Question

Which one is useful in metamorphosis of tadpoles into frogs?
A. Aldosterone
B. Thyroxine
C. Pituitary hormone
D. None of the above

Answer 1

Hint: Metamorphosis is a biological process in which an animal physically develops after the birth or hatching if it is an oviparous animal by successive series of changes . For example –metamorphosis of caterpillars to pupa and pupa to adult butterfly.

Complete Answer:
Metamorphosis of tadpole into frog: Metamorphosis of the tadpole into the frog is a process in which the tadpole (larval stage of frog) gets converted into the adult frog.
- Frogs are amphibians i.e they can live on land as well as in water.
- Frog’s tadpoles undergo through many stages to become an adult. During those stages they only remain in water.
- The hormone which is responsible for the metamorphosis of tadpoles into frogs is thyroxine which is secreted by the thyroid gland of frogs.
The stages are-
1. Egg
2. Tadpole
3. Young frog
4. Adult frog
1. Egg – The female frog lays a lot of fertilized eggs at one time in a pond or any standing water. The eggs float on the water surface in a jelly mass or cluster.

2. Tadpoles – The eggs hatch into the tadpoles. The tadpole looks like a fish. Tadpoles do not have legs, they have gills that allow them to breathe underwater. Tadpoles swim in the water and eat algae from the water.
- During this stage tadpoles start developing lungs to breathe outside the water as the frog is amphibian. Now the tadpoles start developing hind legs. Now it is starting to look like a frog instead of fish except its long tail.

3. Young frog – Now the tadpole grows two front legs and its tail becomes shorter and shorter. The tadpole used the nutrient stored in its tail as food. When its tail becomes short it becomes a young frog .

4. Adult frog – The young frog’s tail disappears completely and now it becomes an adult frog. It will now eat insects instead of algae from water. The adult frog has a stout body, protruding eyes, glandular skin. The adult frog can lay their eggs and begin their life cycle again.

Hence, option A is the correct answer for this question.

Note: Along with the thyroxine hormone, prolactin is also responsible for the metamorphosis of frogs. Frogs belong to the largely carnivorous group of amphibians.