Gaseous movement into and out of the plants occurs indirectly through

$A$: Diffusion of carbon dioxide is $20$ times faster than oxygen.
$R$: It is due to difference in partial pressure as well as solubility of diffusing gases.

In rabbits,which part of the lungs is responsible for the exchange of gases?

What is the primary reason why mountaineers experience difficulty at high altitudes?

Which surface of a plant leaf is better adapted for gas exchange?

In humans,where does the exchange of gases take place?