Cambridge International A Level · Biology (9700)

Biological molecules: Practice Questions

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

10 questions27 marksFree, no account

Question 1

1 mark

Which type of covalent bond is formed between two amino acids during a condensation reaction to form the primary structure of a protein?

Question 2

1 mark

During strenuous exercise, a mammal loses a significant amount of heat through the evaporation of sweat from its skin. Which property of water is primarily responsible for this effective cooling mechanism?<\/p>

Question 3

1 mark

Which feature of the collagen molecule is essential for its ability to form stable, high-tensile strength fibres?

Question 4

1 mark

A student carries out the emulsion test on an unknown liquid sample. After shaking the sample with ethanol and then adding the mixture to water, a cloudy white layer is observed. Which type of biological molecule is present in the sample?

Question 5

1 mark

In a semi-quantitative Benedict's test, which observation would indicate a higher concentration of reducing sugar in a sample?

Question 6

4 marks

Explain why sucrose is classified as a non-reducing sugar while maltose is a reducing sugar.

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Question 7

5 marks

In a semi-quantitative Benedict's test, explain how the time to first colour change can be used to estimate the concentration of a reducing sugar.

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Question 8

3 marks

Why must a solution be boiled with hydrochloric acid before testing for non-reducing sugars with Benedict’s reagent?

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Question 9

4 marks

Proteins can be classified as globular or fibrous based on their shape and properties. (a) Explain why globular proteins are generally soluble in water while fibrous proteins are not. (b) Give one example of a globular protein and state its primary role in the body.

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Question 10

6 marks

Sucrose is a common disaccharide in plants. (a) Name the two monosaccharides that form sucrose and the type of glycosidic bond that links them. (b) Sucrose is a non-reducing sugar. Explain what this means in terms of the Benedict's test and describe the biochemical steps necessary to obtain a positive result for a sucrose solution.

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