cellular organization class 9 biology book chepter no 1 topic 1.7

We all know that all living organism are made of cell. Cell
is the basic structural and functional unit of life. Cell can be prokaryotic or
eukaryotic the difference is the presence of membrane bound organelles.
Cellular organization can be of three types.

1)     
Unicellular organization

2)     
Colonial organization

3)     
Multicellular organization

UNICELLULAR ORGANIZATION: example of unicellular organization is
amoeba, chlamydomonas, euglena etc. all these are single called organisms.
Their single cell is capable of respiration digestion, excretion reproduction
etc.

Colonial organization: example of colonial organization is volvox.
They consisting of 500 to 50000 cell. Eyespot that allow them to swim near
light. Flagella for locomotion for moment.

Multicellular organization: they have proper organ system. E.g. are
brassica campestris this the scientific name of mustard plant. Its leave is
used as vegetable and oil is extracted from seeds. They have two part of which
are vegetative part consists of roots stem branches and leaves the reproductive
part which consist of flowers. Another example is rana tigrina the scientific
name of frog. They have proper organ and organ system. Each part has specific
job. Circulatory system work to the digestive system to gets nutrients to the
cell. The nervous system work with the muscular system to help the body
responds to stimuli. The respiratory system work with the circulatory system to
get oxygen to muscles cell and remove carbon dioxide.