Question

In man, the urea is mainly produced in
A. Liver
B. Kidneys
C. Gallbladder
D. Spleen

Answer 1

In feed supplements, urea is utilised as a source of non-protein nitrogen (NPN). If more urea is ingested than the rumen microbes can metabolise it, the ammonia is taken into the bloodstream. In the liver, ammonia is converted to urea, which is then expelled by the kidneys.

Complete answer:
Urea is produced by the urea cycle or ornithine cycle in the liver. It converts 2 ammonium ions and one carbon atom into urea. Arginine acts as a carrier of ammonium and carbon atoms.

So we can say that the correct answer is option A. Liver

The urea cycle, also known as the ornithine cycle, in the liver produces urea. It produces urea by converting two ammonium ions and one carbon atom. Urea forms when dietary proteins make amino acids after digestion. The liver breaks down excess amino acids to make ammonia, then converts this into urea, which is less toxic in the body than ammonia.
Urea travels through the bloodstream to the kidneys, where it is excreted in urine together with water and other impurities. The rate of urea production is controlled by the protein content of the food, as one might assume; a low-protein diet is linked to lower urea production, whereas a high-protein diet is linked to higher urea production.
Urea is a key component of mammalian urine. As a result, it's understandable that some people wonder if the urea in cosmetics comes from urine. Urea is synthesised in a lab and used in commercial cosmetics. Synthetic urea is also often used to aid fermentation in baked goods and wines.

Note:-
Amino acids, urea, uric acid, carbon dioxide, water, and ammonia are among the excretory products. Amino acids are excreted by some Molluscs and Echinoderms as waste products from the body. Ammonia is the principal excretory product in mammals, and it is made up of proteins found in our meals.