Question

In cockroaches, larval and nymphal characters are maintained by
A. Ecdysone
B. Salivary glands
C. Parotid gland
D. Juvenile hormone

Answer 1

Hint:A hormone analogue that prevents metamorphosis until the larval stage of cockroach has attained an appropriate phase of development. This hormone dominates in the larval stage of cockroaches.

Complete answerCockroach exhibits pauro metabolous development. Cockroach moults multiple times in their life cycle and shed a layer of skin out of their skeleton. It moults its hard-outer layer and it has to grow new layers periodically underneath the old layers. Nymphs undergo several stages of growth and the process of development is termed as moulting. They usually moult thirteen times in their life cycle, and after each moult, they appear more and more like adults. Wings are developed at the second last nymphal stage. Before the final moulting stage, wing pads develop. Nymph development to form an adult stage can take several months and years. Their development is dependent on the type of environmental conditions, types of cockroaches, and the prevalence of pathogenic organisms. After reaching its adult stage, it will not moult again. The young adult may look like a nymph, having wings that differentiate between a nymph and adult. The number of moultings can vary from one type of cockroach to another. This metamorphosis is controlled by the juvenile hormone that is produced by the corpora allata of the cockroach. It helps in the development of juvenile characters in the cockroach.
Hence, the correct option is D) Juvenile hormone.

Note: Moulting is also known as sloughing or ecdysis. It is a process by which cockroaches cast off a part of its body either at specific points in the life cycle.