1. The Living World

Characteristics of living organisms

 Growth

 Reproduction

 Metabolism

 Cellular organization

 Consciousness



 The number and types of living organisms present on earth is known as biodiversity.

 Total known and described species are between 1.7-1.8 million.



 The process to standardise the naming of a living organism is known as nomenclature.

 The process of assigning a pre-existing individual or class name to an individual organism is identification.

 The system of providing a name with two components (Generic name and specific epithet) is known as Binomial nomenclature.


(An epithet is a word in the scientific name of an organism, following the name of the genus)

 Binomial nomenclature was given by Carolus Linnaeus.

 The biological names are generally in Latin and written in italics (underlined when written by hand). Example: The biological name of mango is Mangifera indica.

 The first word in a biological name (e.g. Mangifera) represents generic name, which always starts with capital letter while the second component (e.g. indica) represents the specific epithet that starts with a small letter.

 IUBN – International Code of Botanical Nomenclature and IUZN – International Code of Zoological Nomenclature are responsible for approving a name and ensuring that the name has not been given to any other plant or animal respectively.



 It is the scientific ordering of organisms in a hierarchical series on the basis of its relationships.



 It is done after finding the correct name and proper position of an organism in a hierarchy.

 Taxon is the scientific term for these categories. It is referred to as the unit of classification. This process of classification is known as taxonomy.

Taxonomy is the branch of biology that deals with identification, naming, and classification of organisms.

 The hierarchical arrangement of various taxonomical categories in descending order is: Kingdom → Phylum (Division)  Class  Order  Family → Genus →Species. All these categories together form a taxonomic hierarchy.


Aid to memory - You can learn this hierarchy using the following mnemonic: Kids Prefer Cheese Over Fried Green Spinach

Ø Kingdom - It is the highest level of classification. Example: Kingdom Plantae includes all plants and kingdom Animalia includes all animals.

Ø Phylum - It is the second highest level of classification. It is comprised of group of related classes. Example: Kingdom Animalia includes phylum Porifera, Coelenterata, Chordata, etc. Term division is used in case of plants.

Ø Class - A phylum/division is divided into many classes. Class is a lower taxonomical category than phylum comprising related orders. Example: Phylum Arthropoda includes class Insecta.

Ø Order - A class is divided into many orders. It is a taxonomical category comprised of related families. For example: Class Insecta includes order Diptera.

Ø Family - Family includes many genera with less number of similarities. An order divides to form many families. For example, the family Felidae includes individuals of genus Panthera and Felis.

Ø Genus - Genus comprises a group of related species having many similar characters. For example, lion and tiger are placed under the genus Panthera.

Ø Species - It is the basic level of classification. It is defined as a group of organisms that is capable of inter-breeding to produce fertile offspring.


Taxonomical aids

 These are the procedures and techniques used to store and preserve information as well as specimens of various plants and animals.

 These help in identification, naming, and classification of organisms.




Ø It is the storehouse of collected plant specimens.

Ø Collected plant specimens are dried, pressed, and preserved on sheets and then arranged systematically according to the universally accepted system of classification.

Ø Herbarium sheet contains label regarding date, place of the collection, scientific name, family, collector’s name, etc. of the specimen.

Botanical gardens

Ø It has the collection of living plant species that are grown for identification and reference.

Ø Each plant contains labels indicating their scientific name and family.

Ø Some famous botanical gardens are Indian Botanical Garden, Calcutta (largest in India), Royal Botanical Garden, Kew (largest in world till date), and National Botanical Research Institute.


Ø It is the repository that has a collection of various plant and animal specimens that are preserved for study and reference.

Ø The organisms are preserved either in preservative solution or in the form of dry specimens.

Ø It often has a collection of skeletons of animals also.

Zoological parks

Ø Wild animals are kept in protected environments.

Ø Provides opportunity for studying the behaviour and food habits of the animals


Ø Keys are used for identification of plants and animals based on similarities and dissimilarities.

Ø Manuals, monographs, and catalogues are other means of recording descriptions.

Ø Manuals help in the identification of names of various species of organisms in a given area.

Ø Monograph is a detailed and well-documented work on any particular taxon.


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