(a)[3]
Complete Table 6.1 to show the features of the human gas exchange system. Put a tick (✓) where a feature is present and a cross (✗) where it is absent.
(b)[3]
Smoking leads to alterations in the lining of the bronchi that make smokers more prone to bacterial infection. Describe these alterations and explain how they increase the risk of bacterial infection.
(c)[4]
Haemoglobin takes up oxygen in the lungs to form oxyhaemoglobin. Describe what makes oxygen be released from the oxyhaemoglobin as blood passes through respiring tissues.
(d)[1]
Explain why red blood cells are found in blood but not in tissue fluid.