Question

Zygote is formed by
A. Fusion of two cell
B. Fusion of gametes
C. Fusion of only chloroplast portion of gametes
D. Fusion of polar cell

Answer 1

Hint: Zygote is a fertilised egg and it is a diploid cell as it contains genetic materials from both the father and the mother. The zygote further developed into the embryo which is the early stage of development of humans.

Complete answer:
The fusion of male gamete sperm and the female gamete ovum is known as fertilization. The fertilisation takes place at the ampulla which is the isthmic junction of the fallopian tube. As a result of fertilisation, the fertilized ovum is transferred into a single-cell zygote. The zygote by repeated mitotic division produces many cells which in times differentiated into different tissues and organs of the developing embryo. These repeated cell divisions of the zygote for the development of the embryo is known as embryogenesis. The cleavage starts at the beginning of embryological development. The process of cleavage is completed during the passage of the fertilized ovum through the fallopian tube to the uterus.
The genome of gamers is a combination of the DNA in each gamete and it contains all of the genetic information which is essential to form a new individual. In multicellular organisms, the zygote is the earliest developmental stage. In the case of human fertilization, a fertilized ovum and a haploid sperm cell fused to form a single 2n diploid cell called the zygote.
Hence, the correct answer is ‘B. Fusion of gametes’.

Note: The human male produces about 300-400 million sperm per ejaculation and the process of deposition of sperm in the female genital tracts is known as insemination. When the embryo reaches the stage of 16-32 called structure, it is known as the morula.