Question

Briefly describe the cell theory.


NCERT Class XI
Biology - Exemplar Problems

Chapter 8. The Unit of Life

Answer 1

all living organisms wheather plants or animals, are made up of cells which serve as the units of structure and function. This is known as cell theory.

Answer 2

___________________________________________________________

Cell Theory In 1838,was proposed by Jakob Matthias Schleiden(1804-1881) was a German botanist and Theodor Schwann (1810-1882) was German zoologist.

Scheilden said that-:All plants consists of cell

Schwann said that-:All animals and plants are made up of cells

Cell Theory was refined by R.Virchow.He presented the idea that-:All cells are arise from pre existing cells only.

Thus,Cell Theory's postulates are:_

1-All organisms are composed of cells and cell products.
2-All metabolic reactions takes place in cells.Thus,cell are structural and functional unit of life.
3-All cells are arise from pre existing cells only.
4-Every organism starts its life with single cell only.Viruses are exceptions.

____________________________________________________________

Hope it helps you........Click on thanks (if helps)......plz mark it as the best......and don't forget to comment...:)))