Cambridge O Level Biology Tutors Online

Cambridge O Level Biology is syllabus 5090. This page works from the syllabus for exams in 2026, 2027 and 2028. Exams are available in the June and November series, and the syllabus notes that it is not available in all administrative zones.

All candidates take three components, and all candidates are eligible for grades A* to E. There is no Core and Extended tier.

Paper 1 is Multiple Choice. It lasts 1 hour, carries 40 marks and is worth 30%. It contains 40 four-option multiple-choice questions, all compulsory, and tests assessment objectives AO1 and AO2.

Paper 2 is Theory. It lasts 1 hour 45 minutes, carries 80 marks and is worth 50%. It contains compulsory short-answer and structured questions, and it also tests AO1 and AO2 only.

The third component is a practical assessment, and candidates take one paper from a choice of two. Paper 3 is the Practical Test, lasting 1 hour 30 minutes and carrying 40 marks. Paper 4 is the Alternative to Practical, lasting 1 hour and carrying 40 marks. Both are worth 20% and both are externally assessed.

The difference between the two is physical rather than academic. Candidates taking the Practical Test are required to do experiments in a laboratory as part of the test. Candidates taking the Alternative to Practical are not required to do experiments. Everything else is the same: both require the same experimental skills to be developed and learned, both require an understanding of the same experimental contexts, and both test the same assessment objective, AO3.

That matters because families sometimes treat Paper 4 as an easier route. It is not easier in terms of knowledge. It is the same AO3 skills assessed through written questions about experimental work rather than through doing the work by hand, so the same preparation is needed either way.

The split of assessment objectives is one of the cleanest in any O Level science. Papers 1 and 2 test AO1 and AO2 and nothing else. The practical paper tests AO3 and nothing else. No paper mixes the three.

The content is organised into nineteen topics. They are cells; classification; movement into and out of cells; biological molecules; enzymes; plant nutrition; transport in flowering plants; human nutrition; human gas exchange; respiration; transport in humans; disease and immunity; excretion; coordination and control; coordination and response in plants; development of organisms and continuity of life; inheritance; biotechnology and genetic modification; and relationships of organisms with one another and with the environment.

The syllabus is unusually specific about what each topic requires. Topic 1 on cells, for example, does not simply say that cells should be studied. It requires candidates to examine animal and plant cells under the microscope using an appropriate temporary staining technique such as methylene blue or iodine solution, to draw diagrams of what they observe, to identify the ribosomes, mitochondria, nucleus, cytoplasm and cell membrane in an animal cell, to identify the ribosomes, mitochondria, chloroplasts, nucleus, sap vacuole, cytoplasm, cell membrane and cellulose cell wall in a plant cell, and to describe the structure of a bacterial cell limited to ribosomes, circular DNA and plasmids, cytoplasm, cell membrane and cell wall.

That level of detail runs through all nineteen topics. Each one is broken into named sub-topics with numbered learning outcomes, so a candidate can see exactly what has to be learned rather than working from a general topic heading.

The assessment objectives are three. AO1 is knowledge with understanding, covering scientific phenomena, facts, laws, definitions, concepts and theories; scientific vocabulary, terminology and conventions including symbols, quantities and units; scientific instruments and apparatus including techniques of operation and aspects of safety; and scientific and technological applications with their social, economic and environmental implications. AO2 is handling information and problem solving. AO3 is experimental skills and investigations.

Overall, AO1 is worth 50 per cent, AO2 is worth 30 per cent and AO3 is worth 20 per cent of the qualification.

Per component, Paper 1 is 63 per cent AO1 and 37 per cent AO2. Paper 2 is 63 per cent AO1 and 37 per cent AO2, exactly the same split. Papers 3 and 4 are 100 per cent AO3.

So half the qualification is knowledge with understanding, and the practical paper is the only place where experimental skill is tested. A candidate who memorises content but has never handled apparatus, read a thermometer carefully or described a food test will lose the whole of that 20 per cent.

The syllabus publishes the experimental contexts that the practical paper can draw on, which is the most useful revision list in the document. Candidates are expected to be familiar with and may be asked questions using simple quantitative experiments including measurement of volumes of gases or solutions and liquids, masses, temperatures, times and lengths; diffusion; osmosis; food tests; rates of enzyme-catalysed reactions; pH and the use of hydrogencarbonate indicator, litmus and universal indicator; photosynthesis including rate and limiting factors; the effect of mineral ions on plant growth; transpiration; heart rate and breathing rate; respiration; tropic responses; nervous responses; observation and dissection of seeds and flowers; germination; continuous and discontinuous variation; sampling techniques; use of a microscope to examine biological specimens; calculating the magnification of biological specimens; and procedures using simple apparatus in situations where the method may not be familiar to the candidate.

Alongside that, candidates may be required to identify apparatus from diagrams or descriptions, draw, complete or label diagrams of apparatus and biological specimens, use or explain the use of common techniques, apparatus and materials, select the most appropriate apparatus or method for a task and justify the choice, describe food tests, describe tests to determine the pH of solutions and substances, describe and explain hazards and identify safety precautions, and describe and explain techniques used to ensure the accuracy of observations and data.

The syllabus also states the broader purpose of practical work: it helps students use equipment and materials accurately and safely, develop observational and problem-solving skills, deepen their understanding of the syllabus topics and the scientific approach, appreciate how scientific theories are developed and tested, transfer experimental skills to unfamiliar contexts, develop positive scientific attitudes such as objectivity, integrity, cooperation, enquiry and inventiveness, and develop an interest and enjoyment in science.

The qualification is graded A*, A, B, C, D or E.