IGCSE · Practice questions · The digestive system

Ingest, digest, absorb, assimilate, egest.

Six original Cambridge-style questions on the organs of the digestive system, the path food takes and the five processes of nutrition.

Original questions All questions on this page are original work, written in the Cambridge IGCSE style. They are not from past papers. They test the same concepts and skills the syllabus rewards.

Keep these straight

Tube versus glands.

Alimentary canal: mouth, oesophagus, stomach, duodenum, ileum, colon, rectum, anus.
Associated organs: salivary glands, pancreas, liver, gall bladder; food does not pass through them.
Absorption is into the blood; assimilation is uptake and use by cells.
Egestion removes undigested food; it is not excretion.

Recall

[4 marks]

List, in order, the parts of the alimentary canal that food passes through from the mouth to the anus.

Mouth, oesophagus, stomach. ✓
Duodenum, ileum (small intestine). ✓
Colon, rectum (large intestine). ✓
Anus. (Full marks for the complete correct order; lose one mark for each error.) ✓

Recall

[5 marks]

Define each term: (a) ingestion, (b) digestion, (c) absorption, (d) assimilation, (e) egestion.

(a) Ingestion: the taking of substances, such as food and drink, into the body. ✓
(b) Digestion: the breakdown of food. ✓
(c) Absorption: the movement of nutrients from the intestines into the blood. ✓
(d) Assimilation: the uptake and use of nutrients by cells. ✓
(e) Egestion: the removal of undigested food from the body as faeces. ✓

Explain

[3 marks]

Name the organ that makes bile, the organ that stores it, and the part of the alimentary canal that bile enters.

Made by the liver. ✓
Stored in the gall bladder. ✓
Enters the duodenum (first part of the small intestine). ✓

Analysis

[4 marks]

Four organs are labelled P, Q, R and S on a diagram. P secretes amylase, protease and lipase into the duodenum. Q absorbs most of the digested food. R stores faeces. S carries food to the stomach by peristalsis. Name P, Q, R and S.

P: pancreas. ✓
Q: ileum (small intestine). ✓
R: rectum. ✓
S: oesophagus. ✓

Explain

[2 marks]

A student writes: "Faeces are excreted through the anus." Explain why this is incorrect.

Faeces are mostly undigested food that has never been absorbed into body cells, so their removal is egestion. ✓
Excretion is the removal of waste products of metabolism (such as urea or carbon dioxide) made inside cells. ✓

Data

[3 marks]

A meal took the following times to pass through each region: mouth 1 minute, oesophagus 10 seconds, stomach 3 hours, small intestine 5 hours, large intestine 24 hours. (a) Calculate the total time spent in the stomach and small intestine together, in minutes. (b) Suggest why food stays a long time in the small intestine.

(a) 3 h + 5 h = 8 h = 8 × 60 = 480 minutes. ✓
(b) Chemical digestion is completed there, and there must be enough time for the digested nutrients and most of the water to be absorbed into the blood. ✓

Mark this once you have attempted all six and checked your working. It records a Practiced badge on the topic and adds a one-time bonus. Revealing the solutions alone does not count.