Question

Nitrogen is excreted in three forms: ammonia, urea and uric acid. How do these different forms differ in their toxicity, amount of water required for excretion and amount of energy required to generate?

Answer 1

Answer )

	Ammonia	Urea	Uric acid
Toxicity	Most toxic	Intermediate Toxic	Least toxic
Amount of water required for excretion	Maximum water requirement	Intermediate water requirement	Least water requirement
Energy required for generation	Least energy	Intermediate	Maximum energy required for generation

During protein breakdown ,Nitrogenous waste products are formed like Ammonia ,Urea and Uric acid .

These are Nitrogenous waste products and need to be eliminated from the body .

First product which is formed is Ammonia which requires lots of water for their Excretion and also it is very toxic so it is converted into Urea in Liver in Mammals .So mammals excrete urea in urine so they are Ureophilic excreting urea in urine .This conversion of Ammonia into Urea through Urea cycle in Liver requires energy in form of ATP so this is energy requiring step but while Excretion in urine amount of water required is less as compared to Ammonia .

In case of Reptiles ammonia is converted into Uric acid as they are uricophilic excrete Uric acid in urine ---> generation of Uric acid is very tedious and requires large amount of ATP (Adenosine triphosphate ) but main advantage is it requires less amount of water for its Excretion .