Correct option is C
The acrosomal reaction is a crucial event in the process of fertilization, specifically when the sperm comes into contact with the zona pellucida, which is a glycoprotein layer surrounding the egg. Option (c) is the correct answer because the primary function of the acrosomal reaction is to digest the zona pellucida. Here's how it works:
Acrosomal Vesicle Activation: The acrosome is a membrane-bound vesicle in the head of the sperm that contains enzymes such as hyaluronidase, acrosin, and other digestive enzymes.
Sperm-Egg Interaction: When the sperm reaches the egg, it binds to the zona pellucida, which is a tough, glycoprotein layer surrounding the egg.
Acrosomal Reaction: In response to this binding, the acrosome undergoes a reaction where its membrane fuses with the sperm's plasma membrane. This fusion releases the acrosomal enzymes into the surrounding area.
Zona Pellucida Digestion: The released enzymes, particularly hyaluronidase and acrosin, break down the components of the zona pellucida, allowing the sperm to penetrate through it. This enables the sperm to reach the egg's plasma membrane and complete the fertilization process.
Incorrect Options:
Option (a) Repulsive interaction between sperm and egg: Incorrect — There is no repulsion; in fact, the sperm must have an affinity for the egg's zona pellucida for the acrosomal reaction to occur.
Option (b) Involves digestion of the acrosome by the sperm: Incorrect — The acrosome does not digest itself. Instead, it releases enzymes to digest the zona pellucida.
Option (d) Fusion of the sperm and egg plasma membranes: Incorrect — This happens after the acrosomal reaction, once the sperm has penetrated the zona pellucida.
