Ammonia, Urea, Uric acid
Ammonia is a small, toxic molecule (NH3) produced by nitrogen ﬁxation or as a metabolic waste product of protein and nucleic acid metabolism
Urea is a soluble nitrogenous waste produced in the liver by a metabolic cycle that combines am- monia with carbon dioxide.
Uric Acid is a product of protein and purine metab- olism and the major nitrogenous waste prod- uct of insects, land snails, and many reptiles. Uric acid is relatively nontoxic and largely insoluble.