Biology 9700 · AS & A Level · The gas exchange system
The gas exchange system — practice question
Fig. 1.1A shows a photomicrograph of healthy lung tissue.
Fig. 1.1B shows a photomicrograph of lung tissue taken from a person with emphysema, a chronic obstructive pulmonary disease (COPD). Both images are at magnification $30$.
(a)[1]
State the name of the structure marked H in Fig. 1.1A.
(b)[2]
Calculate the actual diameter of the alveolus at X-Y.
Show the formula you use and then complete the calculation.
Give your answer to the nearest whole micrometre ($\mu\text{m}$).
(c)[4]
Gas exchange in the lungs takes place in the alveoli.
Describe the process of gas exchange in healthy lungs and suggest how this differs from gas exchange in the diseased lung shown in Fig. 1.1B.
Worked solution & mark scheme
This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: “bronchiole (respiratory/terminal may come before bronchiole)” …