LIFE SCIENCE

Detailed explanation-1: -The classical cell theory was proposed by Theodor Schwann in 1839.

Detailed explanation-2: -published from Berlin Mikroskopische Untersuchungen, in which he demonstrated that Schleiden’s conclusion also applies to animals, thus establishing the cell as the elementary unit common to both plant and animal kingdoms.

Detailed explanation-3: -The cell theory was proposed by two scientists-Schleiden (1838)and Schwann (1839). It says that all the plants and animals are composed of cells and the cell is the basic unit of life. The cell theory was further expanded by Virchow (1855) by suggesting that all cells arise from pre-existing cells.