Efficient gas exchange at the alveoli depends on the properties of the gases themselves as well as on the structure of the membrane they must cross. Evaluate the two statements below on this exchange.

• Statement I: The solubility of CO₂ is 20–25 times higher than that of O₂, so the amount of CO₂ that can diffuse through the diffusion membrane per unit difference in partial pressure is much higher than that of O₂.
• Statement II: The diffusion membrane is made up of three major layers — the thin squamous epithelium of the alveoli, the endothelium of the alveolar capillaries, and the basement substance in between them — and its total thickness is much less than a millimetre.