The five kingdom system

five kingdom classification in brief

1. THE FIVE KINGDOM SYSTEM PRESENTED BY- Syeda Tamanna Yasmin ( DU2017MSC0130 ) M.Sc. Microbiology 2 nd semester

2. DEFINITION OF KINGDOM In biology, kingdom is a taxonomic rank that is composed of smaller groups called phyla (or  divisions, in plants). Historically, kingdom is the highest taxonomic rank, or the most general  taxon  used in classifying organisms.

3. BIOLOGICAL CLASSIFICATION OF PLANTS AND ANIMALS Biological classification of plants and animals was first proposed by  Aristotle  on the basis of simple morphological characters. Linnaeus (1758)  later classified all living organisms into two kingdoms – Plantae and Animalia . E. haeckal (1866) suggested that the inconsistencies of two kingdom system could be avoid by recognition of third kingdom and he proposed Protista . Copeland (1959) came forward with a four kingdom system to accommodate lower protists i.e. Monera .

4. R.H.Whittaker proposed an elaborate five kingdom classification –  Monera , Protista , Fungi, Plantae  and   Animalia . The main criteria of the five kingdom classification were cell structure, body organisation , mode of nutrition and reproduction, and phylogenetic relationships . He retained bacteria and cyanobacteria under kingdom Monera ,retained microalgae ,protozoa and slime moulds under kingdom protista . He separated fungi completely.

5. BIOLOGICAL CLASSIFICATION INCLUDES: Kingdom Monera Kingdom Protista Kingdom Fungi Kingdom Plantae Kingdom Animalia AT PRESENT, Viruses, Viroids and Lichens

6. KINGDOM MONERA Archaebacteria , bacteria and cyanobacteria . P rokaryotes   Unicellular   They are the most abundant micro-organisms and live in extreme habitats. Some of them have  cell walls [bacteria]  while some do not [ mycoplasma ]. Autotrophic Heterotrophic . Parasites . Lack cell organelles.

7. KINGDOM PROTISTA Single-celled eukaryotes   It form a link that deals with plants, animals and fungi. Chrysophytes , Dinoflagellates , Euglenoids , Slime moulds and Protozoans . Examples are unicellular  algae, diatoms  and   protozoans . Autotrophic or heterotrophic . Primarily aquatic . Some have flagella or cilia that helps in movement . It possess cell organelles. Asexually   and  sexually  by a process involving cell fusion and zygote formation.

8. KINGDOM FUNGI Heterotrophic eukaryotic organisms . Saprophytes . Parasites . They are ubiquitous. Internuclear division. lichens . Mycorrhiza . Glycogen.

9. KINGDOM PLANTAE Most important. Multicellular eukaryotes   Cellulose   . More than 300,000 species. Autotrophs - contains chlorophyll Insectivorous plants  or  parasites . True nucleus. Plantae includes B ryophytes , P teridophytes , gymnosperms  and  angiosperms . Food reserve is usually starch and fat . Non-motile Growth is usually infinite. Sexual and asexual mode of reproduction.

10. KINGDOM ANIMALIA Invertebrate and vertebrate animals,. Multicellular eukaryotes   without cell walls . Heterotrophs . Glycogen or fat . Motile . About 36 phyla Definite shape and size. Higher forms show elaborate sensory and neuromotor mechanism. Most of them are capable of locomotion. The sexual reproduction is by copulation of male and female followed by embryological development.

11. Viruses, Viroids and Lichens In the five kingdom classification of Whittaker there is no mention of some  acellular   organisms :  viruses  and  viroids ,  and  lichens . VIRUSES Not truly living. non-cellula r. obligate parasites . The name virus that means venom or poisonous fluid was given by Pasteur. contain  genetic material. Viruses cause diseases.

12. VIROIDS Viroids are infectious agents that are smaller than viruses. A viroid was found to be a  free RNA ; it  lacked the protein coat  that is found in viruses, hence the name VIROID. LICHENS Lichens are  symbiotic  associations. The algal component is known as phycobiont and fungal component as mycobiont . Lichens are very good  pollution indicator.

13. Merits of R. H. Whittaker 5 Kingdom Classification It is largely the most accepted system of modern class. Separation of prokaryotes into an independent kingdom is justifiable. Grouping of all unicellular eukaryotes under the kingdom Protista has solved many problems, particularly related to the position of organisms like Euglena. Elevation of the group fungi to the status of a kingdom is justifiable. The kingdoms plantae and animalia are now more homogeneous groups than they were in the two kingdom classification as it shows the phylogeny of different life styles. The five-kingdom classification gives a clear indication of cellular organization and modes of nutrition, the characters which appeared very early in the evolution of life.

14. Demerits of R. H. Whittaker 5 Kingdom Classification The kingdoms Monera and Protista include diverse, heterogeneous forms of life. In both the kingdoms there are photosynthetic (autotrophic) as well as non-photosynthetic (heterotrophic) organisms. None of the three higher kingdoms include a single ancestor of all its forms. Multicellular lines have originated from protistants several times. Unicellular green algae like Volvox and Chlamydomonas have not been included under Protista because of their resemblance to other green algae. Slime moulds differ totally from other members of Protista in their general organization. Viruses have not been given proper place in this system of classification.

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