Urea Formation in the Liver from Amino Acids

Steps:

• Amino acids are deaminated, releasing ammonia as a toxic byproduct.
• The liver's urea cycle converts ammonia into non-toxic urea.
• Urea is then transported to the kidneys for excretion in urine.
• Carbohydrates provide energy but do not contribute to urea synthesis.

Why B is correct:

• The urea cycle, discovered by Hans Krebs, occurs exclusively in liver hepatocytes to detoxify ammonia from amino acid catabolism.

Why the others are wrong:

• A: Kidneys filter and excrete urea but do not synthesize it.
• C: Carbohydrates are broken down for glucose, unrelated to nitrogen waste like urea.
• D: Liver processes carbohydrates for energy, not urea formation.

Final answer: B