The joining of a sperm and an egg during sexual reproduction is called fertilization.

Explanation:

Fertilization is a crucial step in sexual reproduction. It is the process by which a sperm cell from a male combines with an egg cell from a female to form a new individual. This process can occur in plants as well as animals.

Process of Fertilization:

1. Sexual Reproduction: Sexual reproduction involves the fusion of male and female gametes (reproductive cells) to create offspring. In animals, the male gamete is the sperm cell, while the female gamete is the egg cell. In plants, the male gamete is contained in pollen, and the female gamete is present in the ovule.

2. Transfer of Gametes: In animals, the male deposits sperm into the female reproductive system during sexual intercourse. In plants, pollen is transferred from the male reproductive organ (stamen) to the female reproductive organ (pistil) through various means like wind, insects, or other animals.

3. Fusion of Sperm and Egg: Once the sperm reaches the egg, it penetrates the egg's protective layers and fuses with its nucleus. This fusion combines the genetic material from both parents, resulting in a zygote.

4. Zygote Formation: The zygote is the first cell of the new individual. It contains the complete set of chromosomes, half from the mother and half from the father. The zygote divides and develops into an embryo, which eventually grows into a new organism.

Significance of Fertilization:

Fertilization is essential for the continuation of a species. It ensures genetic diversity by combining the genetic material from two parents, resulting in offspring with unique characteristics. Fertilization also allows for the transfer of genetic traits and adaptations, which contribute to the survival and evolution of a species.

In conclusion, fertilization is the process of joining a sperm and an egg during sexual reproduction. It is a vital step in the creation of new individuals and plays a crucial role in genetic diversity and the continuation of species.

Fertilization