fail, which can lead to famine. Factors affecting food security
Explain how limiting movement increases efficiency Less energy is used for movement, so less energy is transferred to the environment and more of the food becomes biomass. Farming techniques
Explain how controlling temperature increases efficiency In warm surroundings less energy is transferred to the environment, so less food is respired to keep warm. Farming techniques
Calculate the percentage of food converted to biomass Gain in mass ÷ mass of food eaten × 100. Farming techniques
Explain how larger mesh nets help Young, small fish escape, so they can grow and reach breeding age. Sustainable fisheries
Explain how fishing quotas help Limiting the amount caught leaves enough adult fish to breed and replace those taken. Sustainable fisheries
Explain how GM crops can improve food supply They can give more food or better nutrition, e.g. golden rice makes a substance the body uses to make vitamin A. Role of biotechnology

Grade 7

Grade 7 checklist (PDF)

Compare sizes using orders of magnitude Put both sizes in the same unit, divide, and write the ratio as a power of ten: 1000 times bigger is 3 orders of magnitude. Eukaryotes and prokaryotes
Estimate sizes of sub-cellular structures Compare the structure with the whole cell, e.g. a nucleus a quarter of the width of a 20 µm cell is about 5 µm across. Animal and plant cells
Suggest adaptations of unfamiliar specialised cells Use the same ideas (surface area, mitochondria, shape, missing structures) for a cell you have not studied. Cell specialisation
Suggest how a cell changes as it differentiates It gains the sub-cellular structures its function needs, e.g. more mitochondria or ribosomes, and may change shape. Cell differentiation
Explain how electron microscopes improved understanding Their much higher resolution revealed small sub-cellular structures, such as ribosomes, and the detail inside mitochondria and chloroplasts. Microscopy
Calculate bacterial numbers after a given time Find the number of divisions, then multiply the starting number by 2 to the power of that number. Culturing microorganisms
Explain why the new cells are identical The DNA is copied exactly, and one copy of every chromosome goes to each new cell. Mitosis and the cell cycle
Interpret data on dividing cells e.g. use the percentage of cells in mitosis to estimate how long mitosis lasts. Mitosis and the cell cycle
Evaluate the use of stem cells Weigh possible treatments against risks such as viral infection, and against ethical or religious objections, then give a conclusion. Stem cells
Explain why large organisms need exchange surfaces Their small surface area to volume ratio and long diffusion distances mean diffusion through the body surface is too slow. Diffusion
Estimate cell concentration from a graph Read the concentration where the line of best fit crosses 0% change in mass. Osmosis
Explain how oxygen affects active transport Less oxygen means less aerobic respiration, so less energy is released and active transport slows. Active transport
Explain why large organisms need organ systems Large organisms have a small surface area to volume ratio, so they need specialised exchange organs and a transport system to supply every cell. Principles of organisation
Explain denaturing by high temperature or pH The active site changes shape, so the substrate no longer fits and the rate of reaction falls. The human digestive system
Calculate rates from the amylase practical Use the equation given, such as rate = 1000 ÷ time taken for the starch to be digested, and compare rates at each pH. The human digestive system
Explain how alveoli are adapted for gas exchange Millions of alveoli give a large surface area, with thin walls and a rich capillary network keeping a steep concentration gradient. The heart and blood vessels
Explain why the left ventricle wall is thicker It pumps blood at a higher pressure all round the body, while the right ventricle only pumps blood to the nearby lungs. The heart and blood vessels
Apply blood functions to unfamiliar situations For example, explain the effects of having too few platelets or too few red blood cells. Blood
Evaluate drugs, devices and transplants Weigh up how well and how quickly each works, risks, side effects, recovery, cost and the need for donors or lifelong drugs, then give a justified conclusion. Coronary heart disease
Evaluate how representative a sample is Large, random samples that include a range of people give data you can apply to the whole population. Health issues
Explain why correlation does not prove causation Another factor might explain the link, so a causal mechanism is needed before saying one factor causes a disease. Lifestyle and non-communicable diseases
Explain how several factors combine to cause disease Many diseases result from several risk factors interacting, e.g. smoking, poor diet and no exercise together raise heart disease risk. Lifestyle and non-communicable diseases
Link cancer to the cell cycle Changes to the genes that control cell division make cells divide by mitosis in an uncontrolled way. Cancer
