Biological classification and who proposed five kingdom classification

 

BIOLOGICAL CLASSIFICATION

Though plant and animal kingdom have been a constant under all different system of classification the understanding of what groups/ organisms be included under these kingdoms have been changing. The number and nature of other kingdom have also been understood differently by different scientist

HISTORY OF TAXONOMY  

ARISTOTLE  -: 

Father of Biology & Zoology

Aristotle used simple morphological character to classify plants  on the basis of growth habit  Herb , Shrub and Trees .

THEOPHRASTUS  -: 

He is known as Father of ancient plant taxonomy and father of Botany. He classified plants into four groups on the basis of growth habit -

(A) Trees   (B) Shrubs    (C) Under shrubs    (D)Herbs

CAROLUS LINNAEUS  -:

His real name was -Carl Von Linne. On the basis of work in latin his name was Carolus Linnaeus. He is known as the father of taxonomy, father of plant taxonomy, father of animals, plants and binomial nomenclature.

Linnaeus gave Two kingdom classification , with kingdom Plantae and kingdom Animalia which included all plants and all animals, respectively . On the basis of presence or absence of cell wall.

Draw back of two kingdom classification

In two kingdom classification prokaryotes like blue green algae , bacteria and eukaryotes like fungi, algae, bryophyta , pteridophyta,gymnosperm , angiosperm placed together in kingdom plantae and unicellular organisms like chlamydomonas,chlorella and multicellular like organism  spirogyra placed together. Heterotrophic fungi placed with autotrophic green plants , Amoeba and paramoecium placed in kingdom animalia due to absence of cell wall . The main base of two kingdom classification was presence or absence of cell wall but composition of cell wall not considered .

The character that unified this whole kingdom was that all the organisms included in it had a cell wall around their cell. This placed together groups which widely differed in other characteristics .

GEORGE BENTHAM AND JOSEPH DALTON HOOKER  -:

Both Bentham and Hooker are related to Royal Botanical Garden. He was curator and they wrote the book "GENERA PLANTARUM". In this books , Bentham and Hooker gave the natural classification on the basis of spermatophyta classification was actual observation based mainly based on floral characters.

Merits of Bentham and Hooker classification

The classification of Bentham and Hooker was mainly based on Floral characters and natural form al. It is simple classification because this classification is based on actual observations .

Draw back of Bentham and Hooker

in this classification the phylogeny of plant is not considered , because in it, gymnosperms are placed in between dicots and monocots. The sequence of evolution is as follows -:

                           Gymnosperm →  Dicotyledonae → Monocotyledonae

R.H. Whittaker  -:

R.H. Whittaker (1969) proposed a Five kingdom classification. The kingdom defined by him were named as Monera, Protista, Fungi, Plantae and Animalia. The main criteria used by him for classification are -:

Complexity of cell - Prokaryotic and Eukaryotic

Complexity of organism - Unicellular and Multicellular

Mode of nutrition - Heterotrophic and Autotrophic

Reproduction - Sexual and Asexual

Phylogeny - Evolutionary relationship

CARL WOESE -:

The three domain system has also been proposed that divides the kingdom monera into two domains, leaving the remaining eukaryotic kingdom in the third domain and thereby a six kingdom classification .