Cell - A Unit of Life

Organisms may be broadly classified into two kinds:

• Unicellular

• Multicellular

Ameoba

Chlamydomonas

Paramecium

Cells of onion peelMulticellular lifeform

All living organisms, whether plants or animals, are made up of microscopic units called cells. The cell occupies the same central position in biology as the atom in the physical sciences.

All living beings, plants and animals, start their life with a single cell. Some organisms exist as a single cell and carry out the various metabolic life processes such as assimilation, respiration, reproduction, excretion, etc., that are essential for their survival. These are known as unicellular organisms.

Example:

yeast, bacteria, chlamydomonas, amoeba.

Some cells divide and give rise to organisms with more than one cell, these organisms are termed as multicellular.

Hence, what is a cell?

A cell is the structural and functional unit of all life forms.