Explain how leaf structure suits photosynthesis Link the thin, broad shape, transparent epidermis, chloroplast position, air spaces, stomata and veins to supplying light, carbon dioxide and water. Plant tissues
Explain how guard cells control water loss Guard cells become turgid to open the stomata and flaccid to close them, balancing gas exchange against water loss. Plant organ system
Explain how water moves through the plant Water evaporates from leaf cells and diffuses out through the stomata, and more water is drawn up the xylem to replace it. Plant organ system
Interpret data on the spread of a disease Describe trends in case numbers, calculate percentage changes and use the way the pathogen spreads to explain the pattern. Communicable (infectious) diseases
Explain how HIV leads to AIDS HIV attacks immune cells; when the immune system is badly damaged, the body cannot deal with other infections or cancers. Viral diseases
Explain why infected leaves must be destroyed Infected leaves, including fallen ones, still carry the fungus, which can spread to healthy leaves by water or wind. Fungal diseases
Explain why controlling mosquitoes controls malaria The protist's life cycle includes the mosquito, so it is normally passed between people only by mosquito bites. Protist diseases
Explain why antibodies are specific Each antibody fits only one antigen, so it binds to only one type of pathogen. Human defence systems
Explain effects of damage to a defence E.g. smoke stops cilia beating, so mucus and pathogens build up in the airways and infections are more likely. Human defence systems
Interpret graphs of antibody concentration After a second exposure, antibodies are made faster and in much larger amounts than after the first. Vaccination
Explain why antibiotic resistance is a concern Resistant strains are not killed by the antibiotic, so infections become hard to treat and the strains can spread. Antibiotics and painkillers
Explain why double blind trials are used Neither doctors nor patients know who has the drug, so their expectations cannot bias the results. Discovery and development of drugs
Explain why hybridoma cells are used They can divide, like the tumour cell, and make the antibody, like the lymphocyte. Producing monoclonal antibodies
Explain why monoclonal antibodies are identical They come from clones of a single hybridoma cell, so all the cells make the same antibody. Producing monoclonal antibodies
Explain how they are used to treat cancer The antibody binds only to cancer cells, delivering a radioactive substance, toxic drug or chemical that stops cell division. Uses of monoclonal antibodies
Explain their use in research with dyes An antibody attached to a fluorescent dye binds to a specific molecule, showing where it is in a cell or tissue. Uses of monoclonal antibodies
Explain how aphids damage plants Aphids feed on sap from the phloem, removing sugars that the plant needs for growth. Detection and identification of plant diseases
Explain an unfamiliar defence in context Decide what type of defence it is, then link it to fewer pathogens getting in or fewer animals eating the plant. Plant defence responses
Explain plant gas exchange in light and dark Plant cells respire all the time, so a plant gives out carbon dioxide in the dark but takes it in overall when photosynthesis is faster than respiration. Photosynthetic reaction
Find the limiting factor on multi-factor graphs (HT) Compare curves: if raising the second factor raises the curve, that factor was limiting the lower curve. Rate of photosynthesis
Use the inverse square law (HT) Light intensity is proportional to 1 ÷ distance², so doubling the distance gives a quarter of the light intensity. Rate of photosynthesis
Explain how nitrate shortage reduces growth Less nitrate means fewer amino acids and less protein, so fewer new cells are made and the plant grows less. Uses of glucose from photosynthesis
Explain why anaerobic respiration transfers less energy The oxidation of glucose is incomplete, so much of the energy stays in the lactic acid or ethanol. Aerobic and anaerobic respiration
Describe how lactic acid is removed (HT) Blood carries lactic acid from the muscles to the liver, where it is converted back into glucose. Response to exercise
Define oxygen debt (HT) The extra oxygen the body needs after exercise to react with the accumulated lactic acid and remove it from the cells. Response to exercise
Explain the importance of the small building blocks Sugars, amino acids, fatty acids and glycerol are what large molecules are built from and broken down into, so they can be reused. Metabolism
Analyse and evaluate reaction time data Calculate means, spot anomalies, judge conclusions and suggest control variables. Structure and function
Evaluate the benefits and risks of brain procedures Weigh possible benefits against risks such as damage to other areas, infection and uncertain results. The brain
Interpret ray diagrams of eye defects Show where light focuses and how a spectacle lens moves the focus onto the retina. The eye
