In 1839, 2 scientists, Mathias Schleiden and Theodor Schwann proposed the cell theory.
It explains the fundamentality of cells and the basis of all life forms.
According to this theory –
Cells are the smallest and the most basic unit of function and structure in all forms of life.
Cells can only be formed from preexisting cells
All organisms are made up of cells.
Final answer
Hence, According to this cell theory –
Cells are the smallest and the most basic unit of function and structure in all forms of life.
Cells can only be formed from preexisting cells
All organisms are made up of 1 or more cells.