GCSE Biology Exam Study Guide (2027)
Everything the GCSE Biology (9-1) Exam tests, topic by topic: what each section covers, the facts that come up most, and how to study it. Pair it with the free 15-question practice test.
The exam at a glance
| Questions | AQA: 2 written papers, 100 marks each (200 marks in total). Edexcel 1BI0 is also 2 × 100 marks; OCR Gateway J247 is 2 × 90 marks |
|---|---|
| Time | 3 hours 30 minutes in total (2 × 1 hour 45 minutes); the same for AQA, Edexcel and OCR |
| Grades and pass mark | Grade 4 is a standard pass and grade 5 a strong pass. Boundaries are set after every exam series, so aim for 70% in practice |
| Format | Written exam, calculator allowed on both papers. Foundation tier (grades 1 to 5) or Higher tier (grades 4 to 9), and both papers must be taken at the same tier |
| Exam boards | AQA, Pearson Edexcel and OCR |
| Test provider | At your school or college, or as a private candidate at an exam centre that accepts them |
Mind map: the whole exam on one screen
Read the complete GCSE Biology study notes for “Cell Biology”
Our first full set of comprehensive notes, about 18 minutes of reading: Animal, plant and bacterial cells · Size, units and magnification · Specialised cells and differentiation · Chromosomes, the cell cycle and mitosis · Stem cells · Culturing microorganisms (separate biology) · Diffusion, osmosis and active transport, a worked exam example, the traps examiners use and a one-minute recap. Create a free account to read it and see how premium notes work before you decide.
1. Cell Biology
Paper 1. Eukaryotic and prokaryotic cells, microscopy and magnification, specialised cells, culturing microorganisms, the cell cycle and mitosis, stem cells, and transport by diffusion, osmosis and active transport.
Key facts
- Animal cells have a nucleus, cytoplasm, cell membrane, mitochondria and ribosomes. Plant cells also have a cellulose cell wall, chloroplasts and usually a permanent vacuole filled with cell sap.
- Prokaryotic cells (bacteria) are much smaller than eukaryotic cells and have no nucleus: their genetic material is a single loop of DNA in the cytoplasm, and they may also have small rings of DNA called plasmids.
- magnification = size of image ÷ size of real object. Convert to the same unit first: 1 mm = 1000 µm and 1 µm = 1000 nm. Electron microscopes have much higher magnification and resolving power than light microscopes, so they show sub-cellular structures such as ribosomes.
- Cells specialise by differentiation: sperm cells (tail, many mitochondria), nerve cells (long, with branched endings), muscle cells (many mitochondria), root hair cells (large surface area), xylem (hollow tubes strengthened by lignin) and phloem (sieve plates and companion cells). Most animal cells differentiate early; many plant cells can differentiate throughout life.
- Bacteria divide by binary fission, as often as every 20 minutes. Aseptic technique (sterilised Petri dishes and loops, lid taped but not sealed, incubation at 25 °C in schools) stops contamination and the growth of harmful pathogens. Number of bacteria = 2 to the power of the number of divisions.
- In the cell cycle, the cell grows, copies its DNA and sub-cellular structures (mitochondria, ribosomes), then in mitosis one set of chromosomes is pulled to each end; finally the cytoplasm and cell membrane divide to form two identical cells. Mitosis is used for growth and repair.
- Stem cells are undifferentiated. Embryonic stem cells can become most cell types; adult bone marrow stem cells form many types, including blood cells; meristems in plant root and shoot tips can form any plant cell throughout life. In therapeutic cloning the embryo has the patient's own genes, so the cells are not rejected.
- Diffusion is the net movement of particles from a higher to a lower concentration; it is faster with a steeper concentration gradient, a higher temperature and a larger surface area. Osmosis is the diffusion of water from a dilute to a more concentrated solution through a partially permeable membrane. Active transport moves substances against a concentration gradient using energy from respiration.
Flashcards
Exam tip: In the osmosis practical, calculate the percentage change in mass, not just the change, because the cylinders start at different masses. In written answers, say water moves 'from a dilute solution to a more concentrated solution'.
2. Organisation
Paper 1. Levels of organisation, the digestive system and enzymes, food tests, the heart, blood vessels and blood, coronary heart disease and other non-communicable diseases, and plant tissues, transpiration and translocation.
Key facts
- Cells form tissues, tissues form organs, organs form organ systems. The digestive system breaks large insoluble molecules into small soluble ones that can be absorbed into the bloodstream through the villi of the small intestine.
- Enzymes are biological catalysts made of protein. The substrate fits the active site (lock and key model). High temperature or extreme pH denatures the enzyme by changing the shape of its active site. Rate = 1 ÷ time.
- Carbohydrases such as amylase break carbohydrates into simple sugars; proteases break proteins into amino acids; lipases break lipids into fatty acids and glycerol. Bile is made in the liver, stored in the gall bladder, neutralises stomach acid and emulsifies fats to increase their surface area.
- Food tests: Benedict's reagent heated in a water bath turns from blue to green, yellow or brick red with reducing sugars; iodine turns from orange-brown to blue-black with starch; Biuret reagent turns from blue to purple with protein; ethanol gives a cloudy white emulsion with lipids.
