IGCSE Biology: Organisation of the Organism (Cambridge 0610)

This guide covers Topic 2 Organisation of the organism, for Cambridge IGCSE Biology 0610, 2026–2028 series. Cambridge IGCSE Biology is tiered — Core content is examined at grades C–G, and Extended candidates (Core + Supplement) are assessed for grades A*–G — and this guide marks which outcomes belong to each tier.

Where this fits in 0610

Organisation of the organism is the second of twenty-one topics in 0610, sitting directly after Characteristics and classification of living organisms and before Movement into and out of cells. It moves the syllabus from the whole-organism question of “what counts as living?” down to the structural question of “what is a living thing actually built from?” — the cell comparisons and specialised-cell examples introduced here are assumed knowledge for almost everything that follows: the transport topics later in the syllabus depend on knowing what a cell membrane and cytoplasm are, and topics on nutrition, respiration and coordination all describe specialised cells doing a job, which only makes sense once the idea of cell specialisation from this topic is secure. Like the diffusion sub-topic, this topic carries no Supplement content of its own within 2.1 — the cell-structure outcomes are examined identically for Core and Extended candidates, with the tier distinction only appearing in the unit-conversion skill in 2.2.

Syllabus coverage

CAMBRIDGE IGCSE BIOLOGY 0610 — TOPIC 2 ORGANISATION OF THE ORGANISM

• 2.1 Cell structure (Core) — describing and comparing the structure of a plant cell with an animal cell, limited to: cell wall, cell membrane, nucleus, cytoplasm, chloroplasts, ribosomes, mitochondria and vacuoles; describing the structure of a bacterial cell, limited to: cell wall, cell membrane, cytoplasm, ribosomes, circular DNA and plasmids; identifying these cell structures in diagrams and images of plant, animal and bacterial cells; describing the functions of each structure in plant, animal and bacterial cells; stating that new cells are produced by division of existing cells; stating that specialised cells have specific functions, limited to six named examples — ciliated cells (movement of mucus in the trachea and bronchi), root hair cells (absorption), palisade mesophyll cells (photosynthesis), neurones (conduction of electrical impulses), red blood cells (transport of oxygen), and sperm and egg cells or gametes (reproduction); and describing the meaning of the terms cell, tissue, organ, organ system and organism, as illustrated by the examples given in the syllabus. There is no Supplement content within 2.1 — every outcome above applies to both Core and Extended candidates.
• 2.2 Size of specimens (Core) — stating and using the formula magnification = image size ÷ actual size, and calculating magnification and the size of biological specimens using millimetres as units; (Supplement) converting measurements between millimetres (mm) and micrometres (μm).

The topic also asks candidates to describe what the terms cell, tissue, organ, organ system and organism actually mean, using the syllabus’s own examples. In outline: a cell is the basic structural and functional unit of a living organism; a tissue is a group of cells with similar structures working together to perform a shared function; an organ is made of several tissues working together to perform specific functions; an organ system is a group of organs with related functions working together; and an organism is an individual living thing capable of carrying out all the life processes, built from one or more organ systems. This hierarchy — cell, tissue, organ, organ system, organism — is a short-answer favourite precisely because it is easy to learn imprecisely; candidates who can only recite the five words without being able to apply the definitions to an unfamiliar example (identify which level of organisation a described structure belongs to) tend to lose marks that a slightly more careful revision pass would have kept.

How to approach it

Start by building a single, precise table of the plant-cell, animal-cell and bacterial-cell structures rather than three separate lists — the exam regularly asks candidates to identify what a plant cell has that an animal cell doesn’t (chloroplasts, a cell wall, a permanent vacuole) and what a bacterial cell has that neither of them does (circular DNA, plasmids, no true nucleus), and answers that compare directly score better than answers that describe each cell type in isolation. The six specialised cells are a frequent source of short-answer questions (“name a cell adapted for X and explain how”), and the syllabus’s own function wording is precise enough that it pays to learn it exactly as written — “conduction of electrical impulses” for neurones, not a vaguer paraphrase like “sending messages,” since markers are checking for the specific idea, not just the general topic. For the magnification calculations in 2.2, the single most common way marks are dropped is a units mismatch: image size measured in millimetres against a scale bar given in micrometres, or vice versa, without converting first. Extended candidates should practise the mm-to-μm conversion (1 mm = 1000 μm) until it is automatic, since a question can supply data in either unit and expect the answer in the other. Because this topic underpins so much of the rest of the syllabus, it is worth treating fluency here — naming a structure from a diagram instantly, stating its function without hesitation — as a prerequisite to later topics rather than content to revisit only before the final exam. If your course includes practical microscopy work, connect it directly to this topic rather than treating it as a separate skill: examiners can present a genuine micrograph or a drawing based on one and ask candidates to identify structures, estimate size using a scale bar, or calculate magnification from a stated actual size, so practice should include real or simulated images rather than only labelled textbook diagrams, which tend to be cleaner and easier to read than anything that appears on an actual paper. It is also worth rehearsing the cell/tissue/organ/organ system/organism hierarchy against examples the syllabus has not already given you — for instance being able to say where a leaf, a nephron or a red blood cell sits in that hierarchy — since Cambridge examiners routinely test definitions by asking candidates to apply them to a new context rather than simply recall them.

Official syllabus

Cambridge IGCSE Biology 0610 syllabus for 2026, 2027 and 2028 — cambridgeinternational.org.