Question

Which of the following is incorrect about fertilization?
A. It restores diploid condition.
B. It activates the egg.
C. There is no variation.
D. It determines the sex of offspring.

Answer 1

Fertilization is a key step in the process of sexual reproduction. It involves the fusion of the male gamete with the female gamete inside or outside the body of females. Both the gametes carry half a genome that fuses to form a complete genome in a zygote.

Complete answer: Fertilization is defined as the process of union of a male and female gamete that is haploid to form a diploid zygote. Haploid means cells that have half the number of chromosomes than in a normal cell. Diploid means cells having a full set of chromosomes. To retain the diploid state the haploid gametes fuse. The process initiates at the moment the male gamete enters the female body and swims towards the female gamete. The male gamete is small and motile termed as sperm and the female gamete is big and static termed as an egg. As soon as the sperm reaches the egg it activates it to undergo the process of meiotic division and complete its second meiotic cycle that makes the egg functional to be turned into a zygote. Activation of an egg is important as it stimulates the egg to form important proteins and enzymes required for future zygote.

After activation of the egg, the sperm enters its nucleus inside the egg. This completes the diploid state of the egg. Now, this stage is called the zygote stage. The zygote multiplies rapidly by mitotic division. The initial divisions result in recombination as the gametes are from two different parents and they cross-over to result in variations. Also, the male gametes carry the information that decides the sex of the baby. The female gamete always carries a pair of X sex chromosomes. The male carries one X and one Y chromosomes as its sex chromosomes. If the Y carrying sperm fuses with the egg, it results in male offspring and vice versa.
Therefore, the right answer is option C.
Note: The process of fertilization is the initial step involved in reproduction. After this crucial step, the mother becomes pregnant and the growth of the zygote takes place. The zygote undergoes various divisions and then becomes a fetus. This fetus becomes a complete baby at the end of 9 months of gestation.