The diffusion pathway for oxygen from alveolar air to blood passes through

  1. cartilage and smooth muscle
  2. goblet cells
  3. alveolar epithelium and capillary endothelium
  4. the pleural membranes only
Answer

C) alveolar epithelium and capillary endothelium

Two thin cell layers. AS & A Level Biology · Topic 9 Gas Exchange · 9.1 The gas exchange system

Biology MCQ · More A Level Biology: Gas exchange MCQs · Practise