AP BIOLOGY

Detailed explanation-1: -The first part states that all organisms are made of cells. The second part states that cells are the basic units of life. These parts were based on a conclusion made by Schwann and Matthias Schleiden in 1838, after comparing their observations of plant and animal cells.

Detailed explanation-2: -Credit for developing cell theory is usually given to three scientists: Theodor Schwann, Matthias Jakob Schleiden, and Rudolf Virchow. In 1839, Schwann and Schleiden suggested that cells were the basic unit of life. Their theory accepted the first two tenets of modern cell theory (see next section, below).

Detailed explanation-3: -The Cell Theory was first given by M.J Schleiden and Theodor Schwann in 1839. It states that all the living beings whether plants or animals are composed of cells that are from pre-existing cells. However, they failed to explain how new cells are formed.

Detailed explanation-4: -Eventually, Schneidan and Schwann joined forces and started to develop the cell theory. But they disagreed on the third point: that all cells come from preexisting cells. It took a third scientist, Rudolf Virchow, to prove that cells did indeed come from other cells.