What is a zygote and how does it play a crucial role in the field of biology?

A zygote is a fertilized egg formed when a sperm cell and an egg cell combine. It plays a crucial role in Biology as it is the first cell of a new organism, containing all the genetic information needed for development. The zygote undergoes cell division and differentiation to form all the cells and tissues of the organism, making it the starting point of life and growth.