Question

What is cell theory? Who formulated it?

Answer 1

Hint: The cell theory was given by a German botanist who examined a large number of plants. In 1838, he observed that all the plants are composed of unalike kinds of cells forming the plant tissues. According to this theory, unicellular organisms are capable of independent existence and performing the essential functions of life. There is no universally acquired clarity of life.

Complete answer:
The cell theory was formulated by ‘Matthias Schleiden’ and ‘Theodore Schwann’ in 1839.
- At around the same time, another scientist T. Schwann (1839) who was a British zoologist analyzed different types of animal cells and noticed that the cells had a thin outer layer which is now termed as the plasma membrane.
- He also winds up on the basis of his studies on plant tissues that the presence of a cell wall is a unique characteristic of the plant cells.
- On this basis, he put forward a hypothesis that the bodies of plants and the animals are composed of cells and their products.
- Schleiden and Schwann together produced the cell theory. This theory, however, did not explain how new cells are formed.
- Rudolf Virchow in 1855 first contributed that cells divide and that new cells were formed from pre- existing cells (Omnis cellula- e cellula). He altered the hypothesis of Schleiden and Schwann to give cell theory a final and concluding form.
- Cell theory is understood as:
- All living organisms are composed of cells and products of cells.
- All cells originate from pre- existing cells.
- Actions of an organism are the result of the sum total of activities and interactions of its component cells.

Note: Anything less than an absolute structure of a cell does not make sure for independent living. Thus, the cell is the basic, structural, and functional unit of life. The cell theory was, however, a leading advancement in the field of biology since a little was known about animal structure in comparison to the plants.