In the caterpillar, molting and metamorphosis are under the control of the same hormone. What is the hormone? How are these separate developmental pathways controlled by the same hormone?

The correct answer will be - 20-hydroxyecdysone

Explanation:

Ecdysone is a steroid hormone produced in the Arthropods which plays an important role in coordinating and regulating the different developmental transitions like larval moulting and the metamorphosis.

The other effector hormone also plays an important role in molting and metamorphosis called Juvenile hormone.

The presence of juvenile hormone prevents the ecdysone induce changes which regulate molting and gene expression during metamorphosis.

Therefore the presence of the juvenile hormone leads to the different stages of molting while the absence of juvenile hormone promotes the development of metamorphic stages like the development of pupa.

Thus, 20-hydroxyecdysone is the correct answer.