Question

Which of the following hormone control metamorphosis in a frog?
A.Adrenalin
B.Insulin
C.Oxytocin
D.Thyroxine

Answer 1

Hint: Metamorphosis occurs in amphibians and the transformation of larva to miniature adult replicate and usually form an aquatic to terrestrial or semi terrestrial system.
The endocrine system consists of isolated endocrine glands or ductless glands that discharge their secretions called hormones into the blood.

Complete step by step answer:
-The hormones act as chemical messengers which control and coordinate the functioning of the various organs of the body.
-The endocrine glands of frog include pituitary,pineal ,thyroid , parathyroid , thymus , adernals, pancreas and gonads
-Metamorphosis is initiated internally and maintained by hormone thyroxine and the process is obligatory
-Thyroxine exhibits extensive cellular ,biochemical and morphological changes to occur during metamorphosis.
-Events that occur during altered gene expression, morphogenesis , tissue restructuring and extensive cell death.

So the correct answer is D. Thyroxine

Additional information:
-It inhabits fresh water and moist land. Rana tigrina is an amphibian as it live in water as well as on land
-Frogs breed in the rainy season i.e. from July to September. They seek shallow quiet water for this purpose.
-In case of frogs there is no parental care.
-The fertilized egg undergoes holoblastic cleavage and produces a small larva called tadpole .
-The tadpole resembles fish in form and mode of life. It respires through gills, swims with tails and is fully aquatic.
-The tadpole grows and metamorphoses into a small frog.

Note:
The thyroxine hormone released from the thyroid brings the developmental change in frog. As it regulates the metabolism of an organism.