- The heart is a double pump: the right side pumps deoxygenated blood to the lungs and the left side pumps oxygenated blood to the body. A group of cells in the right atrium acts as a natural pacemaker; artificial pacemakers correct irregular heart rhythms.
- Arteries have thick muscular and elastic walls for high pressure; veins have thinner walls, a large lumen and valves; capillaries have walls one cell thick for exchange. Blood is plasma carrying red blood cells (haemoglobin, no nucleus), white blood cells and platelets.
- Coronary heart disease: fatty material builds up in the coronary arteries, so less oxygen reaches the heart muscle. Treatments include stents, statins (reduce blood cholesterol), replacement valves and transplants. Risk factors for non-communicable diseases include diet, smoking, alcohol and lack of exercise; cancer results from uncontrolled cell division.
- In plants, xylem carries water and mineral ions from the roots to the leaves (the transpiration stream) and phloem carries dissolved sugars in both directions (translocation). Transpiration rate increases with temperature, light intensity and air movement and decreases with humidity. Guard cells open and close the stomata.
Flashcards
Exam tip: When explaining denaturation, mention that the active site changes shape so the substrate no longer fits. Never say the enzyme is 'killed'.
3. Infection and Response
Paper 1. Communicable diseases caused by viruses, bacteria, fungi and protists, human defence systems, vaccination, antibiotics and painkillers, drug discovery and trials, monoclonal antibodies and plant disease.
Key facts
- Pathogens are microorganisms that cause infectious disease. Viruses live and reproduce inside cells, damaging them; bacteria may produce toxins that damage tissues. Pathogens spread by air (droplets), direct contact and water.
- Examples to learn: measles, HIV and tobacco mosaic virus (viruses); salmonella food poisoning and gonorrhoea (bacteria); rose black spot (fungus); malaria (a protist spread by mosquitoes).
- Non-specific defences: skin, nose hairs and mucus, cilia and mucus in the trachea and bronchi, and stomach acid. White blood cells defend by phagocytosis, producing antibodies and producing antitoxins.
- Vaccination introduces small quantities of dead or inactive pathogen. White blood cells make antibodies, so if the live pathogen enters later the response is rapid. Vaccinating most of a population reduces the spread of a disease.
- Antibiotics such as penicillin kill bacteria inside the body but not viruses; painkillers only treat symptoms. Overuse of antibiotics has led to resistant strains such as MRSA. Traditional drugs came from plants (digitalis from foxgloves, aspirin from willow).
- New drugs go through preclinical testing (cells, tissues and live animals) for toxicity, efficacy and dose, then clinical trials: very low doses on healthy volunteers first, then patients. In double-blind trials neither doctors nor patients know who has the drug or the placebo.
- Monoclonal antibodies are made by fusing mouse lymphocytes with a tumour cell to make a hybridoma cell, which divides and makes one type of antibody. Uses include pregnancy tests, measuring hormone levels, locating clots or cancer cells, and carrying drugs to cancer cells. They have caused more side effects than expected.
- Plant disease signs: stunted growth, spots on leaves, decay, growths, malformed stems or leaves, discolouration and pests. Nitrate deficiency causes stunted growth (less protein); magnesium deficiency causes chlorosis (less chlorophyll). Plant defences include cellulose cell walls, a waxy cuticle, bark, poisons, thorns and drooping leaves.
Flashcards
Exam tip: Learn one named example of each pathogen type with its symptoms, spread and control. Extended questions often ask you to compare two diseases.
Test yourself on these topics
Take the free 15-question GCSE Biology test, then save your results to unlock your Readiness Score and the mistakes bank.
4. Bioenergetics
Paper 1. Photosynthesis and limiting factors, how plants use glucose, aerobic and anaerobic respiration, the body's response to exercise, and metabolism.
Key facts
- Photosynthesis: carbon dioxide + water → glucose + oxygen (6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂). It is endothermic: energy is transferred from the environment to the chloroplasts by light.
- Limiting factors are temperature, light intensity, carbon dioxide concentration and the amount of chlorophyll. On a graph, the factor on the x-axis is limiting where the line rises; where the line levels off, another factor is limiting.
Flashcards
Exam tip: On limiting-factor graphs, name the limiting factor for each part of the curve and give a reason. 'Light is the limiting factor because increasing it increases the rate' is the shape of a full-mark answer.
5. Homeostasis and Response
Paper 2. Homeostasis, the nervous system and reflexes, the brain and the eye, body temperature, hormones and blood glucose, the kidneys, reproductive hormones and contraception, and plant hormones.
Key facts
- Homeostasis keeps internal conditions such as blood glucose, body temperature and water levels at optimum levels. Control systems have receptors, coordination centres (brain, spinal cord, pancreas) and effectors (muscles or glands).
- Reflex arc: stimulus → receptor → sensory neurone → relay neurone in the spinal cord → motor neurone → effector → response. Reflexes are automatic and rapid; chemicals carry the signal across synapses.
