Explain why respiratory surfaces must be moist​

In animals, the process of respiration is aerobic respiration, exchange of gases takes place ( carbon dioxide leaving the cell, oxygen entering)

Single cellular organisms can exchange gases directly across their cell membrane through the process o diffusion.

Large animals cannot maintain gas exchange by diffusion across their outer surface. A respiratory surface is covered with thin, moist epithelial cells that allow oxygen and carbon dioxide to exchange. Those gases can only cross cell membranes when they are dissolved in water or an aqueous solution, thus respiratory surfaces must be moist.

Explanation:

a = executive branch; b = judicial branch