Question

Which is uricotelic: Earthworm, Cockroach, Frog or Human?

Answer 1

Hint: All animals excrete metabolic wastes from their body. Metabolic wastes are substances that are left after metabolic activities. These metabolic wastes are of no use to the organisms and sometimes can be toxic. Hence, they must be excreted out of the body to maintain homeostasis.

Complete explanation:
The metabolic wastes include nitrogenous wastes, \[C{O_2}\], fecal matter, water etc. The excess nitrogen from the body must be excreted and such waste compounds are called nitrogenous wastes. It includes ammonia, urea, guanine, and uric acid. Organisms that excrete nitrogen in the form of ammonia are termed as ammonotelic. Organisms that excrete nitrogen in the form of uric acid are called Uricotelic. Organisms that excrete nitrogen in the form of urea are known as ureotelic. Organisms that excrete nitrogen in the form of guanine are called purinotelic.
Earthworms excrete nitrogen in the form of ammonia gas. Hence, they are ammonotelic organisms.
Cockroaches- are not found in regions that contain high levels of water. They excrete in the form of uric acid, which is somewhat solid. Cockroaches are uricotelic organisms.

Frogs- Frogs are ureotelic organisms. The nitrogenous waste excreted by them is urea.

Human- human beings excrete nitrogen in the form of urea. Hence, they are ureotelic organisms.

Note:
The type of nitrogenous wastes that are excreted by a living organism is determined by the availability of water in an environment and solubility of the nitrogenous wastes in water. For instance, ammonia is easily soluble in water. Whereas, uric acid is less soluble in water when compared to urea.