Multiple choice In ornithine cycle, which of the following wastes are removed from the blood? CO2 and ammonia Ammonia and urea CO2 and urea Urea and urine Reveal answer Fill a bubble to check yourself A Correct answer Explanation In ornithine cycle, CO2 and ammonia wastes are removed from the blood. In mammals, this cycle takes place primarily in the liver, and to a lesser extent in the kidney.