Cambridge International A Level · Biology (9700)

Energy and respiration: Practice Questions

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

10 questions25 marksFree, no account

Question 1

1 mark

Which of the following is an anabolic reaction that requires energy from ATP?

Question 2

1 mark

The equation for the aerobic respiration of a lipid is shown:
\( 2C_{51}H_{98}O_6 + 145O_2 \rightarrow 102CO_2 + 98H_2O \)
What is the Respiratory Quotient (RQ) for this lipid, rounded to two decimal places?

Question 3

1 mark

Which statement correctly explains why the decarboxylation reactions of the link reaction and Krebs cycle cease under strictly anaerobic conditions in human skeletal muscle?

Question 4

1 mark

What is the role of coenzyme A in aerobic respiration?

Question 5

1 mark

Which statement explains why lipids have a higher energy value per unit mass than carbohydrates as respiratory substrates?

Question 6

2 marks

Identify the specific locations within a eukaryotic cell where the link reaction and the Krebs cycle take place.

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Question 7

3 marks

Define the Respiratory Quotient (RQ) and state what an RQ value of \( 0.7 \) suggests about the respiratory substrate being used by a cell.

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Question 8

6 marks

Explain how rice plants are adapted to survive in flooded fields where oxygen concentration is low, focusing on the role of aerenchyma and ethanol fermentation.

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Question 9

4 marks

During anaerobic respiration, the pathways taken by pyruvate differ between organisms.
(a) Contrast the end products produced by yeast cells and mammalian muscle cells during anaerobic respiration.
(b) Explain the importance of regenerating NAD during these anaerobic pathways.
(c) State the total net yield of ATP molecules produced per molecule of glucose respired anaerobically.

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Question 10

5 marks

The data below was collected using a respirometer to determine the Respiratory Quotient (RQ) for a sample of germinating seeds:
Volume of oxygen absorbed: \( 20.0\text{ cm}^3 \)
Volume of carbon dioxide produced: \( 14.4\text{ cm}^3 \)
(a) Calculate the RQ for these seeds. Show your working.
(b) Identify the respiratory substrate that gives an RQ value closest to this result.
(c) Explain the biochemical reason why lipids yield significantly more energy than carbohydrates per unit mass.

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