Cambridge O Level Biology (5090)
How your heart pumps 7,000 litres a day, why antibiotics stop working, how one cell becomes a whole person — biology is the science of you and everything alive around you.
Checked against the official Cambridge syllabus for exams in 2026, 2027 and 2028 · 18 October 2026
1.Quick facts
2.Why study Biology?
Cambridge's aims for this course, in plain words. By the end you should be able to:
- Understand how living things work, using real scientific ideas.
- Carry out experiments properly — handling variables and working safely.
- Use data and evidence to solve problems and see where methods have limits.
- Communicate clearly with the right biological terms.
- See how biology helps people and the environment — health, food, conservation.
- Enjoy science and feel ready for A Level and beyond.
Based on the 'Aims' in the official syllabus.
3.Why these topics?
Cells: the units of life
Every living thing is built from cells. You learn what's inside them, how substances move in and out by diffusion, osmosis and active transport, what we are made of chemically, and how enzymes speed up the reactions of life.
Plants feed the planet
Photosynthesis turns sunlight, water and carbon dioxide into food and oxygen. You learn how leaves are built for it, what minerals plants need, and how water travels from roots to leaves.
The human machine
Digestion, breathing, respiration, the heart and blood, and the kidneys — how your body gets energy, moves materials around and removes waste. You'll also see why smoking and poor diet harm the heart and lungs.
Disease and defence
How pathogens spread, how your immune system fights back, how vaccination protects whole communities, and why bacteria becoming resistant to antibiotics is one of medicine's biggest worries.
Control and coordination
Nerves, eyes, hormones and homeostasis keep your body temperature and blood sugar just right — including what goes wrong in diabetes. Plants respond too, growing towards light and against gravity.
Life goes on
Cell division, reproduction in plants and humans, DNA, inheritance and natural selection — then biotechnology and genetic modification, such as bacteria engineered to make human insulin.
Life on Earth
Food chains, the carbon and nitrogen cycles, ecosystems and biodiversity — and how deforestation and pollution affect them, and what conservation can do.
4.Topic map
- 1.1 Cell structure and function
- 1.2 Specialised cells, tissues and organs
- 2.1 Concept and use of a classification system
- 2.2 Features of organisms
- 3.1 Diffusion and osmosis
- 3.2 Active transport
- 4.1 Biological molecules
- 5.1 Enzyme action
- 5.2 Effects of temperature and pH
- 6.1 Photosynthesis
- 6.2 Leaf structure
- 6.3 Mineral nutrition
- 7.1 Uptake and transport of water and ions
- 7.2 Transpiration and translocation
- 8.1 Diet
- 8.2 Human digestive system
- 8.3 Absorption and assimilation
- 9.1 Human gas exchange
- 10.1 Respiration
- 10.2 Aerobic respiration
- 10.3 Anaerobic respiration
- 11.1 Circulatory system
- 11.2 Heart
- 11.3 Blood vessels
- 11.4 Blood
- 12.1 Disease
- 12.2 Antibiotics
- 12.3 Immunity
- 13.1 Excretion
- 13.2 Urinary system
- 14.1 Mammalian nervous system
- 14.2 Mammalian sense organs
- 14.3 Mammalian hormones
- 14.4 Homeostasis
- 14.5 Temperature control
- 14.6 Blood glucose control
- 15.1 Coordination and response in plants
- 16.1 Nuclear division
- 16.2 Asexual and sexual reproduction
- 16.3 Sexual reproduction in plants
- 16.4 Sexual reproduction in humans
- 17.1 Variation
- 17.2 DNA
- 17.3 Inheritance
- 17.4 Selection
- 18.1 Biotechnology
- 18.2 Genetic modification
- 19.1 Energy flow
- 19.2 Nutrient cycles
- 19.3 Ecosystems and biodiversity
- 19.4 Effects of humans on ecosystems
- 19.5 Conservation
5.O Level vs A Level
O Level shows you how living things work; A Level (9700) shows you the molecules and mechanisms behind it.
| Idea | At O Level (this course) | At AS & A Level |
|---|---|---|
| Cells | Cell parts and their jobs | Electron micrographs, organelles in detail, the cell cycle and mitosis |
| Molecules | Food tests; carbohydrates, fats, proteins | Structure of proteins, DNA, RNA and how protein synthesis works |
| Enzymes | Lock-and-key, temperature and pH | Enzyme kinetics, inhibitors, Vmax and Km |
| Energy | Photosynthesis and respiration equations | Krebs cycle, ATP, light-dependent and light-independent reactions |
| Health | Disease, antibiotics, vaccination | Infectious diseases (TB, malaria, HIV, cholera), antibodies and immunity |
| Genes | Inheritance, simple genetic diagrams, GM | Gene control, genetic technology, gene therapy, selection and evolution |
6.Exam pattern
Every paper is marked by Cambridge. Students who study online usually sit Paper 4, as it needs no lab — your exam centre confirms which practical paper it offers.
7.Types of questions
Examples are written by our teachers in Cambridge style to show the type of question — they are not copied from past papers.
