Why is this conversion of energy from one molecule to another necessary for all cells?

Actually Welcome to the Concept of the energy conversion

=> ATP can be used to store energy for future reactions or be withdrawn to pay for reactions when energy is required by the cell.

=> When one phosphate group is removed by breaking a phosphoanhydride bond in a process called hydrolysis, energy is released, and ATP is converted to adenosine diphosphate (ADP).

answer: accepted answer: aquatic animals use the oxygen dissolved in water to carry out respiration. since the amount of dissolved oxygen in water is low as compared to the amount of oxygen in the air, therefore the rate of breathing in aquatic animals is much faster than it is in terrestrial animals.

explanation:

not only is it colder, it also becomes darker, less salty, and more dense.