Question

Two examples in which the nitrogenous wastes are excreted from body in the form of uric acid are
a. Birds and lizard
b. Mammals and molluscs
c. Insects and bony fishes
d. Frogs and cartilaginous fishes

Answer 1

Hint: Nitrogenous waste is excreted from the body in the form of uric acid. The nitrogenous waste that is generated in the body tends to produce toxic ammonia if remained in the body it must be excreted.

Complete answer:
So many animals excrete nitrogenous waste in the form of uric acid among many other forms and they produce uric acid in order to conserve the water present in the body which helps them in their survival.

Lizards, birds, land snails and insects excrete nitrogenous wastes as uric acid in the form of paste with very less water loss and are termed as uricotelic animals.

The birds and the reptiles turn the nitrogenous waste into uric acid. They have a chamber called cloaca in which digestive wastes, uric acid, and eggs or sperm go before leaving the body. Birds can absorb some of the water back into the system while the uric acid is in the cloaca.

Hence, the correct answer is option (A).

Note: The least toxic metabolic product of protein metabolism is the uric acid which is excreted by urine. The small molecular size and high solubility of ammonia in water readily diffuse to the aquatic environment at gill or skin surface. Urea is the nitrogenous waste which can be excreted in the form of saliva. Urea is the final product that is broken down in the amino acid breakdown of the body. Nitrogenous waste products are formed due to deamination of unwanted amino acids.