THE LIVING WORLD CLASS 11TH NOTES

 

THE LIVING WORLD

 

IDENTIFICATION: is the finding of correct name and place of an organism in a system of classification. It is done with the help of keys. This is carried out by determining similarities with already known organisms.

 

 NOMENCLATURE: is the science of providing distinct and proper names to organisms so that they can be easily recognised and differentiated from others.

 CLASSIFICATION: is the placing of an organism or a group of organisms in categories according to a particular system which is based on certain easily observable but fundamental characters and in conformity with a nomenclature system. A hierarchy for these all categories.

Ø BINOMIAL NOMENCLATURE: is a system of classification developed by Carolus Linnaeus, a Swedish naturalist. According to this system, each organism is given only one name consisting of two words.

·     ØGeneric name (which designates the genus and written in capital letter)

·       ØSpecies name (indicates species and written in small letters)

Ø {Both words are written in italics or underlined}

v Linnaeus described 5900 species of plants in his book Species Plantarum (1753) and 4326 species of animals in Systema Naturae(1758)

 

 ØSYSTEMATICSis the science that deals with diversity of organisms and their comparative and evolutionary relationships and grouping of organisms at every level of classification right from species to the kingdom.

All living organisms are classified into various groups based on their characteristics according to the principles of identification, nomenclature and classification. This branch of study is known as taxonomy.

ØTaxonomic hierarchy, also called Linnaean hierarchy, as proposed by Linnaeus, is the classification of organisms in a definite sequence of categories (taxonomic categories) in a descending order starting from Kingdom and reaching upto Species or an ascending order from species to kingdom.

Each taxonomic category is referred to as taxon (plural-taxa), which is a unit of classification and represents any level of grouping of organisms. The common categories are:

S vSpecies: A group of individuals with similar morphological characters, which are able to breed among themselves and produce their own kind.

·     vGenus: The first higher category above the species level. It is a group of species, which are related and have few characters in common as compared to species.

·      vFamily: It includes one or more related genera, differentiated from other related families by certain characteristic differences.

·      vOrder: An assemblage of  families resembling one another in few characters.

·      vClass:  It includes one or more related orders.

·      vPhylum (Division):It includes all organisms belonging to different classes having a few common characters. The term Division for Phylum is used by Botanists.

·      vKingdom:  It includes all organisms that share a set of distinguishing common characters . This is the highest taxonomic category.

The number of similar characters in the members of a group decreases from Species to Kingdom i.e., number of species are most similar while that of a kingdom share least common characters.

v Techniques, procedures and stored information that are useful in identification and classification of organisms are called taxonomicaids.

v Image:

 

 

 

PMonographs: Information on any one taxon.

PManuals: information for identifying species in an area.

P Flora: Account of habitat and distribution of plants in a given area.

PCataloguesare some other useful taxonomic aids.