Chemistry

* Aristotle was the first scientist to classify living organisms (plants and animals) scientifically. * Aristotle used simple morphological characters to classify Two Kingdom Classification * Proposed by C. Linnaeus * Hedivided organisms into two kingdoms- Plantae and Animalia. Shortcomings of the system * A large number of organisms did not fall into either of the kingdoms. Three Kingdom Classification * Proposed by E. Haeckel * He introduced a separate kingdom for all unicellular eukaryotes, Protista. * He included fungi, protozoans, algae, bacteria and slime moulds in Protista. Shortcomings of the system * Prokaryotes and eukaryotes were placed together in Protista. * Heterotrophic bacteria and fungi placed along with autotrophic algae. Four Kingdom Classification * Proposed by Copeland * He introduced a separate kingdom, Monera for all unicellular prokaryotes. * The term Monera was given by Daugherty and Allen. Shortcomings of the system * No proper place in this system for fungi. * Other characteristics such as cell structure, mode of nutrition, habitat, methods of reproduction, evolutionary relationships etc. were not included. Five Kingdom Classification * It is the advanced and most popular system of classification. * It was proposed by R. H. Whittaker (1969) * The five kingdoms are Monera, Protista, Plantae, Fungi and Animalia. * It is a phylogenetic system but mainly based on mode of nutrition. * Other criteria for five kingdom classification − cell structure, thallus organization, reproduction and major ecological role. Shortcomings of the system * Both the kingdoms, Monera and Protista include autotrophic as well as heterotrophic organisms. * The three higher kingdoms (Plantae, Animalia and Fungi) do not have a single ancestor. * Members of algae are placed in different kingdoms. * No proper place in this system of classification for viruses. <

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