Question

Which one of the following options gives the correct categorization of six animals according to the type of nitrogenous wastes (1, 2, 3) they give out?
A. Ammonotelic- Frogs, lizards
Ureotelic- Aquatic amphibia, humans
Uricotelic- Cockroach, pigeon
B. Ammonotelic- Aquatic amphibia
Ureotelic- Frog, humans
Uricotelic- Pigeon, lizards, cockroach
C. Ammonotelic- Aquatic amphibia
Ureotelic- Cockroach, humans
Uricotelic- Frog, pigeon, lizards
D. Ammonotelic- Pigeon, humans
Ureotelic- Aquatic amphibia, lizards
Uricotelic- Cockroach, frog

Answer 1

Hint: Body eliminates certain metabolic products after several metabolic processes as these products cannot be used by the body of that organism and maybe be even harmful if stored so they are better excreted out and some nitrogenous waste like urea, uric acid, ammonia are some of them.

Complete step by step answer: The excreted material is also based on the habitat and the nature of organisms as some excreted nitrogenous wastes are very toxic that need dilution and some are not that toxic.
-Ammonotelic organisms are the ones that excrete ammonia as their nitrogenous metabolic waste and ammonia is the most toxic nitrogenous waste and needs to be diluted in the surroundings when excreted. So, organisms like aquatic animals can excrete ammonia as it can then get diluted in the water. Protozoans, crustaceous, Platyhelminthes, cnidarians, poriferans, and echinoderms are other ammonotelic organisms.
-Ureotelic organisms are the ones that excrete urea as their metabolic nitrogenous waste and urea is the main excretory product in many organisms as urea is less toxic than ammonia and needs less water to dilute. Many bony and cartilaginous fishes along with humans and amphibians like a frog are ureotelic organisms.
-Uricotelic organisms are the ones that excrete uric acid as the metabolic waste and uric acid is least toxic among all other nitrogenous wastes and thus requires little water for its dilution so, lizards, snakes, cockroach, and birds are uricotelic organisms.
Hence, the correct answer is option (B).

Note: In the order of toxicity of the excreted nitrogenous metabolic waste ammonia is the highest and uric acid is the lowest, so ammonia needs to be diluted the most and uric acid the least.