Evaluate treatments for defects of vision Compare glasses, contact lenses, laser surgery and lens replacement for convenience, risk and cost. The eye
Explain how vasoconstriction and shivering warm you Less blood near the skin reduces energy transfer; shivering muscles respire, releasing energy. Control of body temperature
Apply temperature control to new contexts E.g. explain a runner's red skin and heavy sweating, or a swimmer's shivering. Control of body temperature
Describe how glucagon raises blood glucose Glucagon causes glycogen to be converted into glucose, which is released into the blood. Control of blood glucose concentration
Explain how urea is formed Excess amino acids are deaminated in the liver to form ammonia, which is converted to urea. Maintaining water and nitrogen balance
Explain how ADH controls water balance When the blood is too concentrated, the pituitary releases ADH, so the kidney tubules reabsorb more water. Maintaining water and nitrogen balance
Explain how the four hormones interact E.g. oestrogen inhibits FSH and stimulates LH; progesterone inhibits FSH and LH. Hormones in human reproduction
Give the disadvantages of fertility treatment It is emotionally and physically stressful, success rates are not high, and multiple births are risky. Hormones to treat infertility
Explain how thyroxine levels are controlled High thyroxine inhibits TSH release from the pituitary, so less thyroxine is released, and the reverse. Negative feedback
Explain gravitropism in shoots and roots Auxin collects on the lower side: it speeds up growth in shoots but slows it in roots. Control and coordination
State the roles of gibberellins and ethene (HT) Gibberellins initiate seed germination; ethene controls cell division and the ripening of fruit. Control and coordination
Explain how selective weed killers increase yield Auxin kills broad-leaved weeds but not narrow-leaved crops, so crops have less competition. Use of plant hormones
Explain the advantages of controlled ripening Unripe fruit is firm and less easily damaged in transport; ethene ripens it when needed. Use of plant hormones
Compare meiosis with mitosis Compare the number of divisions, the number of cells made, the chromosome number and whether the cells are identical. Meiosis
Explain why some organisms use both methods Asexual reproduction to increase numbers quickly in good conditions; sexual reproduction to give variation for when conditions change. Pros and cons of sexual and asexual reproduction
Discuss the importance of the human genome Explain how each use could benefit people, especially in medicine. DNA and the genome
Use complementary base pairing A always pairs with T, and C always pairs with G, on the opposite strand. DNA structure
Describe protein synthesis simply On ribosomes, carrier molecules bring amino acids in the order set by a template; the chain then folds into a unique shape. DNA structure
Construct a genetic cross to make predictions From the information given, work out the genotypes and gametes, draw the Punnett square and give probabilities. Genetic inheritance
Discuss the issues of embryo screening Give economic, social and ethical arguments for and against, using the information provided. Inherited disorders
Explain why the sperm determines sex Eggs always carry X, so the sex depends on whether the sperm carries an X or a Y. Sex determination
Use twin or clone data Identical twins and clones have the same genes, so differences between them are caused by the environment. Variation
Explain how a mutation can change a species A rare new phenotype that suits an environmental change can spread relatively quickly by natural selection. Variation
Compare selective breeding with natural selection In selective breeding humans choose which individuals breed; in natural selection the environment decides which survive to breed. Selective breeding
Evaluate the impact of selective breeding Weigh benefits such as more food against inbreeding and reduced variation. Selective breeding
Describe the main steps of genetic engineering Enzymes isolate the gene, it is inserted into a vector, and the vector puts the gene into the required cells. Genetic engineering
Describe adult cell cloning Remove an egg's nucleus, insert an adult body cell nucleus, give an electric shock, then put the embryo into a womb. Cloning
Describe Lamarck's theory Changes that happen to an organism during its lifetime can be inherited. Theory of evolution
Describe the steps that produce a new species Isolation, genetic variation, different conditions, natural selection, and finally no fertile offspring between the populations. Speciation
Explain Mendel's results using alleles Use dominant and recessive alleles to explain why a characteristic disappears and then reappears in a 3 : 1 ratio. The understanding of genetics
Explain how resistant bacteria show evolution Bacteria reproduce so quickly that natural selection of resistant strains can be seen over a short time. Evidence for evolution
Interpret an evolutionary tree Organisms sharing the most recent common ancestor are the most closely related. Fossils
