a) Sexual Reproduction and Asexual Reproduction:

b) Gametes and Zygote:

1. Millions of male gametes (sperms) are produced by the testes. These are microscopic and single celled. Sperm has a head, a middle piece and a tail. Ovary produces female gaffietes called ova. It is a single cell, (haploid) 

2. The fusion of male and female garnet is called fertilization. The result of fertilization is the formation of a zygote. Zygote is a diploid cell. This develops mitorically and forms into an embryo, which further develops into a baby.

c) External fertilization and Internal fertilization:

The process of fertilization that occurs outside of an organism is called External fertilization. 

E.g. Frog, Fish, Star fish, etc. The process of fertilization that takes place inside the body of females is called Internal fertilization. 

E.g. Animals, Human beings.

d) Viviparous and Oviparous animals:

Animals which give birth to their off springs are called Viviparous animals.  

E.g. Animals, human beings. Animals which lay eggs are called Oviparous animals. 

E.g. Hen, duck, pigeon, etc.