Question

In public urinals, the urine on standing gives a pungent smell due to
A. Conversion of both urea and uric acid into ammonia
B. Conversion of uric acid into ammonia by ornithine cycle
C. Conversion of urea into ammonia by bacteria
D. None of the above

Answer 1

Urine is a liquid that is a by-product of metabolism in humans and other animals. Urine flows from the kidneys to the urinary bladder through the ureters. The process of excretion of urine from the body through the urethra. Urine is composed of water, salt, chemicals uric acid and urea, electrolytes like phosphorus and potassium. It is produced by kidneys during the filtration of toxins and other bad stuff from the body.

Complete answer:
Fresh urine has no smell and is sterile. When urine is exposed to air, bacteria splits the salts in the urine particularly urea, and urea is converted to ammonia. The pungent smell of urine is due to the presence of ammonia. The presence of unpleasant smells in the fresh urine may be a sign of some urinary tract infection. The ornithine cycle involves the transformation of ammonia to urea for excretion.

Hence, the correct answer is option (C).

Additional information:
-Conversion of urea to ammonia is catalyzed by the enzyme urease.
-Bacteria transform urea to ammonia or ammonium ion and bicarbonate ion.
-Urease is produced by Proteus mirabilis.
-It catalyses the hydrolysis of urea.

Note: Urea is an organic compound that plays a significant role in the metabolism of nitrogen containing compounds by animals. The main nitrogen containing compound in the urine of mammals is urea. Bacteria convert urea into ammonia by urease enzyme. If urea stands for a long time then the bacteria converts it back to ammonia and ammonia produces a pungent smell. Urine can be used as a fertilizer.