Q. Consider the following statements:

1. During the breathing cycle in humans, the lungs always retain a residual volume of air ensuring there is sufficient time for the absorption of oxygen and the release of carbon dioxide.
2. Carbon dioxide is less soluble in water than oxygen and therefore is not primarily transported in the dissolved form in blood.

Which of the above statements is / are correct?
Answer: Only 1
Notes: Statement 1 is correct as the lungs maintain a residual volume to facilitate continuous gas exchange. Statement 2 is incorrect because carbon dioxide is in fact more soluble in water than oxygen, allowing a significant portion to be transported in the dissolved form in blood. Oxygen, by contrast, relies primarily on binding to haemoglobin for transport.