Cambridge International A Level Biology Revision Guide

Chapter 9: Gas exchange and smoking
9 a Copy and complete the table to compare the trachea with a respiratory bronchiole. Use a tick (✓) to
indicate that the structure is present and a cross (✗) to indicate that it is not.
Structure Trachea Respiratory bronchiole
smooth muscle cells
ciliated epithelial cells
mucous glands
cartilage
elastic fibres
[5]
b Describe how the alveoli are protected against infection. [5]
[Total: 10]
10 The composition of alveolar air remains fairly constant even though gases are exchanged with the blood in the
capillaries that surround the alveoli.
a Describe the process of gas exchange between alveolar air and blood. [4]
b Explain why the composition of alveolar air remains fairly constant. [3]
c Suggest three ways in which the gas exchange system responds to the demands of exercise. [3]
[Total: 10]
11 Cigarette smoke contains tar, nicotine and carbon monoxide. Tar contains carcinogens.
a Describe the effect of tar on the lining of the bronchi in the lungs. [8]
b Describe the effects of nicotine and carbon monoxide on the cardiovascular system. [6]
[Total: 14]
12 The figure shows photomicrographs of alveoli from 1 a non-smoker (× 200) and 2 a smoker (× 50).
197
1 2
a Use the photomicrographs to describe how the lungs of this smoker differ from the lungs of the non-smoker. [4]
b Smokers whose lungs contain alveoli similar to those shown in photomicrograph 2 have poor health.
i Describe the symptoms that these people may have. [4]
ii Explain how the structure of the lungs is responsible for this poor health. [3]
[Total: 11]