Concerning catabolism and anabolism, A. they refer to reactions solely dealing with the metabolism of lipids. B. the intermediates of one serve as the reactants in the other. C. the energy gathered in one is utilized in the other. D. they refer solely to the reactions involved in synthesis of carbohydrates. E. the intermediates of one serve as the reactants in the other AND the energy gathered in one is utilized in the other.

The correct answer is E. "the intermediates of one serve as the reactants in the other AND the energy gathered in one is utilized in the other."

Here's why:

A. This is incorrect because catabolism and anabolism refer to all metabolic reactions, not just those involving lipids.

B. This is partially correct. Catabolism breaks down molecules into smaller units, producing energy, while anabolism uses this energy to build up larger molecules. So, the products of catabolism can indeed serve as the reactants in anabolism.

C. This is also partially correct. The energy released in catabolic reactions is indeed used in anabolic reactions.

D. This is incorrect because, like A, catabolism and anabolism refer to all metabolic reactions, not just those involving carbohydrates.

E. This is correct because it combines the correct parts of B and C. The intermediates of catabolic reactions serve as the reactants in anabolic reactions, and the energy gathered in catabolic reactions is utilized in anabolic reactions.