Q. 1. What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration?
Terresttrial organisms breathe in Oxygen for respiration directly from the environment as opposed to the aquatic organisms who have to use oxygen dissolved in water.
The concentration of dissolved oxygen in water is much lesser than that present in the air and therefore aquatic organisms have to have a much faster breathing rate than terrestrial organisms for the sufficient supply of oxygen.
In the course of evolution aquatic organisms have also developed special body parts for the efficient absorption of oxygen dissolved in water.