Final answer:
A gamete is a haploid sex cell involved in sexual reproduction, with sperm and oocytes being male and female examples, respectively. Fertilization is the union of these gametes to form a diploid zygote, which contains a full set of chromosomes and begins the development of a new organism.
Step-by-step explanation:
A gamete is a specialized sex cell essential in sexual reproduction. In humans and most other organisms, gametes carry half the number of chromosomes found in body cells; specifically, they are haploid cells. The male gamete is known as sperm, which is motile, while the female gamete, referred to as an oocyte, is generally larger and sessile. Meiosis and gametogenesis are biological processes that produce gametes. Fertilization occurs when a male and a female gamete unite to form a zygote, a diploid cell that contains a full set of chromosomes, thereby initiating the development of a new organism.
The Zygote
During the process of fertilization, the pronuclei of the sperm and oocyte combine, creating a zygote with the genetic instructions necessary to develop into a multicellular organism. This single-celled diploid zygote then undergoes mitosis, forming the multicellular offspring. The term 'zygote' encapsulates the initial stage of development that results from the fusion of gametes in sexual reproduction.