AP BIOLOGY

Detailed explanation-1: -Matthias Jacob Schleiden was a German botanist who, with Theodor Schwann, cofounded the cell theory . In 1838 Schleiden defined the cell as the basic unit of plant structure, and a year later Schwann defined the cell as the basic unit of animal structure.

Detailed explanation-2: -Matthias Schleiden proposed that all animals are made up of cells.

Detailed explanation-3: -Matthias Jacob Schleiden helped develop the cell theory in Germany during the nineteenth century. Schleiden studied cells as the common element among all plants and animals.

Detailed explanation-4: -Schleiden and Schwann, who are usually given credit for elucidating the cell theory, made their marks in 1838 and 1839. In 1838 Matthais Schleiden (1804–1881) proposed that every structural element of plants is composed of cells or the products of cells.

Detailed explanation-5: -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.