What does the term "zygote" refer to in biology?

The term "zygote" specifically refers to the fertilized egg, which is the first cell formed when a sperm cell successfully fertilizes an egg cell. At this point, the zygote is diploid, meaning it contains two sets of chromosomes—one set from the mother and one set from the father. This is a crucial stage in the developmental process as the zygote undergoes subsequent cell divisions, eventually leading to the formation of a multicellular organism.

Understanding this concept is fundamental, as it underlines the significance of fertilization in sexual reproduction and the initial step in the development of new life. The zygote marks the beginning of a new organism's existence, transitioning from a single-cell stage to a complex structure through further developmental processes.