Question

Explain the basis for grouping the organisms into five kingdoms.

Answer 1

Hint: R.H Whittaker proposed this five kingdom classification of living organisms, on the basis of Linnaeus’ system of classification - including mode and source of nutrition, cell structure, and body organisation as the main features.

Complete Answer:
The five kingdoms are,
(I) Monera - These are prokaryotic organisms
(II) Protista - These are eukaryotic, single celled and multicellular organisms
(III) Fungi - These are eukaryotic, multicellular organisms and includes yeast, moulds, etc
(IV) Plantae - These are eukaryotic, multicellular organisms which are capable of performing photosynthesis
(V) Animalia - These are eukaryotic and multicellular organisms and comprises humans and various kinds of animals, insects, birds, fishes.

The basis of grouping organisms into five kingdoms is as follows:
- Mode and source of nutrition : Organisms are divided into autotrophic and heterotrophic based on mode and source of nutrition.
- Cell wall : Heterotrophs in which the cell wall is present, are under the kingdom fungi.
- Autotrophs in which the cell wall is present, are under the kingdom Plantae.
- Organisms in which the cell wall is absent are taken in the kingdom Animalia.
- Number of cells : These include unicellular and multicellular organisms. Unicellular eukaryotes form the kingdom Protista, and multicellular eukaryotes form the kingdom of Fungi, Plantae, and Animalia.
- Cell Structure : There are two broad categories on the basis of cell structure: eukaryotes and prokaryotes. All prokaryotes are under the kingdom Monera and all others come under other kingdoms.

Note: As both, fungi as well as plants, contain a cell wall, they are included into different kingdoms on the basis of their modes of nutrition. Fungi are saprophytes (obtain nutrients directly from wastes or dead organic matter), whereas plants are autotrophs (can feed themselves, without the help of any other organism).