022 6236 4602

The Fundamental Unit of Life

Tutormate > CBSE Syllabus-Class 9th Biology > The Fundamental Unit of Life

01 What Is The Living Being Made Up Of?

  • All organisms are made of tiny building blocks which are known as cells.
  • In fact, the cell is the basic structural and functional unit of living organisms.
  • However, cells are invisible to the naked eye.
  • Organisms that contain only one cell are thus, invisible to humans.
  • They are known as unicellular organisms.
  • But some organisms are made up of many cells and are known as multicellular organisms that can be easily spotted like birds, trees and human beings.
  • Also, it is the lowest level of organization that is alive.
  • The term cell was derived by Robert Hooke from a Latin word which means ‘little room’.
  • The size and shape of cells are related to the specific function they perform.
  • So some cell like Amoeba change their shape quite frequently while in most of the other cases, the cell shape is more or less fixed.

Discovery of Cell:

  • Robert Hooke, an English natural philosopher discovered cells in 1665.
  • It is derived Latin word which means small room.
  • He saw that the cork resembled the structure of honeycomb consisting of many little compartments.
  • All living forms on earth are composed of one or many cells that perform individual functions.

Types of Organisms:

  • A wide variety of living beings inhabit the earth.
  • Among these, the unicellular organisms require microscope to be identified.
  • However, many organisms are yet to be discovered and a lot more are going extinct.
  • The tiny organisms composed of only a single cell and hence are aptly named unicellular organisms.
  • On the other hand, organisms are made of more than one cell are called multicellular.
  • They represent only a tiny fraction of life on Earth.
  • For example, most plants, animals, and fungi that is visible to us.
  • The various cells in a multicellular organism are integrated and independent to various degrees.
  • Cellular specialization and division of labor are responsible for development of multicellular organisms.
  • These cells become efficient in one process and are dependent upon other cells for the necessities of life.
  • In that way, multiple cells work together in coordination and keep an organism alive and in as perfect condition as possible for their survival.

Differences between unicellular and multicellular organisms:

Unicellular organisms Multicellular organisms
Organisms that consist of a single cell are called single celled organisms or unicellular organisms. Organisms that consist of large number of cells are called multicellular organisms.
A single cell performs all the activities in a unicellular organism. Different cells perform different activities in a multicellular organism.
As a single cell performs all life activities, there is no division of labour. As cells are specialized to perform different functions of the body, there is a division of labour within cells.
Reproduction consumes a single cell. Only some cells of the body called germ cells take part in reproduction whereas other cells (somatic cells) remain intact.
The life span of a unicellular individual is short. The life span of a multicellular individual is long.

Start your learning Journey !

Get SMS link to download the app