Question

Differentiate between external and internal fertilization.

Answer 1

Hint: Fertilization is a process by which male and female gametes undergo fusion to form a zygote. Depending upon the location of fertilization and embryo development, it can be of different types.

Complete answer:

S.No.	Internal fertilisation	External fertilisation
1	The egg and the sperm (gametes) will undergo fusion inside the female’s body.	The fusion of male and female gametes occurs outside the female body, in an external environment.
2	The male gamete is released inside a female’s genital tract.	When males and females meet, the female organism lays the eggs, and the male releases sperm. When the eggs and sperms meet, then they fuse and undergo fertilization.
3	Fertilization and embryo development occur inside the female body.	Fertilization as well as embryo development occurs outside the female body.
4	The survival chance of the zygote is higher as the offspring will properly be nurtured by the parents.	The survival chance of the offsprings is low because the gametes are usually attacked by the predators.
5	Fertilization can occur either in the aqueous environment or it can occur in the terrestrial bodies.	Fertilization majorly occurs in the aqueous environment.
6	Relatively a smaller number of gametes is needed to have a high success rate of reproduction.	A large number of gametes are needed to have a high success rate of reproduction rate.
7	It requires hormones for reproduction.	It is relatively a simple reproduction process and does not require hormones for reproduction.
8	The number of offsprings produced is very few.	A large number of offsprings can be produced.
9	Types of internal fertilization are:- Ovoviviparity: In these animals, the eggs will be maintained in the female’s body and when the eggs become completely developed, it will hatch.- Oviparity: In these animals, eggs will be laid and will undergo development.- Viviparity: In these animals, the off-springs will develop inside the body.	No such types of fertilization will be observed.
10	Example: Human, dogs	Example: Fish, frog

Note:
External fertilization can be artificially performed in humans in certain situations where the egg and sperm cannot fuse to undergo the fertilization process. This type of external fertilization in humans is called in-vitro fertilization.