Answer
The basic principles of cell theory are as follows:
1.) All known living things are made up of one or more cells.
2.) All living cells arise only from other cells.
3.) The cell is the simplest structural and functional unit of life.
Work Step by Step
Biologists in the 19th century worked to understand life on the microscopic scale. They noticed that every living thing they looked at was composed of cells and cell products. They also performed experiments to prove that cells only came about from other cells, through cellular division, thus disproving the previous idea of spontaneous generation. Lastly the biologists noted that they couldn't subdivide the cell and still call that bit life. Thus the three basic principles of cell theory were formed.
