Biological  

classification  

of  

plants  

and  

animals  

was  

first  

proposed  

by

Aristotle  

on  

the  

basis  

of  

simple  

morphological  

characters.  

Linnaeus

later  

classified  

all  

living  

organisms  

into  

two  

kingdoms  

–  

Plantae  

and

Animalia.  

Whittaker  

proposed  

an  

elaborate  

five  

kingdom  

classification

–  

Monera,  

Protista,  

Fungi,  

Plantae  

and  

Animalia.  

The  

main  

criteria  

of

the  

five  

kingdom  

classification  

were  

cell  

structure,  

body  

organisation,

mode of nutrition and reproduction, and phylogenetic relationships.

In  

the  

five  

kingdom  

classification,  

bacteria  

are  

included  

in  

Kingdom

Monera.  

Bacteria  

are  

cosmopolitan  

in  

distribution.  

These  

organisms

show   

the   

most   

extensive   

metabolic   

diversity.   

Bacteria   

may   

be

autotrophic  

or  

heterotrophic  

in  

their  

mode  

of  

nutrition.  

Kingdom  

Protista

includes     

all     

single-celled     

eukaryotes     

such     

as     

Chrysophytes,

Dinoflagellates,   

Euglenoids,   

Slime-moulds   

and   

Protozoans.   

Protists

have  

defined  

nucleus  

and  

other  

membrane  

bound  

organelles.  

They

reproduce  

both  

asexually  

and  

sexually.  

Members  

of  

Kingdom  

Fungi

show   

a   

great   

diversity   

in   

structures   

and   

habitat.   

Most   

fungi   

are

saprophytic  

in  

their  

mode  

of  

nutrition.  

They  

show  

asexual  

and  

sexual

reproduction.    

Phycomycetes,    

Ascomycetes,    

Basidiomycetes    

and

Deuteromycetes  

are  

the  

four  

classes  

under  

this  

kingdom.  

The  

plantae

includes    

all    

eukaryotic    

chlorophyll-containing    

organisms.    

Algae,

bryophytes,    

pteridophytes,    

gymnosperms    

and    

angiosperms    

are

included  

in  

this  

group.  

The  

life  

cycle  

of  

plants  

exhibit  

alternation  

of

generations    

–    

gametophytic    

and    

sporophytic    

generations.    

The

heterotrophic  

eukaryotic,  

multicellular  

organisms  

lacking  

a  

cell  

wall  

are

included   

in   

the   

Kingdom  

Animalia.  

The   

mode   

of   

nutrition   

of   

these

organisms  

is  

holozoic.  

They  

reproduce  

mostly  

by  

the  

sexual  

mode.

Some   

acellular   

organisms   

like   

viruses   

and   

viroids   

as   

well   

as   

the

lichens are not included in the five kingdom system of classification.