Fig. 1.1 presents two photomicrographs of a trachea cross-section. The image on the left is marked low magnification, while the one on the right is marked high magnification.
(a)[1]
State a gas whose concentration is greater in expired air than in inspired air.
(b)[4]
Describe and explain what the structures or substances marked B to E in Fig. 1.1 do. Refer to the letters in Fig. 1.1 in your response.
(c(i))[2]
Put the events shown in Fig. 1.2 into the correct order. Two have already been completed for you.
(c(ii))[2]
Suggest the reason alveoli have thin walls.
(d)[3]
Explain the reason.
Worked solution & mark scheme
This 12-mark question has a full step-by-step worked solution and mark scheme. One marking point: “The gas is carbon dioxide / CO2.” …