Explain the basis for grouping organisms into five kingdoms.

Following points explain the basis of grouping organisms into five kingdoms. Organization of nucleus: Organisms with unorganized nucleus are kept under the kingdom Monera. Those with organized nucleus are kept in other kingdoms. 

Number of cells: 

Unicellular eukaryotes are kept in the kingdom Protista, while multicellular eukaryotes are kept in other kingdoms. 

Mode of nutrition and presence of cell wall: 

Hetereotrophic organisms in which cell wall is present are taken under the kingdom fungi. Autotrophic organisms in which cell wall is present are taken in the kingdom Plantae. Organisms in which cell wall is absent are taken in the kingdom Animalia.

Following points explain the basis of grouping organisms into five kingdoms. 

Organization of nucleus: Organisms with unorganized nucleus are kept under the kingdom Monera. Those with organized nucleus are kept in other kingdoms. 

Number of cells: Unicellular eukaryotes are kept in the kingdom Protista, while multicellular eukaryotes are kept in other kingdoms. 

Mode of nutrition and presence of cell wall: Heterotrophic organisms in which cell wall is present are taken under the kingdom fungi. Autotrophic organisms in which cell wall is present are taken in the kingdom Plantae. Organisms in which cell wall is absent are taken in the kingdom Animalia.

The basis for grouping organisms into five kingdoms are:
`rarr` Complexity of cell structure- There are two broad categories of cell structure. Prokaryotic and Eukaryotic. Thus, two broad groups can be formed, one having prokaryotic cell structure and the other having eukaryotic cell structure. Presence or absence of cell wall is another important characteristic.
`to` Unicellular and multicellular organisms - This characteristic makes a very basic distinction in the body designs of organisms and helps in their broad categorizations.
`to` Cell Wall: Presence and absence of cell wall leads into grouping.
`to` Mode of nutrition - Organisms basically have two types of nutritions- autotrophic who can manufacture their own food and heterotrophic who obtain their food from external environment, i.e., from other organisms). Thus, organisms can be broadly classified into different groups on the basis of their mode of nutrition.

Whittkar has based his scheme of classification of living organisms into five kingdom on four factors:
(i)Comlexity of cell structure : There are two broad categories of cell structure : Prokayotic and Eukaryotic. Thus, two broad groups can be formed- one having prokaryotic cell structure and the other having eukaryotic cell strcuture. Presence and absence of cell wall is another important charcteristics.
(ii) Unicellular and multicellular organisms: This characteristic makes a very basic distinction in the body designs of organisms and helps in their broad categorization.
(iii) Mode of nutrition : Organisms basically have type of modes of nutrition- Autotrophic (they can manufacture their own food) and Heterotrophic (i.e., obtian their food from external environment). Thus, they can be broady categorized into different gropus on the basic of the their modes of nutrition.
(iv) Phylogenetic relationship : Phylogney is the evolutionary history of an organism. It is believed that the simple organisms are primitive and complex organisms are advanced. Thus, primitive and advance nature of organisms also helps in their classification into broad groups. For example, the Monera are believed to have given rise to the Protista, from which the remaining three kindogms of multicellular organisms have evolved.