Use the line P-Q to determine the actual diameter of the bronchus lumen. State the formula used in your calculation, show all working, and give the final value to the nearest micrometre ($\mu\text{m}$).
In Fig. 2.1, the region marked R contains a section of some alveoli. Name the tissue that forms the lining of the alveolar air spaces.
Suggest how alveoli are adapted for gas exchange.
In plant leaves, both gas exchange and transpiration take place through open stomata. Suggest how the arrangement of cells in the leaf of a dicotyledonous plant contributes to water loss by transpiration.
Describe the information presented in Fig. 2.2.
Suggest why the transpiration rate altered between 09:00 and 10:00.
Describe the information shown in Fig. 2.2.
Suggest why the transpiration rate altered between 09:00 and 10:00.