In a multicellular organism, organs carry out a variety of life functions. In a single-celled organism, these functions are performed by

Organelles

Cell is the most basic unit of matter that can carry out all the processes of life however not all cells are alike. The different structures found within the cell is called the organelles and are assigned to perform specific function in the specific cell. It is also said that organelles maintain the life of the cell. The organelles of a single cell like the organs of a multicellular organism is very essential for the survival of the body. The presence of organelles in both unicellular and multi-cellular organisms are very essential in orde to maintain life and carry on with its individual functions.