Kingdom 3861
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Kingdom is the highest category in the hierarchical classification of organisms created by Carolus Linnaeus around 1750. Linnaeus recognized two kingdoms, plants and animals, a scheme that worked reasonably well for large multicellular organisms but failed as microscopes revealed diverse unicellular organisms. In 1959 Robert Whittaker devised a five-kingdom system that maintained kingdoms Plantae and Animalia but added kingdoms Monera, Protista, and Fungi (see Table).


Characteristic Monera Protista Plantae Fungi Animalia
Internal cell membranes Absent Present (Prokaryotes) Present (Eukaryotes) Present (Eukaryotes) Present (Eukaryotes) Present (Eukaryotes)
Cell wall Present Present or Absent Present Present Absent
Organization Unicellular Unicellular or Multicellular Multicellular Mainly Multicellular multicellular
Mode of nutrition Autotrophs or Heterotrophs Autotrophs or Heterotrophs Autotrophs Heterotrophs Heterotrophs
Representative groups Archaea, eubacteria Protozoa, algae, slime molds Mosses, ferns, seed plants Molds, yeasts, mushrooms Animals with and without backbones
Note: An autotroph is an organism that uses solar energy or energy from inorganic chemicals to make organic molecules. A heterotroph obtains organic molecules by consuming other organisms or their products.

Whittaker placed bacteria in their own kingdom, Monera, because of fundamental organizational differences between prokaryotic bacterial cells, which lack membrane-enclosed nuclei and organelles , and the eukaryotic cells of other organisms that possess internal membranes. Plantae, Fungi, and Animalia consist of complex, multicellular eukaryotic organisms that differ from each other in details of cell structure and in how they secure and process energy. Protista is a collection of single-celled eukaryotic organisms and simple multicellular forms, some animal-like, some plantlike.

Molecular evidence, particularly from ribosomal ribonucleic acid (RNA), suggests that the five-kingdom scheme is also too simple. Some biologists believe that Protista should be partitioned into three or more kingdoms. Similarly, kingdom Monera contains two very biochemically distinct groups of prokaryotes: archaebacteria, and eubacteria. A proposed system acknowledges this ancient evolutionary split by creating a higher level of classification, domain, above kingdom. This system distinguishes three domains: Archaea, Eubacteria, and Eukarya (containing protists, plants, fungi, and animals).

SEE ALSO Animalia ; Archaea ; Eubacteria ; Fungi ; Linnaeus, Carolus ; Plant ; Protisa

Cynthia A. Paszkowski


Margulis, Lynn, and Karlene V. Schwartz. Five Kingdoms: An Illustrated Guide to the Phyla of Life on Earth. New York: W. H. Freeman and Company, 1998.

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Apr 30, 2007 @ 9:09 am
there are 6 kingdoms not 5 this page didnt help me at all it confused me. what is your problem confusing people like that im disscucted in this page.
Hassan Kurd
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Mar 18, 2019 @ 10:10 am
Classification of Plants- The Five Kingdoms
Briefly, the five-kingdom system is based on the three different levels of cellular organization associated with three principals’ modes of nutrition photosynthesis, absorption and ingestion. The five-kingdom proposed comprise of:

Kingdom Prokaryotes (Monera, or bacteria) These are prokaryotic unicellular organisms.

Kingdom Protoctista (algae, Protozoan, Slime Molds) These are eukaryotic predominately unicellular organisms. The kingdom protista examples include Euglena, and Amoeba. This kingdom also includes simple multicellular organisms that are believed to be direct descendent of unicellular protists.

Kingdom Fungi (Mushrooms, Molds, Lichens) These are eukaryotic multicellular reducers for example mushrooms. Those organisms, which are classified as heterotrophic and are absorptive in their nutritional mode are called as Fungi. Most fungi are decomposer that live on organic material, secretes digestive enzymes and absorb small organic molecules which are produced by digestion.

Kingdom Animalia (Animals with or without Back Bone) These are eukaryotic multicellular consumers. Animals live mostly by ingestion food and digesting it within specialized cavities. They lack cellulose and show free movement.

Kingdom Plantae (Mosses, Ferns, Gymnosperms and Angiosperms) These are eukaryotic multicellular autotrophs, making their own food by photosynthesis.
Here, plants are arranged with simple and most primitive in the beginning, while complex and more advanced are taken at the end. This will not only be introduced different basis knowledge about different groups of plants to the reader but also introduced the phylogenetic relationship of these groups.

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