Question

Which substance is finally excreted in the urine?

• A. Amino acid
• B. Urea
• C. Glucose and glycogen
• D. Uric acid

Answer 1

Answer: (B)

The urea cycle converts two amino groups, one from ammonium ion and one from aspartate, and a carbon atom from bicarbonate, to the relatively nontoxic excretion product urea. Ornithine is the carrier of these carbon and nitrogen atoms. Glucose is completely reabsorbed by the capillaries. Thus, urea is finally the main product of urine.

So, the correct answer is option B.