What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration?
Terrestrial organisms have the advantage of obtaining oxygen directly from the atmosphere for respiration. Aquatic organisms, on the other hand, need to use oxygen dissolved in water.
Terrestrial animals can breathe the oxygen present in the atmosphere directly. However, animals that live in water need to extract the oxygen that is dissolved in water, which requires specialised organs and mechanisms.
Explanation
The textbook clearly states that 'Terrestrial animals can breathe the oxygen in the atmosphere, but animals that live in water need to use the oxygen dissolved in water.' This is the fundamental advantage - atmospheric oxygen is directly accessible to terrestrial organisms, while aquatic organisms must rely on dissolved oxygen which is limited and requires specialized respiratory structures like gills to extract.