Animals survive by eating plants and other animals for food. Food is broken down into smaller and smaller units and then it is stored in the animal’s body. What kind of energy do animals store to keep their bodies functioning?

Animals store some energy as a more stable complex of many glucose molecules called glycogen. Animals also store some energy as fat, which has more energy for its weight than starches, and therefore is easier to carry around. Energy is broken down from its stored forms into glucose to be transported through the body.

Explanation:

this process is called "phosphorylation." a phosphate bond joins adenosine diphosphate to form adenosine triphosphate.

not necessarily. higher fitness requires the organism to be reproductive successful. for example, an organism at age 10 with 15 offspring is much more fit than an organism at age 15 with only 5 offspring.