Question

Grooves with a purely functional origin in insects is called:

• A. Sulci
• B. Membrane
• C. Pit
• D. Crack

Hint:

“Crack” in entomological terms refers to a functional rather than developmental groove on the insect exoskeleton.

Answer 1

The Correct Option is D

In insect morphology, a crack or functional groove may appear as a break or fault in the exoskeleton structure, often forming functionally (not embryologically) to allow specific flexion or segmentation.

Answer 2

Definition-based elimination:
A Sulcus is a true, embryologically determined groove that usually marks an internal ridge (apodeme) in the insect exoskeleton, so it is ruled out here since the question asks for a purely functional (non-developmental) groove.
A Membrane is a flexible connecting area, not a groove, and a Pit is a small depression rather than a linear groove, so both are eliminated on definition.
What remains is a Crack, a secondary, functionally formed line that appears without following the true embryonic suture pattern of a sulcus.