Q. Grey crescent is the area :
A) at the point of entry of sperm into ovum
B) just opposite to the site of entry of sperm into ovum
C) at the animal pole
D) at the vegetal pole
Explanation
[Solution from source] In a frog egg, sperm entry makes the pigmented cortex rotate, which exposes a lighter grey band on the side opposite the entry point. This grey crescent later marks the dorsal side of the embryo (dorsal lip of the blastopore). It is not at the entry site itself or at either pole. Answer (2).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.