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THE LIVING WORLD
Life can be defined as a unique aggregation of molecules
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The basic purpose of these
reactions is to transform or produce and utilize energy
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Through metabolism, various biomolecules are synthesized resulting in growth, development,
responsiveness, adaptations and reproduction
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These living beings live in almost all possible habitats like forests, mountains, deserts, oceans, freshwater bodies,
hot springs, polar regions etc
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All living beings share characteristics like organization, energy utilization, regulation or homeostasis, growth,
development, reproduction and adaptation
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1 WHAT IS GROWING
Life has maintained certain fixed properties that life exhibits today and are very different from those that were
present at its origin
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1
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All living organisms have the capacity to grow
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Increase in body mass
2
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In plants, growth occurs continuously throughout their lifespan
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However, cell division occurs to replace lost cells
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Non-living objects grow by accumulation of material (increase in mass) on the surface
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So growth cannot be taken as a defining property of
living organisms alone
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2
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Fungi multiply and spread easily by producing millions of asexual spores
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Planaria, a flat worm regenerates the lost part of its body and become a new one
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In unicellular organisms reproduction is synonymous with growth, i
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, increase in number of cells
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Many organisms do not reproduce - e
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mules, worker bees, infertile human couples, etc
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3
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All the chemical reactions taking place in our body come under metabolism
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All living organisms show metabolism
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4
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The cells perform all functions in the organism
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Therefore, it can be seen that a cellular organization gives rise to the functions of
life-like metabolism, growth, reproduction, etc
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5
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It is present in living organisms
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Plants respond to external factors like light, temperature, water,
pollutants, other organisms etc
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Therefore, all organisms are ‘aware’ of their surroundings
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Human is the only organism having self-consciousness i
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aware of himself
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All living organisms are linked to one another by the sharing of common genetic material to varying degree
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2DIVERSITY IN THE IVING WORLD:
Earth provides the physical base for living beings
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There are also many organisms that we cannot see with our naked eye around us
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Number of species identified and studied is 1
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8 million
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This natural
diversity of life on earth is generally called biological diversity or biodiversity
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Systematics is a branch of science that deals
with identification, nomenclature, classification and evolutionary history of an organism
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Systematics is as old as
human civilization
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P de Candolle in 1813
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Systema Naturae is the book written by Linnaeus
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This concept
was developed by Julia Huxley in 1940
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Identification: is to determine the exact place or position of an organism in the set plan of classification
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Classification: It is the placing of an organism or a group of organisms in category according to a particular
system and in conformity with a nomenclature system
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•
•
•

Nomenclature (naming): The naming of living organisms is called nomenclature
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Local names-Locally used names are called as local names
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Local names are easy to use by local people, but these local names cannot be used by biologists due to
the following draw backs
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A single local name is often used for many species
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The local names sometimes lead incorrect meaning about the organism
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Different local names are used to recognize an organism in different regions of country or world
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Scientific names: These are the names given to the organisms by biologists based on agreed principle and
criteria
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To accomplish this, certain international codes have been
established
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He is the founder of binomial system
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g
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Mangifera is the genus name and indica is the species name
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Rules:
1
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2
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3
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4
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5
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6
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7
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Eg: Mangifera indica- Mangifera is the genus name and indica is the species name
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3 TAXONOMIC CATEGORIES:
The term taxon was introduced for the first time by ICBN in 1956
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TAXONOMIC HIERARCHY:
The system of arranging organisms in a definite sequence of various taxonomic categories arranged in
a proper descending order is called taxonomic hierarchy
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The hierarchy includes seven obligate
categories
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3
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So the basic unit of taxonomy is
species
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Species is a group of individuals resembling one another
in all major vegetative and reproductive characteristics
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In 1964, Ernst Mayr defined species
as a group of potentially interbreeding populations that are reproductively isolated from other such
groups
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Eg: sapiens
1
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2Genus: A group of related species
