Two Kingdom System
From
Aristotles to the late 1800s it was traditional to assign every living organism
to one of two kingdoms, either plants or animals. However the two kingdom
system was problematic. It was easy to place photosynthetic organisms e.g. trees,
flowering plants, mosses, ferns in the plant kingdom, and food ingesting motile
forms e.g. worms, fishes, mammals in the animal kingdom. Some forms were
claimed both for the plant kingdom by the botanist and for the animal kingdom
by zoologist e.g. Euglena, which is motile like animal but has chlorophyll and
photosynthesize like plants. Other groups, such as bacteria were arbitrarily
assigned to the plant kingdom.
Three Kingdom System
In
1866 Ernst Haeckel proposed a new kingdom Protista to include all single celled
organisms.
Four Kingdom Systems
In
1937 E. Chattan suggested differentiating term procariotique to describe
bacteria and blue green algae and the term eucariotique to describe animal and
plant cells. In it the four kingdoms are:
1)
Prokaryotes
2)
Plants
3)
Fungi
4)
Animalia
Five Kingdom System
In
1-969 Robert H. Whittaker proposed five-kingdom system that incorporated the
basic prokaryotic- eukaryote distinction.
Five Kingdom System By Margulis And
Schwartz
The
five kingdom system of ‘American biologist R.H. Whittaker has been modified by
Lynn, Margulis and Karlene V. Schwartz in 1988.
Kingdom Prokaryotae (Monera)
In
it all prokaryotic organisms are included. Most are unicellular and relatively
simple in structure. The kingdom includes numerous types of bacteria, and
blue-green algae.
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| Five Kingdom System |
Kingdom Protoctista (Protists)
This
includes eukaryotic organisms with a unicellular or simple multicellular structure.
The most important groups are protozoa, algae and slime molds, and other
Variety of some aquatic and parasitic organisms are included.
Kingdom Plantae
It
includes all the multicellular autotrophs with chloroplast containing
chlorophyll a and b. The life cycle has a diploid embryo stage not seen in
photosynthetic Protoctista.
Kingdom Fungi
It
includes all the fungi, which are eukaryotic organisms. They reproduce by
forming spores and lack cilia and. flagella at all stages of their life cycles.
Kingdom Animalia
It
includes all the animals which are multicellular heterotrophic eukaryotes. The
nuclei of their body cells are diploid, and they reproduce by means of male and
female gametes.
In
the five kingdom classification system of Margulis and Schwartz unicellular and
multicellular algae have been separated, into kingdom Protoctista and kingdom
Plantae.
Nice, thanks for your clear explanations
ReplyDeleteYou are welcome. :):)
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