The cells are called as structural and functional units of a living body. Cells are structural unit as they form the structure of the organism. Cells combine to form tissues, which further combine to form organs, organs combine to form organic systems, which further combine to form organism. So, cell is the basic structural unit for all unicellular and multicellular organisms.
Some of the basic �life processes� or �functions� takes place in every cell to keep the organisms alive such as digestion, respiration, excretion, etc., whether it is a single-celled organism or multicellular organism. So, the cells are also called the functional unit of life owing to these processes