Biology has more content to learn than most subjects, so it's tempting to revise by reading and highlighting. The students who score highest do something different: they practise answering questions in the precise language examiners reward. These tips are for Cambridge IGCSE Biology (0610) and O Level Biology (5090).
1. Learn definitions word for word
Terms such as diffusion, osmosis, active transport, enzyme, homeostasis, gene and allele are marked on key phrases. For example, osmosis is the net movement of water molecules from a region of higher water potential to a region of lower water potential through a partially permeable membrane. Leave out "partially permeable membrane" and the mark can go. Build a definitions list from mark schemes and test yourself every few days.
2. Understand processes as a sequence
Digestion, blood clotting, the reflex arc, transpiration and the menstrual cycle are all sequences of steps. Write each one as a numbered chain and practise explaining it out loud. When a question asks you to explain, each step in the chain is usually a mark.
3. Know the core equations and conditions
| Process | Word equation | Key points |
|---|---|---|
| Photosynthesis | carbon dioxide + water → glucose + oxygen | Needs light and chlorophyll; limiting factors are light, carbon dioxide and temperature |
| Aerobic respiration | glucose + oxygen → carbon dioxide + water | Releases energy in all living cells |
| Anaerobic respiration (muscles) | glucose → lactic acid | Releases much less energy; leads to an oxygen debt |
| Anaerobic respiration (yeast) | glucose → ethanol + carbon dioxide | Used in bread-making and brewing |
Extended and O Level students should also learn the balanced symbol equations, for example 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ for photosynthesis.
4. Explain enzymes properly
Enzymes are biological catalysts, and questions about them come up across many topics. Use the lock-and-key idea: the substrate fits the active site, which has a complementary shape. At high temperatures or extreme pH, the active site changes shape, the enzyme is denatured and the substrate no longer fits. Say "denatured", never "killed".
5. Practise data and graph questions
- When describing a trend, say what happens and quote figures from the graph with units.
- Mention any change in trend, such as a peak or a levelling off, and where it happens.
- When asked to explain, give the biological reason, not a repeat of the description.
- Show working for percentage change and magnification (magnification = image size ÷ actual size), and convert units first.
6. Draw biological diagrams the examiner's way
Use a sharp pencil, clear continuous lines, no shading, and label lines drawn with a ruler that touch the structure. Make the drawing large enough to fill most of the space given. These are easy marks to lose through rushing.
7. Train for the practical paper
Whether you take a practical test or the Alternative to Practical paper, the skills are predictable: food tests (Benedict's, iodine, biuret, ethanol emulsion), identifying independent, dependent and controlled variables, drawing results tables with units, plotting graphs, and suggesting improvements such as repeats or controlling temperature. Make a one-page summary of the food tests with reagents, method and colour changes. When planning an investigation, state what you will change, what you will measure, what you will keep the same, and how you will make the results reliable.
8. Revise by topic, then by paper
Answer topical past paper questions straight after revising each topic, and move to full timed papers in the last three months. Our guide on how to use past papers explains the method, and our Chemistry revision tips are useful if you're revising both sciences together.
Common mistakes to avoid
- Saying plants respire only at night (they respire all the time).
- Writing "energy is produced" instead of "energy is released" in respiration.
- Confusing genes and alleles, or genotype and phenotype, in genetics questions.
- Describing a graph without quoting any values.
Need help with Biology?
Our online Biology tutors teach IGCSE 0610 (Core and Extended), O Level 5090 and A Level Biology, one-to-one from $12/hour for IGCSE and O Level, or in small groups from $25/month. See our O Level course for subjects and class options.
Frequently asked questions
01What is the hardest topic in IGCSE Biology?
Many students find inheritance and genetic diagrams, transport in plants and animals, and the nervous and hormonal systems hardest. These topics reward understanding the sequence of steps rather than memorising isolated facts.
02How do I get an A* in O Level Biology?
Learn definitions and processes in mark scheme wording, practise data and graph questions regularly, drill the practical skills, and sit full timed papers in the final three months, fixing every lost mark.
03Is Biology mostly memorisation?
There is a lot to learn, but the higher-mark questions ask you to explain, apply and suggest. Students who understand why a process happens score far better on unfamiliar questions than those who only memorise notes.
