Question

The most important significance of fertilizin and antifertilizin reaction is to
(a) Preserve the sperm.
(b) Ensure that at least few spermatozoa encounter the egg.
(c) Mutually attract the gametes of opposite sexes.
(d) Ensure fusion of gametes of the same species.

Answer 1

When sperm reaches the ovum within the oviduct it releases a substance referred to as antifertilizin. It is composed of protein secreted by the acrosome. At an equivalent time, the ovum releases another chemical substance referred to as the fertilizin.

Complete answer:
When egg and sperm fuse together, fertilization takes place, and leads to the formation of zygote. Mature egg secretes a chemical known as fertilizin, which is composed of glycoprotein present in the cortical region of the egg cytoplasm. Sperm secretes a chemical known as antifertilizin, which is composed of a protein (composed of acidic amino acids) present in the plasma membrane of the sperm. Fertilizin acts as a receptor for the antifertilizin and the reaction between fertilizin and antifertilizin makes the sperm stick to the egg surface and make it more capable of fertilizing the egg of the same species.
The tail and the outer coating of the sperm disintegrate after the sperm enters into the cytoplasm of the oocyte, cortical reaction occurs which prevents other sperm from fertilizing the same egg.
The oocyte now undergoes its second meiotic division which produces the haploid ovum and releases a polar body. The nucleus of sperm then fuses with the ovum, enabling the fusion of their genetic material.
So, the correct answer is ‘Ensure fusion of gamete of the same species’.

Note: The fertilizin and antifertilizin reaction normally takes place in the ampulla of the fallopian tube (site of fertilization) when the sperm penetrates the secondary oocyte. Several disorders can emerge from defects in the fertilization process.