Gases diffuse over the respiratory surface because of `PO_(2)`

Gasses diffuse over the respiratory surface because of

Name the respiratory gases.

Diffusion of gases along the respiratory surface occurs because

Insect moves over surface of water because of a

The respiratory medium flows unidirectionally over the respiratory surface in the gas-exchange systems of:

The respiration medium flows unidirectionally over the respiratory surface in the gas-exchange systems of