Question

The excretory product of fresh water fishes is-
A. Urea
B. Uric acid
C. Ammonia
D. Guanine

Answer 1

Hint: The water intake capacity of freshwater fishes is very little and thus the excretory product amount in the form of liquid is very little. The excretory product in the form of ammonia requires the simplest process and needs to be in contact with water frequently. So fishes can continuously excrete this harmful product.

Complete answer-
Option A Urea- This is the excretory product of mammals. It requires the most complex mechanism to convert ammonia to urea. A lot of water is excreted out. Animals excreting urea are called ureotelic organisms.
Option A is not the correct answer.
Option B Uric acid- This is not fully soluble in water. This is the excretory product of aves. Uricotelic organism’s organism tend to excrete uric acid in the form of white paste.
Option B is not the correct answer.
Option C Ammonia- This is easily soluble in water. Thus, the fresh water fishes utilize it as their excretory product.
Hence option C is the correct answer.
Option D Guanine-This is totally insoluble in water. This is the excretory product of living organisms having scarcity conditions of water. Too little water is conserved. Most animals living in deserts have this as their excretory product.
Option D is not the correct answer.

Hence option C is the correct answer.

Note:
Ammonia is very toxic for living organisms so it needs to be excreted out immediately. As fishes live in aquatic environments it is easier for them to excrete it out. This needs less consumption of water as fresh water fishes consume less water to maintain their body weight balance inside water. In human health ammonia ions are produced naturally and are components of metabolic processes.