Explain why variation reduces extinction risk Some individuals are more likely to have characteristics that let them survive the change. Extinction
Suggest causes from information given Use clues in a description or data to name the factor and explain its effect. Extinction
Explain why resistant strains spread People are not immune to the new strain and there is no effective treatment. Resistant bacteria
Explain why new antibiotics won't solve it Developing new antibiotics is costly and slow, so it is unlikely to keep up with new resistant strains. Resistant bacteria
Interpret evolutionary trees Organisms that share the most recent common ancestor are the most closely related. Classification of living organisms
Explain how new evidence changed classification Better microscopes revealed internal structures, and biochemistry revealed chemical differences, leading to new models. Classification of living organisms
Predict knock-on effects of changes in food webs Follow every arrow into and out of the changed species, give a reason for each effect and allow for other food sources. Communities
Explain knock-on effects through a community Show how a change that affects plants then affects the animals that eat them or shelter in them. Abiotic factors
Explain how competition can make a species decline If one species outcompetes another, the other's numbers can fall until too few are left to breed. Biotic factors
Explain adaptations using surface area to volume ratio A large, compact body has a small surface area to volume ratio, so it loses heat more slowly. Adaptations
Explain predator–prey cycles from a graph Prey rise first, giving predators more food; predators rise and eat more prey, so prey fall, then predators fall. Levels of organisation
Explain why the carbon and water cycles matter They return carbon dioxide for photosynthesis and supply fresh water on land, so organisms can grow and survive. How materials are cycled
Describe the milk decay required practical Time how long lipase takes to lower the pH of milk, shown by an indicator changing colour, at different temperatures. Decomposition
Explain why decay slows at high temperatures Above the optimum temperature the decomposers' enzymes are denatured, so decay slows down. Decomposition
Explain a change in a species' distribution Link the environmental change to survival and reproduction, e.g. warmer winters let a species survive further north. Impact of environmental change
Compare the stability of two ecosystems Use the numbers of species to explain which is more likely to be badly affected by a change. Biodiversity
Explain how fertiliser run-off kills aquatic life Algae grow, block light, plants die, decomposers respire and use up oxygen, so fish die. Waste management
Explain how using peat releases carbon dioxide Burning peat, or its decay by microorganisms once it is exposed to oxygen, releases carbon dioxide. Land use
Evaluate a decision about land use Weigh people's needs for homes, jobs and materials against the loss of habitats and biodiversity. Land use
Explain how cattle and rice fields add methane Cattle release methane from digestion, and microorganisms in flooded rice fields release methane. Deforestation
Evaluate clearing forest for crops or cattle Weigh food, income and renewable fuel against habitat loss and the carbon dioxide released. Deforestation
Explain how global warming reduces biodiversity Species that cannot adapt or move to suitable areas quickly enough may become extinct. Global warming
Explain conflicting pressures on maintaining biodiversity Conservation costs money and uses land that people also need for food, homes, jobs and income. Maintaining biodiversity
Identify trophic levels in a food web An animal can be at more than one trophic level if it eats organisms from different levels. Trophic levels
Read values from a pyramid using its scale Measure bars, convert with the scale and compare trophic levels by calculation. Pyramids of biomass
Explain why higher levels have fewer organisms Less biomass is available at each higher level, so fewer organisms can be supported. Transfer of biomass
Explain why food chains are short After a few transfers too little biomass is left to support another trophic level. Transfer of biomass
Explain why sustainable food production is needed Food must be produced without using up resources or damaging the environment, so that everyone can be fed in future. Factors affecting food security
Evaluate intensive farming, including ethical objections Weigh cheap, efficient food production against animal welfare, disease spread and antibiotic use. Farming techniques
Evaluate conservation methods using data Use stock or catch data to judge whether a method is working, and consider other factors. Sustainable fisheries
Explain advantages of culturing microorganisms for food They grow quickly, can be grown all year in any climate, and need little land. Role of biotechnology
Evaluate GM crops as a solution Weigh more or better food against concerns about wild flowers, insects and long-term effects on health. Role of biotechnology

