Cambridge IGCSE · Science - Combined (0653)

Gas exchange in humans: Practice Questions

5 multiple-choice questions marked as you go, and 5 written questions with worked solutions. All on Gas exchange in humans.

10 questions27 marksFree, no account

Question 1

1 mark

Which statement correctly describes a characteristic of the gas exchange surface in the human lungs that helps maintain a steep concentration gradient?

Question 2

1 mark

Why does the rate and depth of breathing increase during physical activity?

Question 3

1 mark

Which feature is not characteristic of the gas exchange surfaces in the human lungs (alveoli)?

Question 4

1 mark

The graph shows the volume of air in a person's lungs over a period of 20 seconds. Based on the data, what is the ventilation rate (the total volume of air breathed in one minute) for this individual?

Question 5

1 mark

Which row correctly describes the actions of the diaphragm and the external intercostal muscles during inspiration (breathing in)?

Question 6

3 marks

Identify two structural features of the alveoli that adapt them for the efficient exchange of gases in the human lungs.

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Question 7

5 marks

The diagram shows a cross-section of the lining of the trachea. Identify the two types of specialized cells labeled and explain how their structures protect the gas exchange surfaces from pathogens.

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Question 8

3 marks

A student at rest has a breathing rate of \(12\) breaths per minute. During a short race, the rate increases to \(30\) breaths per minute. Calculate the percentage increase in the breathing rate and suggest why the depth of breathing also increases during exercise.

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Question 9

5 marks

A student investigated the effect of exercise on their breathing rate. The data collected was used to produce a graph showing the breathing rate before, during, and after a 5-minute period of intense running.

(a) Using the information in the graph, describe the changes in breathing rate from time \(t = 5\) minutes to \(t = 15\) minutes.

(b) Explain why the breathing rate increases during exercise in terms of energy requirements and cell respiration.

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Question 10

6 marks

Gas exchange in the lungs occurs across the surface of the alveoli. For efficient diffusion, a steep concentration gradient must be maintained between the air in the alveoli and the blood in the capillaries.

(a) Identify the gas that has a higher concentration in the blood than in the alveolar air as blood enters the lung capillaries.

(b) Explain how ventilation and blood flow work together to maintain a steep concentration gradient for oxygen at the gas exchange surface.

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