AP BIOLOGY

Detailed explanation-1: -The classical cell theory was proposed by Theodor Schwann in 1839. There are three parts to this theory. The first part states that all organisms are made of cells. The second part states that cells are the basic units of life.

Detailed explanation-2: -Theodor is the person who said animals are made up of cell and Mattias is the person who said plants are made up of cell .

Detailed explanation-3: -German scientists Theodore Schwann and Mattias Schleiden studied cells of animals and plants respectively. These scientists identified key differences between the two cell types and put forth the idea that cells were the fundamental units of both plants and animals.

Detailed explanation-4: -By the late 1830s, botanist Matthias Schleiden and zoologist Theodor Schwann were studying tissues and proposed the unified cell theory. The unified cell theory states that: all living things are composed of one or more cells; the cell is the basic unit of life; and new cells arise from existing cells.

Detailed explanation-5: -Schwann made most of his important scientific discoveries during the Berlin period (1834–1838). In 1836 he isolated the enzyme responsible for digestive processes in the stomach-and coined the name “pepsin” for this newly identified substance.