The cell is the basic functional and structural unit of life. All the living organisms are composed of cells. All cells are formed by the division of the already existing cells which in terms of biology means reproduction. Every cell of our body comprises of genetic material which is passed down during the process and you will know much more about a cell in this video.

1. TOPIC-INTRODUCTION OF CELL
GRADE 9TH –BIOLOGY BY-GEETAKSHI KATNA

2. Introduction
of Cell
To Know History
of Cell
Cell is a basic
unit of life
Cell Theory
Gadgets to
Study Cells
Shape and Size
of Cell
Scale of life
How can cells
perform distinct
functions in
organisms?
Types of
Organisms on
the Basis of
Number of Cells

3. To Know
History
of Cell
Discovered By
Period of
time
What they discovered?
Robert Hooke 1665
noticed the presence of cells in a cork
slice
Leeuwenhoek 1674
found the presence of living cells in the
pond water
Robert Brown 1831
recognized the existence of a nucleus in
the cell
Purkinje 1839
invented the term ‘Protoplasm’ which is
the liquid present in a cell
Schleiden and
Schwann
1838,
1839
presented the cell theory that all
organisms are actually made up of cells
Virchow 1855
suggested that all cells come from cells
that already exist in nature

4. Cell is a
basic unit of
life!
Just as building is made up of bricks
the body of organisms is made up of
cells.
Cell is called structural unit because
body of all the organisms is made up
of cells.
Cell is considered functional unit of
life because all the functions of body
.(physiological, biochemical. genetic
and other functions) are carried out
by cells.

5. Cell Theory
A cell is the structural and
functional unit of all living
organisms.
All the living organisms are
made up of cells.
Cells are formed from pre-
existing cells.

6. Gadgets to Study Cells
 Microscope----
 Light microscope-magnification
range from 100-1500
 Electron microscope- magnification
range from 1 lakh- 5 lakhs.

7. Shape and Size of Cell
Cells vary in shape and size. They
may be oval, spherical, rectangular,
spindle shaped, or totally irregular
like the nerve cell.
The size of cell also varies in
different organisms. Most of the cells
are microscopic in size like red blood
cells (RBC) while some cells are fairly
large like nerve cells.

8. Scale of
life

9. How can
cells
perform
distinct
functions in
organisms?
Cells are capable of performing multiple
functions in an organism.
A cell contains specific components which
are called Organelles.
Each organelle in the cell can perform
different functions such as making new cells
or clearing the waste of the cell. Thus,
organelles allow a cell to perform several
kinds of activities in an organism.

10. Types of Organisms on the
Basis of Number of Cells
Unicellular
Multicellular

11.  How can
multicellular
organisms
originate from
a single cell?

12. Stay Home, Stay Safe, Study Hard