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Excretory Products And Their Elimination

Question
CBSEENBI11002434

The principal nitrogenous exceretory compound in humans is synthesised

  • in kidneys but eliminated mostly through the liver

  • in kidneys as well as eliminated by kidneys

  • In liver and also eliminated by the same through bile

  • in the liver, but eliminated mostly through the  kidneys

Solution

D.

in the liver, but eliminated mostly through the  kidneys

In humans, the principal nitrogenous excretory compound (i.e, urea) is synthesised in the liver by ornithine cycle. In liver, one molecule of CO2 is activated by biotin and combines with two molecules of NH3 in the presence of carbamyl phosphate synthetase enzyme and 2ATP to form carbonyl phosphate reacts with ornithine and forms citrulline. Citrulline combines with another molecule of ammonia and forms arginine that is broken into urea and ornithine in the presence of an enzyme arginase and water. 
2 NH subscript 3 space plus CO subscript 2 space rightwards arrow with Arginase on top space NH subscript 2 space minus space CO minus space NH subscript 2 space plus straight H subscript 2 straight O
Urea is eliminated mostly through kidney as a nitrogenous excretory product.