Question

Are animals requiring the minimum amount of water to produce urine?
A. Ureotelic
B. Ammonotelic
C. Uricotelic
D. Chemotelic

Answer 1

Hint: Excretion can be defined as the process of expelling non-gaseous nitrogenous waste like ammonia, urea, uric acid, and etc. along with excess water, salts and pigments out of the body. The main aim of excretion is to keep a constant internal chemical composition called homeostasis.

Complete answer:
The three modes of excretion seen in animals, based on the nature of nitrogenous end products are:
Ammonotelism- It is the type of excretion in which the main nitrogenous waste is ammonia and ammonium ions. The animals with ammonotelism are called ammonotelic animals.
It is found in many aquatic animal groups like protozoans, sponges, aquatic insects, echinoderms, and some adult aquatic amphibians like salamanders.
Ammonia is highly toxic because it has high pH so it must either be metabolized or expelled out of the body so that its concentration remains low in the blood. It is highly soluble in water so a large amount of water is required to expel it out of the body.
Ureotelism
It is a type of excretion in which main nitrogenous waste is urea and animals showing ureotelism are called ureotelic animals.
It is found in those land animals which can lose large amounts of water without any ill-effect and that can retain considerable amounts of urea as major osmolyte to maintain osmolarity of their blood. It is a common method of excretion in man and all other mammals.
Uricotelism
It is the type of excretion in which the main nitrogenous end product is uric acid. The animals showing uricotelism are called uricotelic animals. It is a common method of excretion in birds, snakes, land reptiles, land snails, etc.

So, the correct answer is option (C).  

Note: Uricotelism is the least soluble nitrogenous waste and requires very less water for its elimination. So excretion of uric acid is a greater advantage to land animals as they have limited access to water. It is a great adaptation for the terrestrial mode of life.