Question 1
Paper 4 short-answer style1 markState what is meant by ingestion. (1 mark)
Model answer
Ingestion is the taking of food (and drink) into the body, through the mouth.
Why this scores
One mark for 'taking food into the body'.
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Detailed notes on Human Nutrition for Cambridge IGCSE Biology, covering key concepts, explanations, examples, and exam-focused revision points.
From mouth to anus: ingestion, digestion, absorption, assimilation, egestion. Cambridge wants the order, the organs, and the role of each.
Mapped to the Cambridge IGCSE 0610 syllabus (2026-2028).
From swallowing to pooping — five distinct steps the syllabus lists by name.
1. INGESTION — taking food and drink into the body via the mouth.
2. DIGESTION — breaking large molecules into smaller, SOLUBLE ones.
3. ABSORPTION — small soluble molecules pass FROM the gut INTO the blood (or lymph for fats). Mostly in the small intestine.
4. ASSIMILATION — body cells take up and USE the absorbed nutrients (e.g. amino acids made into new proteins; glucose used for respiration).
5. EGESTION — passing UNDIGESTED material out as faeces.
Worked qualitative. Are these the same: egestion vs excretion?
Cambridge tip. Memorise the five stages in ORDER. Cambridge often asks "place these in order" or "give the term for…".
From top: mouth, oesophagus, stomach, small intestine, large intestine, anus. Plus accessories: liver, pancreas, gall bladder.
1. Mouth (buccal cavity).
2. Oesophagus (gullet).
3. Stomach.
4. Small intestine (duodenum + ileum).
5. Large intestine (colon + rectum + anus).
Accessory organs (food doesn't pass through, but they help).
| Organ | Secretion | Main action |
|---|---|---|
| Mouth | Saliva (amylase) | Chews food; starts starch → maltose |
| Oesophagus | — | Peristalsis moves the bolus down |
| Stomach | Gastric juice (HCl + pepsin) | Kills bacteria; protein → polypeptides; churns to chyme |
| Liver | Bile | Emulsifies fat (not an enzyme) |
| Pancreas | Pancreatic juice (amylase, protease, lipase) + bicarbonate | Completes digestion; neutralises acid |
| Small intestine | Wall enzymes (e.g. maltase) | Finishes digestion; absorbs via villi |
| Large intestine | — | Absorbs water; forms faeces |
Worked qualitative. Why is the small intestine so long?
Cambridge tip. When asked "where does digestion happen?", say BOTH stomach AND small intestine. Many students say "stomach only".
Alternating contraction of two muscle layers — squeezes food along the gut.
The two muscle layers in the gut wall:
The wave. Behind a bolus of food:
In front of the bolus:
The wave runs all the way from mouth to anus.
Why fibre helps.
Worked qualitative. Why can astronauts swallow food in zero gravity?
Cambridge tip. Always describe BOTH muscles in BOTH conditions (contracted/relaxed) for full marks. "The muscles squeeze food along" earns 1; the full mechanism earns 3.
Verbatim phrases and definitions Cambridge mark schemes credit.
Digestive system appears Paper 2 (5-7 marks: name organs / their functions) and Paper 4 (8-10 marks: explain a process). Examiner reports flag students confusing egestion with excretion, calling bile an enzyme, and missing the small intestine for digestion.
Sources: Cambridge IGCSE Biology 0610 syllabus 2026-2028 (7.2); 0610/22 Oct/Nov 2024 — Q4 (digestive system); 0610 Examiner Reports 2022-2024. Last reviewed 2026-05-07.
Step-by-step solutions to past-paper-style questions on digestive system, written exactly the way a tutor would explain them at the board.
Question
Define the five stages of nutrition: ingestion, digestion, absorption, assimilation, egestion.
Step-by-step solution
Step 1
Ingestion: taking food and drink into the body (through the mouth).
Step 2
Digestion: breaking large insoluble molecules into small SOLUBLE ones — by physical and chemical means.
Step 3
Absorption: digested nutrients moving from the gut into the BLOOD (mainly in the small intestine).
Step 4
Assimilation: cells use the absorbed nutrients (e.g. amino acids → new proteins).
Step 5
Egestion: passing UNDIGESTED material out of the body as faeces.
Answer
Ingestion (eat) → digestion (break down) → absorption (gut → blood) → assimilation (cells use) → egestion (faeces).
Question
Name the organ that: (a) stores bile; (b) produces hydrochloric acid; (c) absorbs most of the water from the remaining material; (d) is where most absorption of digested food happens.
