What is living? Classification of Organisms

What is living?

● The word living cannot be defined. 
● living organisms mostly used solar energy. 
● There are certain characters by which living can be distinguished from non living. 

1. Growth: Increase in the number of cell or mass is called growth. 
2: Reproduction: Living organism produce young ones of their same kind.
3: Metabolism: Chemical reaction occurring inside a living cell.
4: Response of stimuli : Living have the ability to sense, the condition of their surrounding and respond to these stimuli. 
● When we touch leaves of " Touch me not" plant they close, these movement are called sesmonastic movement. 
● Life on earth is originated by chemosynthesis was proved in laboratory by the scientist. 
● J.B.S. Haldane suggested that life must have developed from simple inorganic molecule. 


Classification of Organism

● There are millions of organisms. It is impossible to study each individual separately. Classification means to categories organism into different groups. Study of an individual of a group gives us the idea of rest of the member of that group. 
● Linnaeus divide all organism into two kingdoms ___ planate and Animalia in his book " Systema Nature".The foundation of modern classification system was laid in the line of classification system started by Linnaeus. Therefore Linnaeus is called ' Father of Taxonomy'. Due to disputed position of organism like bacteria, virus, fungi and euglena, there is a need of reconsideration of system of classification. 
● The book ' Genera plantarium' was written by Bentham and Hooker.

Five Kingdom classification 

● Five Kindom Classification was proposed in 1969 by R.H. Whittaker. The criteria of classifying organism into five Kingdoms are complexity of cell structure, complexity of body of organism, mode of nutrition, life style and phylogenetic relationship.

1: Monera: It includes all prokaryotic organism like bacteria, cyanobacteria and archiobacteria. Filamentous bacteria also come under this kindom.All organism of this kingdom are microscopic. 

2: protista: This Kingdom includes unicellular form like Amoeba usually found in aquatic habitats. On the basis of mode of nutrition they are Autotrophic,parasitic and saprophytic.Diatoms, flagellates and protozoa come under this Kingdom. Euglena have both heterotrophic and Autotrophic mode of nutrition. So, it is placed between plant and animal.

3: Fungi : This Kingdom includes non green plants. It has saprophytic nutrition grow on dead and decaying organic matter.The cell wall is composed of chitin.
Example: Mushroom, Mucor, Albugo etc.

4: Planatae: This Kingdom includes all plant except algae, diatoms, fungi and member of monera and protists.

5: Animalia: Almost all animal comes under this Kingdom except protozoan.

●Binomial nomenclature: 

● Binomial nomenclature: There was the need of uniform international naming of organism. In biology every organism is represented by two proper name. The first name is genus, always started with capital letter and the second name is species started with small letter. For example scientific name of human is Home sapiens. 
● Panchanan Maheswari popularised the use of embryological  characteristics in taxonomy. 
● Basic unit of classification is species. 
● Highest unit of classification is Kingdom. 
● Carlos Linnus is the father of taxonomy. 


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