Question

In living beings, ammonia is converted into urea through

(a) ornithine cycle

(b) citrulline cycle

(c) fumarine cycle

(d) arginine cycle

Answer 1

Correct Option (a) ornithine cycle

Explanation:

Ornithine combines with one molecule of NH₃ and CO₂ to produce citrulline. Citrulline combines with another molecule of NH₃ to form arginine. Arginine is broken down into urea and ornithine which repeats the cycle. This is called Ornithine cycle or urea cycle or Krebs-Henseleit cycle.