The different structures in the human gas exchange system vary in the tissues and types of cell that are present. Figure 1.1 is a photomicrograph showing a section of one of the structures in the human gas exchange system.

Figure 1.1, a photomicrograph of a section through the wall of a gas exchange system structure, showing the folded epithelium with a pale, flask-shaped cell bulging from the epithelial surface labelled A, and a band of elongated spindle-shaped cells beneath the epithelium labelled B; a region of tissue with clusters of rounded cells is visible to the lower right.

Name the cell labelled A in Figure 1.1.

1(a)(ii)Gas ExchangeMedium1 mark

Name the tissue labelled B in Figure 1.1.

1(a)(iii)Gas ExchangeMedium2 marks

Explain why the structure in the human gas exchange system shown in Figure 1.1 is not a bronchiole.

Answer

0 words

1(b)(i)Diffusion Osmosis Membrane TransportMedium2 marks

Several different types of epithelial cell are present in the human gas exchange system. These cells have different surface area to volume ratios (SA : V). A diagram of a columnar epithelial cell is shown in Figure 1.2.

Figure 1.2, a rectangular block diagram of a columnar epithelial cell with an oval nucleus, labelled with a height of $25\,\mu\text{m}$, a width of $8\,\mu\text{m}$ and a depth of $6\,\mu\text{m}$.

The cell in Figure 1.2 has a volume of

1200 μ m^{3}

. Calculate the SA : V of the cell shown in Figure 1.2. Give the value of SA to one significant figure. The value of V is 1.

1(b)(ii)Gas ExchangeEasy2 marks

A squamous epithelial cell has a typical SA : V of 10 : 1. Explain why the high SA : V of a squamous epithelial cell is beneficial for gas exchange.

Answer

0 words