Question

Define fertilization. give difference between its two types. class 10

Answer 1

Fertilisation is the fusion of male and female gametes to give rise to a single cell – zygote. Fertilisation can be external fertilisation or internal fertilisation.

*When male and female gametes unite outside the body, it is called external fertilisation
*When fertilisation takes place inside the body, it is called internal fertilisation.
*When fertilisation takes place in a test tube, the offspring are called test tube babies.
*Fertilisation that takes place outside the human body is in-vitro fertilisation.

Internal fertilisation takes place in the body of a female who delivers the baby on completion of the gestation period.

External fertilisation takes place in frog. During rainy season as female frog lays eggs entangled in jelly like substance on the surface of water. Immediately, male frog deposits sperms over the eggs. Sperms move with the help of their tail and randomly fertilise the eggs.

In-vitro fertilisation can be explained in case of test tube babies. Freshly ovulated eggs are collected from women who are incapable of bearing babies. These eggs are maintained under sterilized conditions and are fertilised with the semen collected from the husband of the woman. As the zygote is formed, it develops for seven days under controlled lab conditions. At this stage, embryo is transferred into the uterus of surrogate mother. Foetus develops in the mother’s womb and is delivered at the end of nine months.

Zygote, the super cell marks the beginning of a new individual. The zygote divides repeatedly to form a ball of cells making an embryo.