Gas exchange: past paper questions
Real questions on gas exchange
The newest 20 of 55 written questions, plus 129 multiple-choice. Open one to see it on the real paper.
- 9700/21 · October/November 2025 · Q6b(i)[2]
Alveolar macrophages are found in contact with squamous epithelial cells in the walls of alveoli. Explain how the cells lining the alveoli are adapted for gas exchange.
See it on the paper → - 9700/21 · October/November 2025 · Q6b(ii)[2]
Describe the role of elastic fibres in the wall of an alveolus.
See it on the paper → - 9700/22 · May/June 2025 · Q2b[5]
A number of substances are involved in the transport of respiratory gases. Complete Table 2.1 by stating the name of the substance that matches the description of its role in the transport of respiratory gases. The first row has been completed for you. Table 2.1 role in the transport of respiratory gases carbon dioxide...
See it on the paper → - 9700/22 · May/June 2025 · Q4d[3]
Fig. 4.1 Blood vessels and some structures of the gas exchange system are visible in Fig. 4.1. On Fig. 4.1, use a label line and label: • • a bronchus a bronchiole (d) Fig. 4.1 is a photomicrograph of a section of lung tissue taken from a person who has not been infected with the bacterial pathogen and who does not hav...
See it on the paper → - 9700/21 · October/November 2024 · Q3a[3]
Fig. 3.1 is a photomicrograph of a transverse section through a region of the wall of the bronchus in the gas exchange system. J K Fig. 3.1 Identify the tissues J and K shown in Fig. 3.1, and suggest how the wall of a bronchiole differs from the wall of the bronchus for these two tissues. J K difference
See it on the paper → - 9700/22 · October/November 2024 · Q2d(ii)[3]
One consequence of the pneumonia that results from P. jirovecii infection is a decrease in the quantity of oxygen that is delivered to body tissues. Explain why a severe P. jirovecii infection results in a decrease in the quantity of oxygen that is delivered to body tissues.
See it on the paper → - 9700/23 · October/November 2024 · Q1a(i)[1]
Use the letters in Fig. 1.1 to identify the parts of the gas exchange system that contain cartilage.
See it on the paper → - 9700/23 · October/November 2024 · Q1a(ii)[2]
Describe the role of cartilage in the gas exchange system.
See it on the paper → - 9700/23 · October/November 2024 · Q1a(iii)[4]
Microscope slides were prepared from two regions of the gas exchange system. Fig. 1.2 and Fig. 1.3 are photomicrographs of the two slides. ×120 Fig. 1.2 ×560 Fig. 1.3 Complete Table 1.1. • Use the letters from Fig. 1.1 to identify the regions of the gas exchange system from which the two slides were prepared. • Identif...
See it on the paper → - 9700/43 · October/November 2024 · Q2b[6]
Fig. 2.1 shows the results of an experiment to monitor this rhythm over three days and nights for the plant Arabidopsis thaliana. The percentage of open stomata is shown. Each day consisted of 14 hours of light (white bar) and each night consisted of 10 hours of darkness (black bar). 100 Key day night open stomata 50 /...
See it on the paper → - 9700/43 · October/November 2024 · Q2c[2]
The experiment was repeated with A. thaliana plants that were left in darkness from 14 to 96 hours. The results are shown in Fig. 2.2. 100 Key 0 day night open stomata 50 / % 0 24 48 time / hours 72 96 Fig. 2.2 With reference to Fig. 2.1, explain what Fig. 2.2 shows about the role of genes and the role of the environme...
See it on the paper → - 9700/21 · May/June 2024 · Q4a(ii)[3]
Describe how the tissue shown in Fig. 4.1 is adapted to its function in the gas exchange system.
See it on the paper → - 9700/23 · May/June 2024 · Q3b(i)[1]
Draw two labelled arrows on Fig. 3.1 to show the direction of movement of oxygen and the direction of movement of carbon dioxide during gas exchange in the lungs.
See it on the paper → - 9700/23 · May/June 2024 · Q3b(ii)[4]
Suggest and explain how a steep oxygen concentration gradient is maintained in the lungs.
See it on the paper → - 9700/22 · February/March 2024 · Q2b[3]
Dromedary camels are classified in the family Camelidae and live in desert habitats of North Africa and Asia. In these hot, dry environments, dromedary camels can lose up to 30% of their body mass from dehydration, causing their blood to become more viscous (thicker). Fig. 2.1 shows a drawing of red blood cells of a dr...
See it on the paper → - 9700/22 · February/March 2024 · Q2c(i)[3]
With reference to Fig. 2.3, explain how the differences between the oxygen dissociation curves for humans and llamas show that llamas are better adapted for living at high altitudes than humans.
See it on the paper → - 9700/22 · February/March 2024 · Q2c(ii)[1]
Sketch a curve on Fig. 2.3 to show the effect of an increased carbon dioxide concentration on the percentage saturation of adult human haemoglobin with oxygen.
See it on the paper → - 9700/22 · February/March 2024 · Q2c(iii)[3]
Explain the importance of the Bohr shift in metabolically active organs, such as the liver.
See it on the paper → - 9700/21 · October/November 2023 · Q3c[3]
Hydrogen bonding is important for movement of water through xylem vessels in a plant. Describe the roles of hydrogen bonding in the movement of water through xylem vessels.
See it on the paper → - 9700/21 · October/November 2023 · Q3d[2]
Water that has travelled through xylem vessels reaches the leaves. Cooling of the leaf occurs as a result of the evaporation of water during transpiration. Water has a high latent heat of vaporisation because water molecules form hydrogen bonds. With reference to hydrogen bonding, suggest why cooling of the leaf occurs...
See it on the paper →
What examiners said
Some candidates showed knowledge of hydrogen bonding between water molecules and were able to use the term cohesion correctly. A few candidates confused the terms cohesion and adhesion. These responses were given partial credit for their knowledge of these terms. The strongest answers explained the importance of cohesion in the transport of water, making reference to a column of water being pulled...
— Examiner report, October/November 2023, 9700/21 Q3(c) (Cambridge)
The highest achieving answers to this question linked knowledge of cohesion between water molecules and knowledge of the high latent heat of vaporisation of water to explain the need for energy to break hydrogen bonds between water molecules. Some candidates were able to gain credit for their descriptions of heat energy being lost from the leaf when water evaporates, even if they needed to explain...
— Examiner report, October/November 2023, 9700/21 Q3(d) (Cambridge)
In this question, it was important to focus on blood flow in the alveolar capillaries so that an explanation could be given about how steep diffusion gradients could be maintained. While there were some very clear, well-expressed answers, many only gave an account of gas exchange or wrote about the features of a good gas exchange surface, which was not required. The most comprehensive answers cove...
— Examiner report, October/November 2023, 9700/22 Q4(a) (Cambridge)
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