Cell structure and function
All organisms, whether simple or complex, plants or animals. are composed of cells. For example, a bacterium or an amoeba is made up of just one cell, while a complex organism like an adult human is composed of hundreds of billions of cells (over 1014 cells). The sum total of the properties of cells in an organism is represented by its appearance, behaviour, activities and functions. It becomes thus, important to study cells for understanding all forms of life.