CourseCourseConceptConcept

CAIE IGCSE Biology 11.1 Gas Exchange in Humans Questions

Practise human gas-exchange questions on airway labels, alveolar diffusion, inspired-expired air, exercise breathing and ventilation mechanics.

Syllabus
2026–2028
Course
Biology 0610

Exam points

  • label the airway from larynx and trachea through bronchi and bronchioles to alveoli
  • identify lungs, ribs, diaphragm, intercostal muscles, alveoli and capillaries in breathing-system diagrams
  • relate alveolar area, thin walls, blood supply and ventilation to rapid gas exchange
  • use limewater to test for carbon dioxide when comparing inspired and expired air
  • compare inspired and expired air using oxygen, carbon dioxide and water-vapour percentages or tables
  • measure or calculate breathing rate and inspired volume before and after exercise from traces or tables
  • identify internal and external intercostal muscles in thorax diagrams
  • explain how tracheal cartilage rings keep the airway open and prevent collapse
  • sequence muscle action, rib and diaphragm movement, thorax volume, pressure and airflow during ventilation
  • explain exercise breathing from rising blood carbon dioxide and brain detection to faster, deeper ventilation
  • explain how goblet-cell mucus traps particles and cilia move contaminated mucus away from gas-exchange surfaces

Covered syllabus points

11.1.1—Features of gas exchange surfaces11.1.2—Following parts of the breathing11.1.3—Differences in composition between11.1.4—Differences in composition between11.1.5—Effects of physical activity on11.1.6—Internal and external intercostal11.1.7—Function of cartilage in the trachea11.1.8—Ventilation mechanics11.1.9—Differences in composition between11.1.10—Link between physical activity11.1.11—Role of goblet cells, mucus

Question 1

[Maximum number: 16]

Question (a)

(a)

Fig. 6.1 shows part of the human gas exchange system.

Fig. 6.1

Fig. 6.1

[ 10 ]

Question (i)

(i)

Table 6.1 shows the names of some parts of the human gas exchange system, their functions and the letters in Fig. 6.1 that identify the parts.

Complete Table 6.1.

Table 6.1

Table 6.1

[ 7 ]

Question (ii)

(ii)

Describe and explain how the alveoli are adapted for gas exchange.

[ 3 ]

Question (b)

(b)

Explain the differences in composition between inspired and expired air.

[ 3 ]

Question (c)

(c)

Physical activity changes the concentration of carbon dioxide in the body.

State where this change is detected and how the body responds to the change.

[ 2 ]

Question (d)

(d)

State the name of a solution that can be used to test for the presence of carbon dioxide gas.

[ 1 ]

Question 2

[Maximum number: 1]

Substances move between blood and tissues at various sites in the circulatory system of mammals.

Oxygen is absorbed into the blood as it passes through the lungs.

State the structures in the lungs where oxygen passes into the blood from the air.

Question 3

[Maximum number: 1]

Which row shows the composition of expired air from a healthy person?

carbon dioxide
\%

oxygen
\%

water vapour

0.04

21

saturated

0.04

16

variable

4

21

variable

4

16

saturated

Question 4

[Maximum number: 3]

Fig. 6.1 shows part of the human gas exchange system.

Fig. 6.1

Fig. 6.1

Describe and explain how the alveoli are adapted for gas exchange.

Question 5

[Maximum number: 1]

State the name of a solution that can be used to test for the presence of carbon dioxide gas.

Question 6

[Maximum number: 2]

Question (a)

(a)

A student measured the rate and depth of breathing of an athlete for 30 seconds at rest. The data are shown in Fig. 3.2.

Fig. 3.2

Fig. 3.2

[ 2 ]

Question (i)

(i)

Using the information in Fig. 3.2, calculate the rate of breathing at rest.

breaths per minute

The measurements were repeated while the athlete was running on a treadmill.
The data are shown in Fig. 3.3.

Fig. 3.3

Fig. 3.3

[ 1 ]

Question (ii)

(ii)

Using the information in Fig. 3.3, calculate the volume of air inspired in one breath from 25 seconds.

dm3\mathrm{dm}^{3}

[ 1 ]

Question 7

[Maximum number: 1]

Fig. 1.1 is a diagram of the gas exchange system in humans.

Fig. 1.1

Fig. 1.1

Draw a label line and the letter X on Fig. 1.1 to identify an external intercostal muscle.

Question 8

[Maximum number: 2]

Fig. 1.1 is a diagram of the gas exchange system in humans.

Fig. 1.1

Fig. 1.1

State the name of the tissue that forms C-shaped structures in the wall of the trachea and state its function.

name

function

Question 9

[Maximum number: 2]

Fig. 1.1 is a diagram of the gas exchange system in humans.

Fig. 1.1

Fig. 1.1

Describe the effects on the thorax of contraction of the diaphragm.

Question 10

[Maximum number: 3]

Explain the differences in composition between inspired and expired air.

Question 11

[Maximum number: 4]

A student measured the rate and depth of breathing of an athlete for 30 seconds at rest. The data are shown in Fig. 3.2.

Fig. 3.2

Fig. 3.2

Explain the effect of exercise on the rate and depth of breathing shown in Fig. 3.2 and Fig. 3.3.

Question 12

[Maximum number: 1]

A scientist measured the number of dust particles in inspired air and in expired air.

They found fewer dust particles in expired air.

Suggest a reason for their observation.

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