Sexual reproduction is the production of a new organism from two parents by making use of their sex cells or gametes. In this process male gametes fuses with a female gamete to form a new cell called ‘zygote’. This zygote then grows and develops in to a new organism in due course of time. Sometimes sex cells or gametes are also called as germ cells. The humans, fish, frogs, cats, dogs etc. all reproduce by the method of sexual reproduction.