Flashcards
Exam tip: Negative feedback answers need the full loop: the change, what detects it, the hormone or nerve response, the effect, and the return to normal.
6. Inheritance, Variation and Evolution
Paper 2. Sexual and asexual reproduction, meiosis, DNA and protein synthesis, genetic crosses and inherited disorders, variation and evolution, selective breeding, genetic engineering, cloning and classification.
Key facts
- Sexual reproduction joins male and female gametes made by meiosis, producing variation. Asexual reproduction involves one parent and mitosis, producing genetically identical clones. Some organisms do both, such as malaria parasites, many fungi, strawberries and daffodils.
- Meiosis: the chromosomes are copied, then the cell divides twice to form four gametes, each with a single set of chromosomes and all genetically different. Fertilisation restores the full number: 46 chromosomes (23 pairs) in humans.
Flashcards
Exam tip: In genetic crosses show the parental genotypes, the gametes and a Punnett square, then give exactly what is asked: a ratio, a percentage or a probability.
7. Ecology
Paper 2. Communities and interdependence, abiotic and biotic factors, adaptations, food chains and sampling, the carbon and water cycles, decomposition, biodiversity and human impact, trophic levels and food production.
Key facts
- An ecosystem is the interaction of a community of living organisms with the non-living parts of their environment. Interdependence means species depend on each other for food, shelter, pollination and seed dispersal. In a stable community, population sizes stay fairly constant.
- Abiotic factors: light intensity, temperature, moisture, soil pH and mineral content, wind, carbon dioxide for plants and oxygen for aquatic animals. Biotic factors: food availability, new predators, new pathogens and competition. Adaptations are structural, behavioural or functional; extremophiles live in extreme conditions.
Flashcards
Exam tip: In quadrat calculations, write each step: total area sampled, number per m², then multiply by the area of the field. Forgetting the quadrat area is the most common error.
How to pass
- 100 marks in 105 minutes is about 1 minute per mark. A 6-mark extended answer deserves about 6 minutes: plan three linked points with a reason for each.
- Required practicals are examined in the written papers. Know the method, the variables and the safety point for all 10 AQA biology practicals, especially osmosis, enzymes, photosynthesis and the food tests.
- Command words matter: 'describe' means say what happens, 'explain' means say why, and 'evaluate' needs a judgement backed by evidence from the question.
- In calculations show every step and give units. Magnification, percentage change in mass, rate (1 ÷ time) and quadrat estimates come up in almost every series.
- Never say enzymes are 'killed' or that bacteria 'become immune'. Use 'denatured' and 'resistant'; vague words lose marks even when the idea is right.
Frequently asked questions
How long should I study for the GCSE Biology exam?
Most students do best starting 10 to 12 weeks before the first paper, with 30 to 45 minutes a day per subject. You're ready once your Readiness Score has stayed at 80 or higher for about a week.
Can I take the GCSE Biology exam online?
No. GCSE Biology is a written exam sat in person at your school, college or an approved exam centre. Format: written exam, calculator allowed on both papers. Foundation tier (grades 1 to 5) or Higher tier (grades 4 to 9), and both papers must be taken at the same tier. Check your exam board's timetable for dates.
What score do I need to pass the GCSE Biology exam?
Grade 4 is a standard pass and grade 5 a strong pass. Boundaries are set after every exam series, so aim for 70% in practice. The exam has aqa: 2 written papers, 100 marks each (200 marks in total). edexcel 1bi0 is also 2 × 100 marks; ocr gateway j247 is 2 × 90 marks and a time limit of 3 hours 30 minutes in total (2 × 1 hour 45 minutes); the same for aqa, edexcel and ocr.
What are the most tested topics?
The outline covers cell biology, organisation, infection and response, bioenergetics, homeostasis and response, inheritance, variation and evolution, ecology. Use the free practice test to see which ones you need most.
The premium GCSE Biology study path
Premium GCSE Biology prep is studied one topic at a time. Each step starts with that topic's key notes and flashcard deck, then its own question sets of 25, so you master one topic before you move to the next. When every topic is strong, the 6 full mock exams show you're ready.
Your step-by-step study path
- 1Cell Biology9 key notes, 115 flashcards, then 450 practice questions in 18 sets of 25Notes free with an account
- 2Organisation9 key notes, 115 flashcards, then 425 practice questions in 17 sets of 25Premium
- 3Infection and Response9 key notes, 115 flashcards, then 425 practice questions in 17 sets of 25Premium
- 4Bioenergetics9 key notes, 115 flashcards, then 425 practice questions in 17 sets of 25Premium
- 5Homeostasis and Response8 key notes, 115 flashcards, then 425 practice questions in 17 sets of 25Premium
- 6Inheritance, Variation and Evolution8 key notes, 115 flashcards, then 425 practice questions in 17 sets of 25Premium
- 7Ecology8 key notes, 110 flashcards, then 425 practice questions in 17 sets of 25Premium
- Final step: 6 full mock exams50 questions each, timed like exam day. Hit your target on them before your first paper.Premium
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Summarised from the exam boards' published specifications and the rules cited, checked November 2026. Confirm current requirements with AQA, Pearson Edexcel and OCR.