Five Kingdom Classification

In 1969, R.H. Whittaker proposed organising all life into five kingdoms — Monera, Protista, Fungi, Plantae and Animalia — replacing the older two-kingdom (plant/animal only) scheme. He based the five kingdoms on cell structure (prokaryotic versus eukaryotic), mode of nutrition, mode of reproduction, and inferred phylogenetic relationships, evaluated together rather than any single trait.

As the comparative table shows, Monera alone is prokaryotic; the remaining four kingdoms are eukaryotic. Cell walls are present in Protista (in some members), Fungi and Plantae, but absent in Animalia. Body organisation ranges from purely cellular in Monera and Protista, through multicellular tissue-level in Fungi, up to full tissue/organ/organ-system organisation in Plantae and Animalia. Nutrition also varies: Monera and Protista can be autotrophic or heterotrophic depending on species, Fungi are exclusively heterotrophic (absorbing nutrients from their surroundings), Plantae are autotrophic, and Animalia are exclusively heterotrophic. This framework remained the …