Question

How is the five - kingdom classification advantageous over the two kingdom classification?

Answer 1

5 kingdom classification

The five kingdom classification used the following features to classify organisms-

• Structure of cells
• Unicellular and multicellular organism
• Mode of nutrition
• Phylogenetic relationship

The 5 kingdoms are

• Kingdom monera includes prokaryotic bacteria and BGA.
• Kingdom protista includes unicellular eukaryotes.
• Kingdom fungi includes multicellular fungi
• Kingdom plantae includes all multicellular plants and algae.
• Kingdom animalia includes all multicellular animals.

Two kingdom classification

• Based on the presence or absence of a cell wall the whole living world was divided into only two kingdoms-kingdom plantae and kingdom animalia.

Demerits of the two kingdom classification

• Prokaryotes and eukaryotes were grouped together. Example-bacteria and the blue-green algae (cyanobacteria) were placed with other eukaryotes.
• Unicellular and multicellular organisms were grouped together.
• Plants with cell walls composed of cellulose and fungi having chitinous cell walls were placed together.
• Autotrophic or photosynthetic (green algae) and non-photosynthetic, saprophytic (fungi) organisms were put together in the same kingdom plantae.
• Certain organisms did not fall into either category (Euglena).

Merits of the 5 kingdom classification

• Prokaryotes and eukaryotes were placed in different groups.
• Unicellular and multicellular organisms were placed in different groups.
• Fungi are placed in a separate kingdom as their mode of nutrition differs significantly from all other plants.
• Autotrophs and heterotrophs are mostly placed separately.
• Phylogenetic relationship is taken under consideration.