How Organisms develop B5

A zygote is the structure that forms after a sperm fertilizes an egg. The zygote then divides by mitosis to make an embryo. Up to the eight cell stage is where all of the cells are identical these are called embryonic stem cells. The embryonic stem cells could become any different cells e.g. red blood cell, nerve cell, muscle cells. Once they become specialised they can no longer become a different cell. Groups of cells group together to create tissues and the tissues group together to make organs.

Cells become specialised because different genes are switched on…