Pearson Edexcel International A Level · Biology (YBI11)

Respiration and Respiratory Quotient: Practice Questions

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

10 questions25 marksFree, no account

Question 1

1 mark

During the contraction of skeletal muscle, which ion binds to troponin to cause a conformational change in tropomyosin, exposing the myosin-binding sites on actin?

Question 2

1 mark

During an experiment investigating the respiration of germinating seeds, it was found that the volume of \(CO_2\) produced was \(14.0\text{ cm}^3\) and the volume of \(O_2\) consumed was \(17.5\text{ cm}^3\). Calculate the respiratory quotient (RQ).

Question 3

1 mark

In the mammalian kidney, the loop of Henle acts as a countercurrent multiplier. Which of the following correctly describes the function of the ascending limb?

Question 4

1 mark

Which of the following terms describes a pair of muscles that work together to produce movement at a joint, where one muscle contracts while the other relaxes?

Question 5

1 mark

According to the sliding filament theory of muscle contraction, which of the following events is triggered by the binding of a new ATP molecule to the myosin head?

Question 6

2 marks

What is the primary role of the sinoatrial node (SAN) in coordinating the mammalian heartbeat?

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Question 7

4 marks

Explain the importance of the brief delay caused by the atrioventricular node (AVN) during the cardiac cycle.

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Question 8

6 marks

Describe the mechanism by which Antidiuretic Hormone (ADH) increases the reabsorption of water in the collecting duct of the kidney.

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Question 9

3 marks

Skeletal muscles are composed of different types of muscle fibres adapted for specific types of activity.

(a) Compare fast-twitch and slow-twitch muscle fibres in terms of their myoglobin content and mitochondrial density.

(b) Which fibre type would be more prevalent in the leg muscles of a marathon runner?

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Question 10

5 marks

The kidney plays a vital role in excretion and osmoregulation.

(a) Explain how the Loop of Henle acts as a countercurrent multiplier to allow the production of concentrated urine.

(b) Describe the effect of antidiuretic hormone (ADH) on the collecting duct when the blood plasma concentration is high.

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