Cell is the basic structural and fundamental unit of life. It is known as the building block of life because all the organisms are made up of cells. From unicellular to multicellular, the basic body structure and plan start with cell. Even in case of humans, the development of embryo starts with the formation of a single-cell zygote. The same is in case of plants and other animals. The cellular level of an organism is where the metabolic processes occur that keep the organism alive. Even during division and reproduction, it is cell that divides. It is the group of cells that make up tissues and tissues aggregate to form various organs which inturn give rise to a complete organisms.
