Step-by-step explanation:
The cell theory suggests that cells come from pre-existing cells. This means that new cells are formed by the division of existing cells. This is a fundamental principle of biology and is supported by numerous observations and experiments. The cell theory was first proposed in the mid-19th century by scientists such as Matthias Schleiden and Theodor Schwann who observed that all living organisms are composed of cells and that cells are the basic unit of life.