Grade 8

Grade 8 checklist (PDF)

Give real sizes in standard form e.g. a real size of 0.000012 m is 1.2 × 10⁻⁵ m. Microscopy
Give population sizes in standard form e.g. 300 × 2⁶ = 19 200 = 1.92 × 10⁴ bacteria. Culturing microorganisms
Evaluate the benefits and drawbacks of vaccination Weigh the protection of individuals and populations against the fact that vaccines do not always work and can cause mild side effects. Vaccination
Explain how specificity lets antibodies target cells Each antibody binds only to one binding site on one antigen, so it attaches only to the chemical or cells carrying that antigen. Producing monoclonal antibodies
Evaluate the use of monoclonal antibodies Weigh their specificity and reduced harm to healthy cells against unexpected side effects, cost and the use of mice. Uses of monoclonal antibodies
Use symptoms to suggest a likely cause Link the evidence to a cause, e.g. purple or black spots suggest black spot, then say how to confirm it. Detection and identification of plant diseases
Evaluate greenhouse costs against extra yield (HT) Use data to decide whether the value of the extra crop from adding heat, light or carbon dioxide is more than the extra cost. Rate of photosynthesis
Explain fast breathing after exercise (HT) Breathing and heart rate stay high to supply the extra oxygen needed to repay the oxygen debt. Response to exercise
Explain insulin and glucagon in negative feedback The two hormones act in opposite directions, returning glucose to normal whenever it rises or falls. Control of blood glucose concentration
Interpret osmosis diagrams of animal cells Explain why animal cells swell and may burst, or shrink, in solutions of different concentration. Maintaining water and nitrogen balance
Explain why the cycle restarts without pregnancy Progesterone falls, the lining breaks down, and FSH is no longer inhibited, so another egg matures. Hormones in human reproduction
Evaluate IVF from different points of view Weigh benefits against risks for patients and doctors, including ethical issues such as unused embryos. Hormones to treat infertility
Interpret simple negative feedback diagrams Follow the arrows to predict and explain what happens when a hormone level rises or falls. Negative feedback
Analyse data on plant hormone use Calculate changes from trial data and weigh up benefits against costs. Use of plant hormones
Evaluate reproduction methods for an unfamiliar organism Weigh the speed and efficiency of asexual reproduction against the variation from sexual reproduction, using the information given. Pros and cons of sexual and asexual reproduction
Explain how a mutation can change a protein A changed base sequence can change the amino acid sequence, so the protein has a different shape and may not work. DNA structure
Deduce genotypes from family tree evidence For example, two unaffected parents with an affected child must both be heterozygous. Genetic inheritance
Evaluate embryo screening with a justified conclusion Weigh the benefits against the costs and concerns, and make a judgement supported by the information. Inherited disorders
Apply natural selection to unfamiliar examples Use the details given (predators, climate, food) in a logical chain of cause and effect. Evolution
Evaluate genetic engineering in agriculture and medicine Weigh the benefits against the risks and objections to reach a justified conclusion. Genetic engineering
Evaluate cloning in agriculture and medicine Weigh the benefits of many identical, useful organisms against reduced variation, possible health problems and ethical objections. Cloning
Explain why Lamarck's theory is rejected Changes during an organism's life do not change the genes passed on in its gametes, so in the vast majority of cases they cannot be inherited. Theory of evolution
Apply speciation to an unfamiliar example Use the barrier and the different conditions described in the question in each step. Speciation
Explain how scientific theories develop over time New evidence and methods from many scientists built up the gene theory step by step. The understanding of genetics
Explain unfamiliar adaptations from given information Use the description or data to link each feature to a specific survival problem in that habitat. Adaptations
Evaluate data on distribution changes Say what the data shows, whether it supports the claim, and what other factors or limitations there are. Impact of environmental change
Evaluate a conservation method using given data Weigh the evidence of success against costs and limitations, then reach a justified conclusion. Maintaining biodiversity
Explain why respiration causes large biomass losses Much of the absorbed glucose is respired to release energy for movement and keeping warm, so it never becomes new biomass. Transfer of biomass

Grade 9

Grade 9 checklist (PDF)

Explain effects of variants in non-coding DNA Non-coding DNA switches genes on and off, so variants there can change how genes are expressed. DNA structure

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