Question

Addition of a trace of thyroxine or iodine in water containing tadpoles will

• A. Keep them in larval stage
• B. Hasten their metamorphosis
• C. Slow down their metamorphosis
• D. Kill the tadpoles

Answer 1

Answer: (B)

Hasten their metamorphosis

In frogs, growth and metamorphosis (development of frog from tadpole stage to adult stage) is regulated by thyroxine gland. Thyroxine is secreted from thyroid gland. It stimulates the consumption of oxygen by metabolically active tissues and also increases the oxidation of glucose in tissues. Hence, addition of a trace of thyroxine or iodine in water containing tadpoles will hasten or speed up their metamorphosis.

So, the correct answer is 'Hasten their metamorphosis'.