Question

In the kidney, nephrostomes are functional in
A.Tadpole
B.Adult frog
C.Cockroach
D.Rabbit

Answer 1

Waste products are formed after metabolic activities in living organisms. Metabolic waste is removed from the body by various means. Some animals have well developed excretory system while others have simple excretory organs.

Complete step by step answer: Nitrogenous wastes are formed after amino acid and nucleic acid metabolism. The type of waste materials formed and the method of elimination from the body is different in organisms. It greatly depends upon the metabolic activities inside the body and the environment in which an organism lives. Know that the basic form of excretory material of nitrogenous waste is ammonia. It is excreted in several forms like uric acid or urea in organisms. Based on this, we can classify excretion as ammonotelism, ureotelism, and uricotelism.
We know that the mode of excretion amphibians is different according to their life stages. In the tadpole stage, waste is excreted as ammonia and in the adult stage, they are ureotelics.
In the tadpole stage, excretion is done with the help of specialized structures called nephrostomes. These are conical structures that possess cilia that help in driving water into the kidney or metanephridia.
In the adult stage, nephrostomes are non-functional in nature. The main organs of excretion are kidneys that are composed of several uriniferous tubules or nephrons. Adult frog excretes urea which is carried by blood into the kidneys.
Hence the correct option is B.

Note: Know that unlike humans, frogs have a specialized structure called cloaca in their excretory system. A common ureter opens to the cloaca. Know that a thin urinary bladder is also present in the ventral side also opens to the cloaca.