Moderate

In the urea cycle, one molecule of ammonia and one molecule of CO2 combine with one molecule of ornithine to form:

Correct answer: D. Citrulline

  • A. Urea
  • B. Arginine
  • C. Arginosuccinate
  • D. Citrulline

Explanation

Citrulline is an amino acid involved in the urea cycle, where it is converted into arginosuccinate. It is also a precursor to arginine, playing a role in protein synthesis and the production of nitric oxide, which helps regulate blood vessel function.

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About Homeostasis

Homeostasis maintains a stable internal environment through the kidney and urinary system, thermoregulation and excretion. The kidney topics include filtration, selective reabsorption, urine formation and water balance, while thermoregulation involves sweating, vasodilation, vasoconstriction and hormonal control; excretion is different from egestion, which removes undigested food.

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