Some resources indicate that the following modern addendums have been added to the basic cell theory. The cells within individuals ... are made of only one cell. Unicellular is the term used to define such organisms. ... There is a debate as to whether or not viruses should be considered to be alive. read more
In addition to the cell theory, the gene theory, evolution, homeostasis, and the laws of thermodynamics form the basic principles that are the foundation for the study of life. Cell Basics All living organisms in the kingdoms of life are composed of and depend on cells to function normally. read more
1. All living organisms are composed of one or more cells. 2. The cell is the most basic unit of life. Schleiden's theory of free cell formation through crystallization was refuted in the 1850s by Robert Remak, Rudolf Virchow, and Albert Kolliker. In 1855, Rudolf Virchow added the third tenet to cell theory. read more