A single-celled fertilised egg is called a/an ___________.

A single-celled fertilized egg is called a zygote. “A zygote is formed when a sperm cell fertilizes an egg cell, resulting in the fusion of their genetic material. This single-celled structure marks the beginning of the development of a new organism. In humans, for example, the zygote undergoes rapid cell division through a process called cleavage, eventually forming a blastocyst which implants into the uterine wall. From there, it continues to develop into an embryo and eventually a fetus.”