Step-by-step solution
Step 1
(a) Stores bile → gall bladder.
Step 2
(b) Produces hydrochloric acid → stomach.
Step 3
(c) Absorbs most of the remaining water → large intestine (colon).
Step 4
(d) Where most absorption happens → small intestine.
Answer
(a) Gall bladder; (b) stomach; (c) large intestine; (d) small intestine.
Examiner tip
The liver MAKES bile; the gall bladder STORES it. The small intestine is for absorption; the large intestine absorbs the remaining water.
Question
Give the function of: salivary glands, oesophagus, stomach, pancreas, liver, gall bladder, small intestine and large intestine.
Step-by-step solution
Step 1
Salivary glands: secrete saliva containing amylase (digests starch); saliva also moistens food.
Step 2
Oesophagus: tube carrying food from mouth to stomach by peristalsis.
Step 3
Stomach: secretes HCl and protease (pepsin); churns food; begins protein digestion.
Step 4
Pancreas: secretes pancreatic juice (amylase, protease, lipase) into the small intestine.
Step 5
Liver: makes bile; processes the absorbed nutrients. Gall bladder: stores bile and releases it into the small intestine.
Step 6
Small intestine: completes digestion and absorbs digested nutrients into the blood. Large intestine: absorbs the remaining water and forms faeces.
Answer
Salivary glands → amylase. Oesophagus → peristalsis. Stomach → HCl + protease. Pancreas → digestive enzymes. Liver → bile + processing. Gall bladder → bile storage. Small intestine → digestion + absorption. Large intestine → water absorption.
Question
Describe the order of the parts of the alimentary canal that a piece of food passes through, from mouth to anus.
Step-by-step solution
Step 1
Food is taken in at the mouth, chewed and mixed with saliva.
Step 2
It is swallowed and pushed down the oesophagus by peristalsis into the stomach, where it is churned with acid and protease.
Step 3
It passes into the small intestine (duodenum then ileum), where digestion is completed and digested food is absorbed.
Step 4
Undigested material passes into the large intestine (colon), where water is absorbed; faeces are stored in the rectum and egested through the anus.
Answer
Mouth → oesophagus → stomach → small intestine → large intestine (colon) → rectum → anus.
Examiner tip
Cambridge expects the correct order. The liver, pancreas and gall bladder are associated organs but food does not pass through them.
Question
Describe peristalsis and explain how it moves food along the gut.
Step-by-step solution
Step 1
The gut wall has two layers of muscle: an inner CIRCULAR layer and an outer LONGITUDINAL layer.
Step 2
Behind a ball (bolus) of food, the circular muscle CONTRACTS, squeezing the gut narrower and pushing the food forward.
Step 3
Ahead of the bolus, the circular muscle relaxes (and the longitudinal muscle contracts), so the gut widens to receive the food.
Step 4
This wave of contraction and relaxation passes along the gut, moving food from mouth to anus. Dietary fibre provides bulk for the muscles to grip.
Answer
Alternating contraction of the circular and longitudinal muscles in the gut wall produces a wave that pushes food along. Fibre provides bulk that helps the muscles move the food.
Question
Explain the difference between egestion, excretion and assimilation, giving an example of each.
Step-by-step solution
Step 1
Egestion is the removal of undigested food (faeces) that has passed through the gut but never entered the body's cells — e.g. cellulose fibre leaving in the faeces.
Step 2
Excretion is the removal of the waste products of metabolism made inside cells — e.g. urea (from the liver) removed by the kidneys, or carbon dioxide removed by the lungs.
Step 3
Assimilation is the use of absorbed nutrients by the body's cells — e.g. amino acids being built into new proteins, or glucose being used in respiration.
Step 4
So egestion removes material that never entered cells, excretion removes waste made by cells, and assimilation is cells putting nutrients to use.
Answer
Egestion = removing undigested food (faeces). Excretion = removing metabolic waste made in cells (e.g. urea, CO₂). Assimilation = cells using absorbed nutrients (e.g. amino acids → proteins).
Examiner tip
The classic trap is calling egestion 'excretion'. The origin of the material is the key: never-absorbed food vs waste made in cells.
High-scoring sample answers for digestive system on the Cambridge IGCSE 0610 paper, with examiner-style notes mapping each response to the mark scheme and assessment objectives.
State what is meant by ingestion. (1 mark)
Model answer
Ingestion is the taking of food (and drink) into the body, through the mouth.
Why this scores
One mark for 'taking food into the body'.
