Question

The graph shows the enzymatic activity needed for excretion of urea. The graph depicts mode of excretion of frog which has changed from ............. to ........ in adult.

• A. Uricotelism, ammonotelism
• B. Ammonotelism, ureotelism
• C. Ureotelism, ammonotelism
• D. Ureotelism, uricotelism

Answer 1

Answer: (B)

In aquatic animals ammonia is the main nitrogenous waste; and only about 10% of nitrogenous wastes are excreted as urea. Most amphibians are at least semi aquatic, and their mechanisms of osmoregulation are similar to those of freshwater fishes. They, too, produce large amounts of dilute urine. In its urine and through its skin, a frog can lose an amount of water equivalent to one third of its body weight in one day. Active transport of salt inward by special cells in the skin compensates for loss of salt through skin and in urine. In larval stage or tadpole stage frog excretes ammonia ie it is ammonotelic animal but a adult frog is terrestrial and changes to ureotelism ie excretes urea.