Question

Birds, insects, and many reptiles excrete nitrogenous waste in the form of uric acid, which _____. see concept 44.2 (page 980)

Answer 1

The answer would be:
reduces water loss compared to other nitrogenous wastes, but requires more metabolic energy to produce

Nitrogen waste needs to be removed out of the body. There are a few ways to remove the nitrogen waste but it will vary in the amount of energy used. 
Uric acid is less soluble which makes it won't be secreted in urine, thus reducing the need to urinate and reduce water loss. But the production of uric acid need hydrolysis of ATP, so it needs more energy.
Fish will secrete the waste as ammonia which soluble in water but doesn't need ATP to synthesize.