State the function of (a) the stomach and (b) the large intestine. (2 marks)
Model answer
(a) The stomach churns food and secretes hydrochloric acid and protease (pepsin), beginning the digestion of protein. (b) The large intestine absorbs the remaining water from the undigested material, forming faeces.
Why this scores
One mark each. Stomach: acid/protease/protein digestion or churning; large intestine: absorbs water.
Define the terms digestion, absorption and assimilation. (3 marks)
Model answer
Digestion is the breakdown of large, insoluble food molecules into small, soluble molecules. Absorption is the movement of these digested food molecules (and water) from the gut into the blood (and lymph). Assimilation is the use of the absorbed food molecules by the body's cells, for example building amino acids into new proteins.
Why this scores
One mark each. Digestion = large insoluble → small soluble; absorption = gut into blood; assimilation = cells using nutrients.
Describe what happens to food as it passes through the stomach and then the small intestine. (4 marks)
Model answer
In the stomach, the food is churned by muscular contractions and mixed with hydrochloric acid and protease (pepsin), which begins the digestion of protein (the acid also kills many bacteria). The partly digested food then passes into the small intestine, where bile emulsifies fats and enzymes from the pancreas and intestinal wall complete the digestion of carbohydrates, proteins and fats into small soluble molecules. These digested molecules are then absorbed through the wall of the small intestine into the blood.
Why this scores
Four marks: stomach churns/acid/protease begins protein digestion; food moves to small intestine; enzymes (and bile) complete digestion; products absorbed.
Explain how peristalsis moves food along the gut. (5 marks)
Model answer
The wall of the gut contains two layers of muscle: an inner circular muscle layer and an outer longitudinal muscle layer. Behind a ball of food (bolus), the circular muscles contract, narrowing the gut and squeezing the food forwards. In front of the bolus, the circular muscles relax (and the longitudinal muscles contract), so the gut widens to receive the food. This pattern produces a wave of muscular contraction that passes along the gut, pushing the food from the mouth towards the anus. Dietary fibre adds bulk that the muscles can grip, making peristalsis more effective.
Why this scores
Five marks: two muscle layers (circular and longitudinal); circular muscle contracts behind the food; relaxes in front; wave of contraction pushes food along; role of fibre/bulk.
Describe the roles of the liver, the pancreas and the gall bladder in the digestion of food. (6 marks)
Model answer
The liver makes bile, an alkaline fluid that helps in fat digestion; the liver also processes the nutrients that have been absorbed from the gut. The gall bladder stores the bile made by the liver and releases it through the bile duct into the small intestine, where the bile emulsifies fats — breaking large fat droplets into many small ones to increase the surface area for lipase — and neutralises the acid from the stomach to give a suitable pH for the enzymes. The pancreas makes pancreatic juice, which contains the enzymes amylase, protease (trypsin) and lipase; this juice is released into the small intestine, where the enzymes digest starch, protein and fat respectively into small soluble molecules. Together these three organs supply the bile and enzymes needed to complete digestion in the small intestine.
Why this scores
Up to 6 marks: liver makes bile/processes nutrients; gall bladder stores and releases bile; bile emulsifies fat and neutralises acid; pancreas makes pancreatic juice; juice contains amylase/protease/lipase; acts in the small intestine.
Definitions to memorise and the exact keywords mark schemes credit for digestive system answers — sharpened from recent examiner reports for the 2026 0610 sitting.
Taking food into the body (the act of eating/drinking).
Breaking down large insoluble food molecules into smaller soluble ones — by physical and chemical means.
The movement of digested nutrients from the gut into the blood / lymph (mainly in the small intestine).
Using absorbed nutrients in body cells (e.g. amino acids → new proteins; glucose → respired).
Removal of UNDIGESTED material from the body as faeces.
Wave of muscular contraction in the gut wall that pushes food along — circular and longitudinal muscles work in alternation.
The traps other students keep falling into on digestive system questions — taken from recent Cambridge IGCSE 0610 examiner reports and mark schemes — and how to avoid them.
Why it happens
Both involve removing waste.
How to avoid it
Egestion: getting rid of UNDIGESTED food (faeces). Excretion: getting rid of metabolic WASTE made by cells (urea, CO₂). Different sources.
Why it happens
It's part of the gut, so students assume.
How to avoid it
Digestion is essentially complete by the time food reaches the large intestine, which mainly absorbs WATER.
Why it happens
Bile helps digest fat.
How to avoid it
Bile is NOT an enzyme. It EMULSIFIES fat (breaks big drops into smaller ones, increasing surface area for lipase). Lipase is the enzyme.
The things students keep getting wrong in this sub-topic, answered.