Question

Which one is uricotelic?
A. Frogs and toads
B. Lizards and birds
C. Cattle, monkey and man
D. Molluscs

Answer 1

Hint: Different organisms have different methods of removing body wastes and the wastes are removed in different forms like ammonia (Ammonotelic), urea (Ureotelic), uric acid (Uricotelic), and amino acids (Aminotelic).

Complete answer:
Uricotelic organisms remove their body waste in the form of uric acid. Uric acid and other nitrogenous wastes are removed as a result of deamination which is the process of removal of amino groups from the amino acids that make up proteins. These amino groups after removal are converted into urea, uric acid, ammonia on the basis of physiology of organisms and the availability of water in their body. The portion of amino acid left after the removal of the amino group is oxidised to produce energy or is stored as reserve food.

Organisms that are found in dry areas with scarcity of water like in the deserts, where their bodies need to conserve water are uricotelic. Lizards, reptiles, birds, and kangaroo rats are uricotelic.

Hence, the correct answer is option (B).

Additional information:
• Humans also release minute quantities of uric acids by the breakdown of purines and pyrimidines which are nitrogenous bases present in nucleic acids.
• Human beings are ureotelic means they release urea as excretory waste.
• Ammonia is the most toxic nitrogenous waste which is released by molluscs and echinoderms.
• Guano – Excretory waste of birds that is rich in uric acid crystals, it is used as fertilizer.

Note: Uric acid is released by animals which are found in deserts because uric acid is insoluble in water and does not require water for its removal like urea which is formed from ammonia mostly in the liver and to an extent in the kidneys.