How to Revise GCSE Science: A Topic-by-Topic Guide (Biology, Chemistry and Physics)

GCSE Science is one of the biggest content loads in the whole GCSE curriculum. Whether you're taking Combined Science (two GCSEs, six exam papers) or Triple Science (three separate GCSEs — Biology, Chemistry and Physics, six papers between them), the sheer volume of topics can make revision feel overwhelming. The good news is that Science rewards a structured, topic-by-topic approach more than almost any other subject, because each paper tests a defined, published list of content.

This guide breaks GCSE Science revision down by subject and topic, explains what examiners are actually looking for, and shows you how to build required practicals and command words into your plan — not just facts.

Combined Science vs Triple Science: what's different

Combined Science (sometimes called "Trilogy" or "Double Award") covers the same broad topic areas as Triple Science but in less depth, and results in two GCSE grades instead of three. Triple Science covers extra content in every subject — for example, extra physics topics like space, and additional chemistry around organic reactions.

Whichever you're taking, check your exam board's specification (AQA, Edexcel, OCR Gateway or OCR 21st Century) and use it as your revision checklist. Every topic on that list can be examined, and nothing outside it can — so it's the most efficient revision tool you own, and it's free.

Biology: revising by topic

Biology tends to reward students who can explain processes, not just recall facts. For each of the following areas, practise writing short explanations in full sentences, then check them against the mark scheme:

• Cell biology — structure of animal, plant and bacterial cells; microscopy calculations (magnification = image size ÷ actual size); mitosis and the cell cycle; stem cells.
• Organisation — enzymes and digestion; the heart, blood vessels and blood; cardiovascular disease and treatments; plant tissues and transport.
• Infection and response — pathogens and how they spread; the immune system; vaccination; antibiotics and drug development.
• Bioenergetics — photosynthesis and respiration, including the required practical on the effect of light intensity.
• Homeostasis and response — the nervous system, reflexes, the endocrine system and hormones, and control of blood glucose.
• Inheritance, variation and evolution — DNA structure, genetic crosses and Punnett squares, natural selection, and classification.
• Ecology — ecosystems, food webs, the carbon and water cycles, and biodiversity — a strong topic for six-mark evaluate/discuss questions.

Chemistry: revising by topic

Chemistry mixes recall with mathematical skills, so split your revision time between the two:

• Atomic structure and the periodic table — subatomic particles, electronic structure, and trends in groups 1, 7 and 0.
• Bonding, structure and properties — ionic, covalent and metallic bonding; the properties of different structures, including giant covalent structures and polymers.
• Quantitative chemistry — conservation of mass, moles, and calculating percentage yield and atom economy. This is where most marks are lost, so practise calculations weekly, not just before the exam.
• Chemical changes — reactivity series, extraction of metals, acids, bases and electrolysis.
• Energy changes — exothermic and endothermic reactions, and reaction profiles.
• Rate and extent of chemical change — factors affecting rate, and reversible reactions and equilibrium.
• Organic chemistry — crude oil, hydrocarbons, cracking, and (for Triple) alcohols, carboxylic acids and polymers.
• Chemical analysis and the atmosphere — tests for gases and ions, and the composition and evolution of the atmosphere, including climate change.

Physics: revising by topic

Physics has the highest proportion of equations of the three sciences. Make a single equation sheet, but don't just memorise it — practise rearranging and substituting into each formula until it's automatic:

• Energy — stores and transfers, efficiency calculations, and specific heat capacity.
• Electricity — circuits, current, potential difference and resistance; the required practicals on I-V characteristics and resistance are common exam sources.
• Particle model of matter — density, changes of state, and particle motion in gases.
• Atomic structure — radioactive decay, half-life calculations, and uses and dangers of radiation.
• Forces — Newton's laws, moments, momentum, and required practicals on acceleration and force.
• Waves — wave properties and calculations, the electromagnetic spectrum, and uses of different wave types.
• Magnetism and electromagnetism — magnetic fields, the motor effect, and electromagnetic induction.
• Space physics (Triple Science only) — the life cycle of stars, orbital motion, and red-shift.

Don't skip the required practicals

Every exam board's specification includes a set list of required practicals for each science, and exam boards write a significant number of marks each year around them — not asking you to repeat the method, but to analyse results, identify variables, spot sources of error, or suggest improvements. If you haven't actually done a practical in school, look up a summary of its method, apparatus and typical results, and practise the kind of "evaluate this experiment" question that comes with it.

Command words and the six-mark questions

Science exams use precise command words — state, describe, explain, evaluate, calculate — and each expects a different style of answer. "Explain" always wants a reason or mechanism (using words like "because" or "so that"), while "describe" wants what happens without saying why. The longer six-mark questions, often asking you to evaluate or compare, are marked using levels of response: a good structure (a clear point, then supporting detail, then a conclusion) will usually outscore a longer but disorganised answer covering the same content.

Building a science revision plan

Combine three approaches rather than relying on one: build flashcards or a knowledge organiser for core facts and use active recall to test yourself against it; space your revision of each topic out over several weeks instead of massing it into one session; and use past papers, marked against the official mark scheme, to convert knowledge into exam marks. Past papers are especially valuable in Science because so many marks depend on applying a formula or explaining a process in the exact way examiners expect.

FAQ

How many GCSE Science exams will I sit?
Combined Science students sit six papers (two Biology, two Chemistry, two Physics) resulting in two grades. Triple Science students also sit six papers, but each is a separate Biology, Chemistry or Physics exam, resulting in three grades.

Is a calculator allowed in GCSE Science?
Yes, for all three sciences, across all major exam boards — so practise using your own calculator during revision, not just on exam day.

Which topic should I revise first?
Start with whichever topic you find hardest while you still have time to come back to it, then use spaced repetition to keep revisiting topics you've already covered so they don't fade before the exam.

Do required practicals come up every year?
Not every practical appears every year, but across the full set of papers, most exam boards draw on a good proportion of them, so it's not safe to skip any.

Feeling behind on GCSE Science with exams approaching? RevisionLab builds personalised revision resources and study plans for GCSE and A-Level students, so you always know exactly what to revise next.