Cambridge O Level Combined Science Tutors Online

Cambridge O Level Combined Science is syllabus 5129. This page works from the syllabus for exams in 2026, 2027 and 2028. Exams are available in the November series, and in the June series in Brunei only.

This is the qualification for students who study biology, chemistry and physics together rather than as separate subjects. The content is numbered straight through from 1 to 27, in three sections: Biology covers topics 1 to 12, Chemistry covers 13 to 22, and Physics covers 23 to 27. Candidates study all three sections, so there is no choosing a favourite science.

All candidates take three components, and all candidates are eligible for grades A* to E. The grade range stops at E, and anything below it is ungraded. There is no Core and Extended tier, so every candidate sits the same three papers and is graded across the same range.

Paper 1 is Multiple Choice. It lasts 1 hour, carries 40 marks and is worth 30% of the qualification, and it consists of 40 four-option multiple-choice questions.

Paper 2 is Theory. It lasts 1 hour 45 minutes, carries 80 marks and is worth 50% of the qualification, and it consists of short-answer and structured questions.

Paper 3 is Experimental Skills and Investigations. It lasts 1 hour, carries 40 marks and is worth 20% of the qualification, all items are compulsory, and it tests the experimental skills in section 4 of the syllabus.

One detail about Paper 3 is worth knowing early, because students often assume otherwise. The syllabus states plainly that candidates will not be required to do experiments as part of this test. It is a written paper about experiments rather than a bench test, and notes for use in qualitative analysis are provided. So the marks come from being able to describe apparatus, plan an investigation, read data and evaluate a method on paper.

The experimental contexts that Paper 3 can draw on are published, and they are unusually concrete. In Biology they include simple quantitative experiments measuring the volume of solutions or liquids, mass, temperature, time and length, plus diffusion, osmosis, chemical tests on food, rates of enzyme-catalysed reactions, photosynthesis including rate and the effect of light intensity, heart rate and breathing rate, and calculating the magnification of biological specimens.

In Chemistry they include simple quantitative experiments measuring the volume of gas or solution, mass, temperature, time and length, plus rate of reaction, salt preparation, separation and purification techniques including filtration, crystallisation, simple distillation, fractional distillation and chromatography, identification of metal ions, non-metal ions and gases including by flame tests, pH and the use of litmus and universal indicator, test-tube reactions of dilute acids, displacement reactions of metals and halogens, and temperature changes during reactions.

In Physics they include measurement of physical quantities such as length, volume or force, measurement of small distances or short intervals of time, determining a derived quantity such as the extension per unit load for a spring, the value of a known resistance or the acceleration of an object, testing and identifying the relationship between two variables such as between the potential difference across a wire and its length, comparing measured quantities such as angles of reflection, comparing derived quantities such as density, cooling and heating including temperature measurement, experiments using springs and balances, timing motion or oscillations, electric circuits including connection and reconnection and measurement of current and potential difference, and optics experiments using optics pins, mirrors, prisms, and rectangular or semi-circular glass or Perspex blocks, including the use of transparent, translucent and opaque substances.

Every one of those lists ends the same way, and it is a fair warning: procedures using simple apparatus, in situations where the method may not be familiar to the candidate. So Paper 3 is not only about methods a class has already done. It can ask a student to make sense of an unfamiliar procedure, which is why the skills matter more than the specific experiments.

The subject content sections run as follows. Biology covers cells, enzymes, plant nutrition and transport, human nutrition, human gas exchange, respiration, transport in humans, drugs and their effects, coordination and control, development of organisms and continuity of life, biotechnology and genetic modification, and the relationships of organisms with one another and with the environment.

Chemistry covers states of matter, atoms, elements and compounds, stoichiometry, chemical energetics, chemical reactions, acids, bases and salts, the Periodic Table, metals, chemistry of the environment, and organic chemistry.

Physics covers motion, forces and energy, thermal physics, waves, electricity, and nuclear physics.

So this is a genuine three science course rather than a light version of one. A student has to hold biological processes, chemical reactions and physical laws at the same time, and the papers mix them rather than separating them by subject. That breadth is the defining challenge of the qualification.

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, covering planning experiments and investigations, making and recording observations, measurements and estimates, interpreting and evaluating experimental observations and data, and evaluating methods and suggesting possible improvements.

The overall weightings are AO1 at 50 per cent, AO2 at 30 per cent and AO3 at 20 per cent of the qualification. Within the examined papers the split is 63 per cent AO1 and 37 per cent AO2 for both Paper 1 and Paper 2, with nothing on AO3 in either. Paper 3 is 100 per cent AO3.

So the practical objective is tested in one place only, and it is a written paper. A student who can do the experiments but cannot write about them will still lose those marks, and a student who has never handled the apparatus can still score well if the thinking is sound.

The qualification is graded A*, A, B, C, D or E, with A* the highest and E the lowest. A candidate whose performance does not meet the standard required for grade E is ungraded, which is reported on the statement of results but not on the certificate.