BOTANY

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: -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-3: -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.

Detailed explanation-4: -Theodor Schwann, (born December 7, 1810, Neuss, Prussia [Germany]-died January 11, 1882, Cologne, Germany), German physiologist who founded modern histology by defining the cell as the basic unit of animal structure.

Detailed explanation-5: -Matthias Jacob Schleiden and Theodor Schwann were German scientists. Schleiden was a botanist, and Schwann was a physiologist. In 1835 both Schleiden and Schwann worked in the laboratory of zoologist Johannes Müller. The two became friends and eventually collaborated.