Question

Nematodes enter the stage of ‘lethargus’ during:

• A. Quiescence
• B. Killing and fixing
• C. Molting
• D. Desiccation

Hint:

Lethargus is a sleep-like or quiescent phase nematodes enter prior to developmental transitions.

Answer 1

The Correct Option is A

Lethargus is a temporary inactive stage during which nematodes stop feeding and become quiescent. It occurs as part of their developmental cycle, commonly interpreted as a quiescent phase.

Answer 2

Lethargus can be understood by looking at what happens around it rather than just naming it. It is not the act of molting itself (option molting) but the resting period that precedes each moult, when the nematode retracts from the old cuticle and stops feeding and moving. 'Killing and fixing' is a laboratory preparation technique, not a natural developmental stage, and 'desiccation' refers to water loss under adverse conditions (anhydrobiosis), a different survival mechanism altogether. By elimination, lethargus is best described as a quiescent, inactive phase of the moult cycle.