Respuesta :
The cell theory teaches that all living things are composed of one or more cells; the cell is the basic unit of life.
Answer: The correct answer for the blank is -
Cell is the basic structural and functional unit of all life forms, all living organisms are composed of basic unit called cells, and each cell arise from a previously existing cell.
Explanation -
The Cell theory was proposed by Schleiden and Schwann in the year 1839, according to which -
1) Cell is considered as the basic structural and functional unit of all life forms.
2) All life forms are made up of cell.
3) Every cell arise from a cell that already existed before.
