. "ammonia because it is the most soluble of all the nitrogen-containing metabolic waste products uric acid because it does not require water for excretion ??? ??? ??? Many insects, birds, and other reptiles excrete nitrogenous wastes in the form of uric acid, which _____. (see book section: Concept 44.2: An animal's nitrogenous wastes reflect its phylogeny and habitat)" . . .