A-LevelBiologyTransport in mammals9700/23 · May/June 2022 · Q19 Marks

The trachea of the gas exchange system branches into two airways, each of which enters a lung.

(a)Name the airways that branch from the trachea to enter the lungs.[1]
(b)The lower part of the trachea receives blood from arteries that branch from the aorta. Different arteries carry blood from the heart to the alveoli of the lungs. State the differences between the arteries supplying the lower part of the trachea and the arteries that supply blood to the alveoli of the lungs.[2]
(c)(i)In Fig. 1.1, one of the tissues in the trachea is labelled T. Describe the structural features of tissue T visible in Fig. 1.1.[3]
(c)(ii)Identify structure X in Fig. 1.1 and outline the features that helped your identification. structure X =[3]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.

Mark scheme

Marking points from the official mark scheme (May/June 2022). The mark or mark type is shown in brackets.

[1] bronchi; A bronchus
[2] any two from: trachea v alveoli trachea (carries) oxygenated blood A (carries) blood with more oxygen lower concentration of carbon dioxide blood at higher pressure (part of the) systemic circulation branch from the aorta / (originates) from, left ventricle V alveoli (carries) deoxygenated blood ; A described A (carries) blood with, less / little, oxygen I no oxygen higher concentration of carbon dioxide ; blood at lower pressure ; (part of the) pulmonary circulation or pulmonary artery or from right ventricle (of heart);
[3] allow from, labelled/annotated, diagrams drawn any three from: ciliated epithelium / ciliated epithelial cells / ciliated cells / cells with cilia ; detail (of ciliated epithelial cells); e.g. columnar / description cilia, only facing the lumen / on apical lumen / lining the lumen I on surface of tissue goblet cells; AVP; e.g. basement membrane pseudostratified (epithelium) large nuclei I visible / clear, nuclei basal nuclei (in goblet cells) nucleoli visible within nuclei
[3] blood vessel / capillary / venule ; plus two from: presence of red blood cells (in the lumen); endothelium / endothelial cells ; A flat cells accept for endothelial cell A cells with, prominent / bulging / AW, nucleus very thin / one cell thick, walls ; ref. to small size, qualified ; e.g. narrow lumen / comparison to other tissues alternative endothelium / endothelial cell; plus two from flat cells; cells with, prominent / bulging / AW, nucleus ; one cell thick;