AP BIOLOGY

Detailed explanation-1: -Nitrogenous wastes in the body tend to form toxic ammonia, which must be excreted. Mammals such as humans excrete urea, while birds, reptiles, and some terrestrial invertebrates produce uric acid as waste. Uricothelic organisms tend to excrete uric acid waste in the form of a white paste or powder.

Detailed explanation-2: -Mammals, including humans, are the primary producers of urea. Because they secrete urea as the primary nitrogenous waste product, they are called ureotelic animals. Urea serves an important role in the metabolism of nitrogen-containing compounds by animals.

Detailed explanation-3: -Solution : Ans: Mammals excrete urea because they do not possess sufficient water available for speedy elimination of ammonia. The elimination of urea requires less water and mammals can afford to concentrate urea in the urine more than the blood.

Detailed explanation-4: -Urea is a less toxic compound compared to ammonia. They eliminate two nitrogen atoms and for its excretion, less water is required.

Detailed explanation-5: -Mammals, many terrestrial amphibians and marine fishes mainly excrete urea and are called ureotelic animals. Ammonia produced by metabolism is converted into urea in the liver of these animals and released into the blood, which is filtered and excreted out by the kidneys.