* Cells are the basic unit of life: All living organisms are composed of one or more cells, and these cells are the fundamental building blocks of life.
* Cells carry out all life processes: Individual cells are responsible for all the functions necessary for life, such as metabolism, growth, reproduction, and response to stimuli.
* Organisms are a complex system of interacting cells: The activities of an organism result from the coordinated actions of its individual cells. These cells work together in tissues, organs, and organ systems to maintain the overall function of the organism.
Therefore, the activity of an organism is a consequence of the sum of its cellular activities. This is the fundamental principle of modern cell theory.