8.Command words
| Word | Cambridge meaning | What to do |
|---|---|---|
| State | express in clear terms | Short and exact. |
| Define | give precise meaning | Learn key definitions word-for-word (e.g. osmosis). |
| Describe | state the points of a topic / give characteristics and main features | For graphs: the trend plus data with units. |
| Explain | set out purposes or reasons / make the relationships between things clear / say why and/or how and support with relevant evidence | Give the biological reason. |
| Compare | identify/comment on similarities and/or differences | Mention both things in every point. |
| Suggest | apply knowledge and understanding to situations where there are a range of valid responses to make proposals / put forward considerations | Use biology on an unfamiliar example. |
| Discuss | write about issue(s) or topic(s) in depth in a structured way | Give points for and against. |
| Evaluate | judge or calculate the quality, importance, amount, or value of something | Weigh up, then reach a judgement. |
Meanings are quoted from the 'Command words' table in the official syllabus.
9.What examiners reward
Biology has many terms to learn, but half the marks test using them — practise data questions as well as notes.
10.Grades
A*, A, B, C, D, E. 'Ungraded' means below E and is not shown on the certificate. Your certificate says GCE O LEVEL.
What it took in June 2026
| Grade | Marks out of 200 | Roughly |
|---|---|---|
| A* | 162–168 | about 81–84% |
| A | 135–141 | about 68–70% |
| B | 108–114 | about 54–57% |
| C | 82–88 | about 41–44% |
| D | 70–75 | about 35–38% |
| E | 58–62 | about 29–31% |
Minimum weighted marks out of 200 in June 2026 (the range covers the different paper variants). Boundaries move every series — aim well above them.
Medicine, dentistry and pharmacy routes usually expect an A or A* in Biology and Chemistry.
11.Practical skills
- Learn the food tests (starch, reducing sugars, protein, fats) and what a positive result looks like.
- Biological drawings: clear single lines, no shading, correct proportions, labels with ruled lines.
- Calculate magnification and convert between mm and µm.
- Plan fair tests: one independent variable, control the rest, repeat and calculate means.
- Describe results using numbers from the data, then explain them.
- No lab at home? Paper 4 (Alternative to Practical) is a written paper — videos of real experiments and real data build the same skills.
12.Books & resources
13.Common mistakes
- Saying enzymes are 'killed' — they are denatured.
- Mixing up mitosis and meiosis, or genes and alleles.
- Describing a graph without quoting any numbers or units.
- Using everyday words ('food goes to the blood') instead of terms like 'absorption' and 'assimilation'.
- Writing that plants respire only at night — they respire all the time.
Tips from our teachers.
14.Study plan
- Year 1, term 1Cells, classification, movement in and out of cells, biological molecules, enzymes (1–5).
- Year 1, term 2Plant nutrition and transport (6–7); human nutrition and gas exchange (8–9).
- Year 1, term 3Respiration, transport in humans, disease and immunity (10–12). First full past paper.
- Year 2, term 1Excretion, coordination and control in animals and plants (13–15).
- Year 2, term 2Reproduction, inheritance, biotechnology, ecology (16–19); practical-paper practice.
- Final monthsTimed past papers weekly; key-term flashcards; data-analysis practice.
Cambridge designs the course for about 130 guided learning hours. Add 2–3 hours a week of your own practice.
15.Where it can take you
Biology is the starting point for every health career.
Typical subject requirements — always check each university's own entry rules.
16.Biology in the real world
Ibn Sina (980–1037)
His Canon of Medicine was used as a medical textbook for centuries — he wrote about contagion and how diseases spread, ideas you meet in Topic 12.
Insulin from bacteria
Bacteria given the human insulin gene make the insulin many people with diabetes rely on — genetic modification in Topic 18.
Indus river dolphin
A rare, nearly blind dolphin found in Pakistan's Indus river. Protecting it is a real example of conservation and human effects on ecosystems (Topic 19).
Antibiotic resistance
Using antibiotics when they aren't needed helps resistant bacteria survive and spread — natural selection happening in hospitals today (Topics 12 and 17).
17.Frequently asked questions
Is O Level Biology a lot of memorising?
There are many terms, but half the marks test using them on data and new situations. Learn terms precisely, then practise applying them.
Which practical paper will I take?
Everyone takes Papers 1 and 2, plus either Paper 3 (lab) or Paper 4 (written Alternative to Practical). Online and private students usually take Paper 4 — confirm with your exam centre.
Is there maths in Biology?
Some — percentages, means, magnification, rates and reading graphs. A calculator is allowed in all parts of the exam.
Is O Level 5090 the same as IGCSE Biology 0610?
No. They are separate Cambridge syllabuses with different papers. This guide is for O Level 5090.
When can I sit the exam?
Every June and November.
18.Study it with us
Live online classes with experienced Cambridge teachers, weekly quizzes and assignments in your portal, past-paper practice, and progress reports your parents can see.
19.Official sources
- Official syllabus 5090 for exams in 2026, 2027 and 2028 (PDF)
- Grade threshold table, June 2026 (PDF)
- Endorsed resources for 5090
Cambridge says its syllabuses and specimen materials are the final authority on the content and structure of its exams. Always check you are using the syllabus for the year you sit the exam.