Question

Fertilisation membrane is formed to

• A. Provide stability to egg
  
• B. Prevent polyspermy
• C. Facilitate entry of sperm into egg
  
• D. Prevent monospermy
  

Answer 1

The correct option is B Prevent polyspermy

Fertilisation membrane
Fertilisation membrane is a membrane formed on the inner surface of the vitelline membrane of the ovum after the entry of a spermatozoon to prevent the entry of additional sperms.

Formation of Fertilisation membrane
Cortical granules present below the plasma membrane fuse with the latter and release their enzymatic contents between the plasma membrane and the zona pellucida. These enzymes harden the zona pellucida which helps in the prevention of the entry of additional sperms into the secondary oocyte. Thus prevents polyspermy.

Acrosome
Acrosome present on the anterior side of the sperm is derived from the Golgi bodies which contain enzymes that facilitate the entry of sperm into the ovum.

Monospermy
Monospermy is the entry of a single sperm into an egg for fertilisation.

Polyspermy
The penetration of a secondary oocyte by more than one sperm is called polyspermy.

Final answer
(D) Prevent polyspermy