CAIE IGCSE Biology 7.4 Chemical Digestion Questions

Practise tracing starch, protein and fat digestion through named enzymes, products and gut locations, then connect pH conditions and solubility to nutrient absorption.

Syllabus
2026–2028
Course
Biology 0610

Exam points

  • Define chemical digestion as breaking large insoluble food molecules into small soluble molecules that can be absorbed.
  • Match amylase, proteases and lipase to their substrates and soluble products, and explain enzyme specificity in digestive reactions.
  • Trace where amylase, maltase, pepsin and trypsin act in the digestive system, including the starch and protein pathways.
  • Explain how hydrochloric acid and alkaline bile create suitable pH conditions for proteases and lipase in the stomach and small intestine.

Question 1

[Maximum number: 1]

What is an example of chemical digestion?

A

breaking down starch into reducing sugars

B

churning of food by muscular contractions of the stomach wall

C

grinding of food by teeth

D

mixing of food with bile

Question 2

[Maximum number: 1]

Tissue plasminogen activators (TPAs) are human proteins that are used as drugs to break down blood clots.

TPAs break down blood clots by activating plasminogen. Plasminogen is a protein that is always present in the blood.

When activated, plasminogen forms a protease that breaks down fibrin molecules.

State the products of the action of protease on the protein fibrin.

TPAs can be produced by genetically-engineered bacteria.
Fig. 5.1 shows some of the stages involved in genetically engineering a bacterium to make a TPA.

Fig. 5.1

Fig. 5.1

Question 3

[Maximum number: 7]

Fig. 2.1 is a diagram of the human alimentary canal and associated organs.

Fig. 2.1

Fig. 2.1

Question (a)

(a)

Table 2.1 shows enzymes, the organs that secrete these enzymes, their substrates and products.

Complete Table 2.1.

Table 2.1

Table 2.1

[ 4 ]

Question (b)

(b)

Explain the role of hydrochloric acid in the alimentary canal.

[ 3 ]
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