Question

If a trace of thyroid extract is put to water containing tadpoles, it will

• A. Slow down the metamorphosis
• B. Hasten the metamorphosis
• C. Keep them as tadpoles
• D. Kill the tadpoles

Answer 1

Answer: (B)

Hasten the metamorphosis

Metamorphosis is a biological process by which an animal physically develops after birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some insects, fishes, amphibians, molluscs, crustaceans, cnidarians, echinoderms and tunicates undergo metamorphosis, which is usually accompanied by a change of habitat or behavior.

If a trace of thyroid extract is put to water containing tadpoles, it will hasten the metamorphosis. Thyroid hormones are essential for metamorphosis.

Metamorphosis in amphibians is regulated by thyroxine concentration in the blood, which stimulates metamorphosis, and prolactin, which counteracts its effect.

So, the correct answer is option B.