The five kingdom systems
To cope up with above discussed problem a number of alternative classificatory schemes have been suggested with more than two kingdoms. The one which has gained most support was put forward in 1969 by the American Wologist R.H. Whittaker. Whittaker's scheme divides living organisms into five kingdoms. The anima14kingdom is reserved for multicellular motile organisms which feed heterotrophically, the plant kingdom for multicellular organisms which feed by. photosynthesis. The protozoa and unicellular algae are brought together into a separate kingdom, the Protista kingdom and the bacteria with blue-green algae, unique amongst living things in being prokaryotic, are combined together in the Monera Kingdom (Fig 3.6). Though five kingdom system solves many difficulties but it also creates some. For example, separating the unicellular algae from the simpler multicellular algae is not entirely satisfactory as they have certain features in common. This has led some biologists to suggest that all algae, unicellular and multicellular, should be included in the protista kingdom. In this scheme even quite complex organisms such as seaweeds would find themselves with the protists, traditionally associated with unicellular organisms. Some biologists feel that the name protist should not be used for this expanded group and it has been suggested that this