AQA A Level · Biology 7402

Lipids: Practice Questions

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

10 questions25 marksFree, no account

Question 1

1 mark

Which statement correctly describes the formation of a triglyceride molecule?

Question 2

1 mark

Which of the following correctly describes a structural difference between triglycerides and phospholipids and its effect on their behavior in water?

Question 3

1 mark

A specific triglyceride is composed of three identical unsaturated fatty acids. If each fatty acid contains exactly two double bonds between carbon atoms, how many hydrogen atoms are present in the hydrocarbon chain of one of these fatty acids compared to a saturated fatty acid of the same chain length (n)?

Question 4

1 mark

Which of the following best describes the structural difference between a triglyceride and a phospholipid?

Question 5

1 mark

Which of the following properties of triglycerides is a direct result of their high ratio of carbon-hydrogen bonds to carbon atoms compared to other carbohydrates?

Question 6

2 marks

Compare triglycerides and phospholipids by identifying the specific component that is present in a phospholipid but absent in a triglyceride, and explain how this difference affects the molecule's interaction with water.

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Question 7

3 marks

Describe how the R-group of a fatty acid determines whether it is classified as saturated or unsaturated.

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Question 8

2 marks

Identify the specific chemical bond formed between a molecule of glycerol and a fatty acid during the synthesis of a triglyceride, and name the process by which this bond is broken.

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Question 9

5 marks

Lipids serve various roles in biological systems, ranging from energy storage to structural components.

a) Name the chemical bond formed between glycerol and a fatty acid during the synthesis of a triglyceride. (1 point)
b) Describe the structural difference between a saturated fatty acid and an unsaturated fatty acid. (1 point)
c) Explain how the structure of a phospholipid molecule makes it suited for its role in forming the bilayer of cell-surface membranes. (3 points)

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Question 10

8 marks

Triglycerides and phospholipids are both vital biological molecules formed through condensation reactions.

a) Describe the chemical synthesis of a single triglyceride molecule. Your answer should identify the specific monomers involved and the name of the chemical bond formed. (3 points)

b) Contrast the structure of a phospholipid with that of a triglyceride and explain how this structural difference allows phospholipids to form a bilayer in cell-surface membranes. (3 points)

c) A scientist is investigating a newly discovered fat. They perform an emulsion test. Describe the steps of this test and the observation that would indicate a positive result for the presence of lipids. (2 points)

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