Biological classification is a scientific procedure that includes arranging organisms into a hierarchical series of groups and sub-groups based on their similarities and non-similarities. The Biology word was first used by Lamarck and Treviranus in 1802.
Need Of Classification
It is necessary to classify organisms for several reasons. Aristotle was the first scientist to make an effort scientific basis for classification.
There are millions of species of plants. Plants are divided based on simple morphological features to classify plants such as trees, shrubs, or herbs, In studying the character of this particular class, information about all the plants coming under it is obtained.
- organic evolution is the main evidence.
- To give knowledge of new plant discoveries.
- To give knowledge of plant arrangement.
- A plant found in a particular environment is feudal in size or organs. like – Algae, Fungi
Classification Of System
There are three main types of classification systems.
1. Artificial System- The artificial system consists of knowledge of the colour, form, shape, size, location, and use of animals for humans. one or more examples of artificial systems are- Aquatic Animals, Terrestrial Animals, Domestic Animals, Useful Animals, and Parasitic animals.
2 Natural System- Linnaeus produced the book Systema Naturae In 1758, in which he described a special term for scientific names of organisms, which we call binomial nomenclature. Linnaeus is the father of Modern Taxonomy.
3 Phylogenetic System- Based on phylogeny in this system organisms are divided into
Types of Classification System
Linnaeus has put forward the suggestion of the state classification system. It divides all living organisms into two kingdoms. These are Plantae and Animalia.
Kingdom Plantae
- These are multicellular organisms. Cellulose is present around the cells or vacuoles are found in cells. They make their food by photosynthesis, that is these group organisms are autotrophs. They stored food in the form of starch. These cells are Eukaryotes. The cell wall is present. Such As- Algae, Furn.
Kingdom Animalia
- These are multicellular animals. Animalia group of organisms are not making their food by Photosynthesis. There has no cell wall. There are no inorganic crystals available in their cells. The central vacuole is absent. Growth is limited and well-defined growing points are not present. Only a heterotrophic mode of nutrition is available. Excretory organs are present such as-nervous system and sense organs. glycogen is used as reserve food.
Three Kingdom Classification System
J. Hogg and Ernst Haeckel, 1860 The idea of Kingdom Protoctista for all unicellular organisms and Kingdom Plantae or Metaphytes for multicellular plants and Kingdom Animalia or Metazoa for multicellular animals in the three kingdom system, in 1860.
Four Kingdom Classification System
After the three Kingdom classifications, the suggestion of four Kingdom classifications was observed. In this classification, the kingdom of Monera or Protista was recognized in place of Protoctista by Herbert F. Copeland
in 1938. Finally, Fungi was also placed in the kingdom Fungi before Plantae.
1 Kingdom Monera
- These are unicellular prokaryotes cell incipient Nucleus is present. for example- Bacteria, Cyanobacteria
2 Kingdom Protista
- These are unicellular and colonial. They are Eukaryotes Nucleus Is present in the kingdom Plantae. Many protist organisms live in water, and many protists live in moist soil or even in the body of humans and plants. Motion is often by flagella or cilia. For example-Amoeba, Euglena
3 Kingdom Fungi
- These are multicellular and Heterotrophic organisms. Mycelium is present. The Cell Wall is made up of Chitin. Photosynthesis is absent. Such as-Rhizopus
Five Kingdom Classification
This classification was established in 1969 by American scientist R.H. Whittaker. There were the main criteria for classification:
- Cell Structure-Cells are two types. One is eukaryotes and the second is prokaryotes. Eukaryotes nuclei are present. Nucleus missing in prokaryotes cell., Body Structure- one or more organisms are unicellular and multicellular, Life Cycle of Organisms, Phylogenetic Relationship, Reproduction
Property |
Monera |
Protista |
Fungi |
Plantae |
Animalia |
| Cell Type | Prokaryotes | Eukaryotic | Eukaryotic | Eukaryotic | Eukaryotic |
| Cell wall | Polysaccride+ amino acid is the main component of the monera cell wall | the cell wall is Present | made up of Chitin | made up of Cellulose | the cell wall is Absent |
| Structure Complexity | Unicellularcomponents | Unicellular | Multicellular | Multicellular | Multicellular |
| Mode of Nutrition |
Chemosynthetic Autotropic/heterotropic |
Autotrophic/heterotropic | Heterotropic | Autotropic | Heterotropic |
Six Kingdom Classification
Carl Woese gave the Six Kingdoms classification system in the year 1990. He was a professor in the Department of Microbiology at the University of Illinois. It was also called the three-domain system because it classified organisms into three domains, that is, Archaea, Bacteria, and Eukarya.
It mainly used the basic principles of the Five Kingdom system but split Monera into two domains Archaebacteria, Eubacteria, and other Eukaryotes in the Third Kingdom.
1. Archaea
Archaebacteria include prokaryotic organisms and they are unicellular. These consist of a monolayer core of lipids in the cell membrane and their 16S RNA containing different nucleotides. These are methanogens, halophiles, or thermoacidophiles.
2. Bacteria
The bacterial domain contains typical prokaryotes that lack membrane-covered cell organelles. They do not contain microchambers to separate the different metabolic activities. It consists has a single kingdom-Eubacteria.
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Kingdom-Eubacteria
The members of this kingdom have peptidoglycan cell walls all, naked DNA in coiled form, and glycogen food reserves. There is no sap vacuole and 70S ribosomes are present. The members of this kingdom are bacteria, mycoplasma, Actinomycetes, rickettsiae, spirochaetes, cyanobacteria, and Firmicutes.
3. Eukarya
The domain eukarya contain all the eukaryotes. The four kingdoms of this domain are:
- Protista
- Animalia
- Plantae
- Fungi