Gaseous exchange refers to the diffusion of respiratory gases across the respiratory surfaces. The respiratory gases are oxygen and carbon iv oxide gas. The respiratory surfaces vary from organism to organism. They are the actual sites where gases diffuse into and out of the body of the organisms.

Gaseous exchange enables  living organisms to obtain useful gases and remove the waste gases from their  bodies. Plants and animals obtain oxygen which they need for respiration while  giving out carbon IV oxide as a waste gas.Plants utilize the carbon IV oxide produced  from respiration for the process of photosynthesis in presence of light.