Question

With respect to the assertion (A) and reason (R), which of the following is correct option?

A: A tadpole deprived of thyroid gland fails to metamorphose into an adult.

R: Thyroxine stimulates tissue differentiation and, therefore, affects metamorphosis of a tadpole into an adult frog.

• A. If both A and R are true and R is the correct explanation of A.
• B. If both A and R are true but R is not correct explanation of A.
• C. If A is false but R is true.
• D. If both A and R are false

Answer 1

The correct option is A

If both A and R are true and R is the correct explanation of A.

Metamorphism is a hormonal effect. Metamorphism in frogs is controlled by the hormone called thyroxine. The hormone produced by the gland called thyroid. For the production of thyroxine, thyroid gland needs iodine. Frogs need to live in water bodies where sufficient iodine is present for thyroxine production. Hence, deficiency of iodine can retard the growth of a larva to become an adult frog.