Question

The characteristic that is shared by urea, uric acid and ammonia is/are
A. They are nitrogenous wastes.
B. They all need very large amounts of water for excretion.
C. They are equally toxic.
D. They are produced in the kidney.
(A) A, C and D
(B) A and D
(C) A, C and B
(D) A only

Answer 1

Metabolic wastes must be excreted from the body at intervals or else accumulation of such wastes will increase their concentrations leading to disruption of homeostasis i.e. the chemical and physiological balance of the body.

Complete step by step answer:
Let’s discuss the options and find out the correct answer.
- Ammonia, urea and uric acid are included under nitrogenous wastes. Amino and nucleic acids also consist of urea. During the process of metabolism of amino acids, the nitrogen-containing amino group is removed and converted to ammonia. However, ammonia is very toxic in nature.
- Urea is lesser in toxicity as compared to the other two. Hence, requires the least amount of water for excretion. Ammonia requires a very high amount of water for excretion.
- Among the options given, no compound is equally toxic. Ammonia is the most toxic compound with urea being the least toxic.
- Organisms that cannot excrete nitrogen as ammonia are converted to urea with the help of urea cycle which occurs in the liver.
Hence, option D: A only is the correct answer.

Note: Aquatic animals excrete it into the water before it increases upto a toxic concentration in their tissues.