Question

The conversion of protein waste, the ammonia into urea occurs mainly in:

• A. kidney
• B. lungs
• C. liver
• D. intestine

Answer 1

The correct option is C

liver

The correct option is C.

Explanation for the correct option :

1. Urea is formed in the liver by a cyclic process called as the urea cycle or ornithine cycle.
2. The amino acids that are not needed in the body are deaminated by an enzyme oxidase, producing ammonia NH₃.
3. Ammonia is toxic and quickly changes into urea.
4. The urea is then eliminated through urine.

Explanation for incorrect option :

Option A:

1. Most of the urea produced by the liver is excreted by the kidneys.
2. Excretion of a large fraction of the urea filtered by the glomerulus.

Option B:

Lungs help in the excretion of carbon dioxide which is formed as a result of cellular respiration.

Option D:

The intestine helps in the absorption of nutrients and water from the digested food.

Final Answer: The conversion of protein waste, the ammonia into urea occurs mainly in the liver.