Which organ primarily carries out the urea cycle?

• A. Liver
• B. Kidney
• C. Pancreas
• D. Small intestine

Answer: (A)

The urea cycle detoxifies ammonia by turning it into urea for safe elimination, and this process happens mainly in the liver. The liver’s hepatocytes carry out the enzymatic steps of the cycle, starting with the mitochondrial reaction and continuing in the cytosol, so it is the primary site for making urea. The kidney’s role is to excrete the produced urea and regulate fluid balance, not to run the cycle itself. The pancreas and small intestine are involved in digestion and nutrient processing, not in converting ammonia to urea.