Question

Which living organism is not a uricotelic?
A. Insects.
B. Birds
C. Crocodile
D. Alsatian dog

Answer 1

Hint:- All the various kinds of metabolic waste products are expelled out of the body in the form of water solutes and are mostly nitrogen in nature. There is a specialized organ system that works to remove the waste products from the body through different types of organs known as the excretory organs. The nitrogenous materials that are excreted as waste are ammonia, urea, uric acid etc.

Complete step-by-step solution:-
In the living organism several metabolic waste products are produced as a part of the natural process. These products are toxins that are produced due to different types of reactions such as cellular respiration. The products are harmful and toxic to the body and so have to be removed from the body as excrement. The excreted materials are mainly nitrogen compounds, water, phosphates and other substances such as carbon dioxide.
The nitrogenous wastes are waste products that contain excess nitrogen and are eliminated through excretory organs. They are produced during the breakdown of protein in the process of protein metabolism. They are mainly products such as ammonia, urea, uric acid and creatinine. THe main path of excretion of these wastes is urine and sometimes through the feces.
In certain organisms, the excretion of the metabolic wastes takes place in the form of ammonia and ammonium ions. Ammonia is produced through the oxidation of amino groups and is separated from protein during the conversion of carbohydrates. The excretion of ammonia from the body requires a lot of water to prevent toxicity by maintaining the level of body fluid. This type of excretion takes place in the aquatic organism.
The various land animals such as mammals and amphibians are known to excrete the nitrogenous waste in the form of urea. In these animals, the ammonia is converted into urea. The process of conversion of ammonia into urine takes place in the liver and kidneys. The resultant product urea is less toxic than ammonia and less water is required for its excretion. This form of excretion helps in conservation of water as compared to the excretion of ammonia. The animals that excrete urea are known as ureotelic.
In another form of excretion, the excess nitrogen is expelled in the form of uric acid. Uric acid is less toxic as compared to urea and ammonia and requires less energy in the production. During the excretion of uric acid, more water can be conserved as it is very low soluble in water. The uric acid is excreted in the form of concentrated white suspension and water is conserved. This type of excretion is found in the insects, reptiles such as crocodiles and lizards as well as birds.

Alsatian dogs belong to the Class Mammalia and so the excretion of nitrogenous waste through the body does not take place in the form of uric acid but instead form urea. Thus, it is not an uricotelic animal but is an ureotelic animal.
Therefore, the correct option is option D.

Note:- Nitrogenous waste products are naturally produced in the body through the metabolic process of protein and are toxin in nature. They are expelled by conversion of ammonia into uric acid in the mammals such as Alsatian dogs and they are known as ureotelic animals. In some other organisms, such as birds, insects and crocodiles, the excretion of uric acid takes place and they are known as uricotelic animals.