Gas exchange in the lungs and in leavesAQA A-Level Biology: Mind map

Exam questions on Gas exchange in the lungs and in leaves

1. Marram grass grows on sand dunes, where water is scarce and winds are strong. Its leaves are rolled, with the stomata on the inner surface, and the inner surface is lined with hairs. A bean plant, which is a typical dicotyledonous plant, grows in moist soil and has flat leaves.
   Explain how the stomata of the bean plant allow the plant to gain carbon dioxide while limiting the loss of water.2 marks
2. A student dissects the lungs of a sheep to study the gas exchange system, and then uses a model made from a bell jar, a Y-shaped tube and a rubber sheet to show how breathing works. The student also measures the breathing of a volunteer at rest.
   Explain how air enters the lungs during inspiration.2 marks
3. A respiratory clinic treats patients with lung diseases, including pulmonary fibrosis, in which scar tissue thickens the alveolar walls and makes the lungs less elastic. The clinic's researchers also study how smoking affects the risk of lung disease.
   A patient with pulmonary fibrosis has a tidal volume of 300 cm³ and breathes 24 times per minute at rest. Calculate the patient's pulmonary ventilation rate and explain why fibrosis reduces the rate of gas exchange.3 marks