Question

Excretion of nitrogenous wastes mainly as uric acid by birds is helpful for

• A. Conserving body water
• B. Eliminating excess body water
• C. Eliminating excess body heat
• D. Conserving body heat

Answer 1

The correct option is A Conserving body water

Uric acid is excreted by the animals which conserve water, at least during parts of their life cycle, such as birds, terrestrial reptiles, insects and some snails. In this case ammonia is converted into uric acid because it is less toxic than ammonia but it is insoluble in water. Uric acid is excreted in crystalline form mixed with, but not dissolved in, small amounts of water. In fowls (chickens and turkeys), blood level of uric acid is about 5 mg/100 ml, while insects have as much as 20 mg uric acid/100 ml of blood. Thus, option A is correct.