Answer: All living organisms are made up of one or many cells.
Step-by-step explanation:
In 1830s, botanist Matthias Schleiden studied the tissues individually and proposed the cell theory for the first time. According to him all the living beings are made up of cells and cell is the basic unit of life.
As according to him in the cell division he was able to observe that the plants are made up of cells. This observation is indicating towards the fact that all living organisms are made up of one or many cells.