Question

Where do the following functions occur in humans?
A. Production of egg
B. Fertilization
C. Implantation of zygote

Answer 1

Hint:- Human beings are viviparous and reproduce sexually. The events included in human reproduction are gametogenesis (production of gametes), transport of male gamete into the female reproductive organ (insemination), fusion of male gamete with the female gamete (fertilization) and finally formation of zygote that further develops into an embryo

Complete step-by-step solution:-
A. All the events of the reproduction in humans are performed at different times and places. It starts with the formation of gametes. The male gamete is known as sperm and the female gamete is called egg or ovum. Gametes are produced in the primary sex organs (testis and ovaries for males and females respectively). Ova or eggs are produced in the ovaries.
B. The male gametes are inserted into the female reproductive tract through copulation. The sperms are motile and thus travel towards the egg passing through cervix, uterus and finally arrive at the fallopian tube where they meet with the egg at the junction of isthmus and ampulla of the fallopian tube, known as ampullary-isthmic junction. When a sperm fuses with an egg, the process is termed as fertilisation.
C. When two haploid gametes i.e. the sperm and egg are fused, a diploid zygote is formed. The zygote undergoes several mitotic divisions and forms a blastocyst. The blastocyst is implanted into the uterus through a layer called trophoblast. This process is known as implantation.

Note:- Whether the sperm that fused with the egg has X or Y chromosome, determines the sex of the embryo. The egg always has an X chromosome. If sperm having X chromosome fuses with the egg, the sex of the embryo would be female (XX), and if a sperm having Y chromosome fuses with the egg, it produces a male (XY).