Cambridge IGCSE · Biology (0610)

Enzymes: Practice Questions

5 multiple-choice questions marked as you go, and 5 written questions with worked solutions. All on Enzymes.

10 questions24 marksFree, no account

Question 1

1 mark

Why are enzymes essential for all living organisms?

Question 2

1 mark

Which of the following best explains enzyme specificity?

Question 3

1 mark

The specificity of an enzyme is a fundamental property of its function. Which of the following best explains why an enzyme only acts on one particular substrate?

Question 4

1 mark

What type of biological molecule are all enzymes composed of?

Question 5

1 mark

Which statement explains why an enzyme-controlled reaction slows down when the pH is changed significantly away from the optimum?

Question 6

2 marks

Name the two smaller chemical units that combine to form the sub-units (monomers) from which all enzyme molecules are synthesised.

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Question 7

3 marks

Explain the effect of pH on enzyme activity with reference to the shape of the active site.

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Question 8

5 marks

Explain the increase in enzyme-controlled reaction rates as temperature increases towards the optimum, using the concept of kinetic energy.

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Question 9

4 marks

Enzymes are vital biological catalysts found in all living organisms.

(a) Define the term enzyme.
(b) State the specific term for the part of an enzyme molecule that binds to its substrate during a chemical reaction.
(c) State the type of chemical bond or primary building block that constitutes an enzyme molecule.

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Question 10

5 marks

A student investigated the effect of pH on the activity of a protease enzyme found in the human stomach. The results showed that the enzyme worked fastest at \(pH\text{ 2.0}\).

(a) Using your knowledge of enzyme action, explain why the rate of reaction decreases significantly if the pH is increased to \(pH\text{ 9.0}\).
(b) In terms of the lock and key hypothesis, describe what happens to the substrate when it successfully collide with the enzyme's active site.

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