IGCSE Biology: Human Nutrition (Cambridge 0610)

Topic 7 of Cambridge IGCSE Biology (0610) covers what a balanced diet supplies, how the alimentary canal breaks food down physically and chemically, and how digested nutrients are absorbed into the blood. It follows on from Topic 6 (Plant nutrition) in the syllabus sequence and reuses ideas from Topic 5 (Enzymes) directly – you cannot answer digestion questions well without already being secure on substrate, product and optimum conditions.

Where this topic sits

Human nutrition spans five sub-topics, 7.1 to 7.5, and is examined on every paper. Core candidates working for grades C-G need the Core statements in each sub-topic; Extended (Supplement) candidates need Core plus Supplement for grades A*-G. The digestive-system labelling and enzyme tables below are some of the most reliably-tested content in the whole syllabus, so they reward careful, precise learning rather than general revision.

7.1 Diet

Core

• Describe what is meant by a balanced diet.
• State the principal dietary sources and describe the importance of: carbohydrates, fats and oils, proteins, vitamins (limited to C and D), mineral ions (limited to calcium and iron), fibre (roughage) and water.
• State the causes of scurvy (vitamin C deficiency) and rickets (vitamin D deficiency).

There is no Supplement-only content in 7.1. The syllabus deliberately restricts vitamins to C and D and mineral ions to calcium and iron – questions will not ask about vitamin A or iron-only topics beyond haemoglobin production, so do not over-revise nutrients outside this list.

7.2 Digestive system

Core

• Identify the main regions of the alimentary canal (mouth, oesophagus, stomach, small intestine – distinguishing duodenum and ileum – large intestine – distinguishing colon and rectum – and anus) and associated organs (salivary glands, pancreas, liver, gall bladder) from a diagram.
• Define and distinguish ingestion, digestion, absorption, assimilation and egestion.

There is no Supplement-only content in 7.2, but this is the sub-topic where precise definitions matter most: egestion (removing undigested food as faeces) is routinely confused with excretion (removing waste made by the body’s own metabolism, covered in Topic 13). Examiners treat this as a distinct, testable confusion, not a minor slip.

7.3 Physical digestion

Core

• Describe physical digestion as the breakdown of food into smaller pieces without chemical change to the food molecules, increasing the surface area for chemical digestion.
• Identify the types of human teeth (incisors, canines, premolars, molars) from diagrams and describe their functions.
• Describe the structure of a tooth, limited to enamel, dentine, pulp, nerves, blood vessels and cement.
• Describe the role of the stomach in physical digestion, limited to churning.

Supplement

• Describe the role of bile in emulsifying fats and oils to increase the surface area for lipase.

Bile’s role is a common source of lost marks because candidates describe it as chemical digestion. Bile does not break any chemical bond in a fat molecule – it only produces smaller droplets from larger ones, which is why it belongs in physical, not chemical, digestion.

7.4 Chemical digestion

Core

• Describe chemical digestion as the breakdown of large, insoluble molecules into small, soluble molecules using enzymes.
• Name the enzymes amylase, protease and lipase, and state the substrate and product(s) of each: amylase converts starch to simple reducing sugars; proteases convert protein to amino acids; lipase converts fats and oils to fatty acids and glycerol.
• Describe the significance of pH on the action of amylase, protease and lipase.
• State the functions of hydrochloric acid in gastric juice: killing harmful microorganisms in food, and providing the acidic pH needed for enzyme activity.

Supplement

• State that amylase breaks down starch to maltose, and maltase (at the epithelium lining of the small intestine) breaks maltose down further to glucose.
• Name pepsin as a protease that works in the acidic conditions of the stomach and trypsin as a protease that works in the alkaline conditions of the small intestine.
• Describe the role of bile in neutralising acidic stomach contents entering the duodenum, producing the alkaline conditions in which intestinal enzymes work best.

The two enzyme tables (7.1’s substrate/product pairs and 7.4’s acid/alkaline protease pairing) are the highest-value pieces of recall in this topic: examiners routinely present an unfamiliar enzyme name or context and expect the substrate-to-product logic to be applied rather than just memorised in isolation.

7.5 Absorption

Core

• State that the small intestine is the region where soluble products of digestion are absorbed into the blood, and that most water is absorbed from the small intestine, with some from the colon.

Supplement

• Describe the small intestine’s internal surface as being folded and covered with villi and microvilli, increasing the surface area for absorption.
• Describe the structure of a villus, limited to a wall one cell thick and a good blood supply, and explain the role of capillaries (absorbing sugars and amino acids) and lacteals (absorbing fatty acids and glycerol, as part of the lymphatic system).

Absorption is often the easiest sub-topic to secure full marks on because it has a short, closed list of structures – but candidates lose marks by describing capillaries and lacteals as absorbing the same products. Learn the split (capillaries: sugars and amino acids; lacteals: fat digestion products) as a fixed pair, the same way diffusion and active transport are learned as a contrasting pair in Topic 3.

How the sub-topics connect

Diet (7.1) supplies the raw materials; the digestive system (7.2) provides the labelled route those materials travel; physical digestion (7.3) increases surface area; chemical digestion (7.4) uses that surface area with enzymes to produce small soluble molecules; and absorption (7.5) is where those molecules finally enter the blood and lymphatic system. A question that looks like it is only testing one sub-topic – for example, why chewing matters – is very often testing whether you can link it forward to the next stage (surface area for enzymes) rather than treating chewing as an isolated fact.

How to approach it

Build the enzyme table (amylase/protease/lipase with substrates and products) and the acid-versus-alkaline protease pairing (pepsin and trypsin) as your two anchor facts, since a large share of exam questions on this topic test one or both directly. Keep egestion and excretion permanently separated in your own notes, since this is one of the most frequently tested definition-confusions in the whole syllabus, not just within this topic. For Extended candidates, be able to redraw a villus from memory and label capillaries and lacteals correctly, since diagram-labelling questions on absorption appear on both Core and Extended papers even though the villus/microvilli detail itself is Supplement-only.

Official syllabus

Cambridge International, Cambridge IGCSE Biology (0610) syllabus for examination in 2026, 2027 and 2028 (Version 3, published August 2026): official syllabus PDF, Subject content, section 7 “Human nutrition”. Verified 2026-09-06.