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E
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: Homo
1
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3 Family: A family is an assemblage of related genera
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g
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3
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E
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: Primata
1
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5 Class: Several related orders having certain common characters form a higher category called the
class
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g
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3
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The term phylum is used in the case of
classification of animals and the term division is used in plant classification
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g
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3
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It includes one or more related
divisions or phyla
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E
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: Plantae, Animalia
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4 Taxonomical Aids:
They are useful in agriculture, forestry and industry
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Taxonomic work involves studies both in field and in laboratory
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The important taxonomic aids are herbaria, botanical gardens, museums, zoological parks and keys
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4
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Herbarium:
It is a depository of plant specimens in dry condition
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Procedure:
1
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Pressing and drying: to remove moisture content
3
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Mounting: Pasting or stitching on a sheet
5
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6
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Each herbarium sheet is to be labeled properly to avoid confusion
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The label
is pasted on the right hand corner at the bottom of the herbarium sheet
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It gives a list of total plant species in a particular region together with a brief description of the same
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The largest Herbarium of the world is Herbarium of Royal Botanical Garden at Kew in England
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1
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2 (B)
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A botanical garden contains plant species from various corners of the world
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Each plant is labelled
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Botanical garden has green houses, a library, a herbarium, research laboratory etc
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At present there are over 600 botanical gardens in the world
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The largest Botanical Garden of the world is Royal botanical garden at Kew in England
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Bentham and Hooker were associated with this garden
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The largest tropical botanical
garden in Asia is Tropical Botanical Garden at Thiruvananthapuram in Kerala
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4
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There are natural science museum, Science museum and Zoological museum
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Animals are also preserved in museums
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The
specimens are correctly identified and labeled
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Plants and animal specimens are also preserved as dry specimens
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Birds and mammals are stuffed and preserved
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1
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5 (D)
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It is
prepared by a taxonomist to help other biologists to identify the species
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The characters are in a pair called couplet
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If a key provides sequence of choices between two or more statements of characters of species, it is called
indented key
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If the pairs of contrasting characters are not repeated by subdividing characters and each character is given a
number in bracket, it is called bracketed key
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Zoological parks:
Zoological parks are the places where animals are kept in protected environment under human care
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The largest zoo in the world is the zoological park of Kruger in South Africa
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OTHER TAXONOMIC AIDS: Besides the above mentioned taxonomic aids, flora, manuals, monographs
and catalogues also serve as taxonomic aids for correct identification
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It
provides the index to plants occurring in a particular area
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Monograph: These are hand books which provide the available information of any one taxon (family or
genus)
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They
also help in correct identification
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The publications publish the books, periodicals, and
dictionaries which provide new information for taxonomic studies
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The organisms exhibiting metabolism, cellular organization, homeostasis, growth, reproduction, development,
responsiveness and other characteristics of life are designed as living things
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Growth is an irreversible increase in the mass of an individual
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Systematics deals with identification, nomenclature, classification and evolutionary history of an organism
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Identification is to determine the exact place or position of an organism in the set plan of classification
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Classification is an arrangement of organisms into groups on the basis of similarities
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Nomenclature deals with the determination of a scientific name of organisms using international code of
nomenclature
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Binomial nomenclature- The system of naming with two components or epithets –generic and specific epithet
and is proposed by Carolus Linnaeus
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The sequence of arrangement of these taxonomic categories in their order is known as taxonomical hierarchy
and each level in the hierarchy is known as taxon
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Taxonomic hierarchy is the sequence of taxonomic categories in a descending order of number of species
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Taxonomical aids- Techniques and procedures to store information and specimens for identification and
classification of organisms
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Herbarium is a storehouse of dried, pressed, and preserved plant specimens
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Museum has collection of preserved plant and animal specimens
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Botanical garden has collection of living plants
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Zoological parks are the places, where wild animals are kept in protected environment under human care
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Key is used for identification of plants and animals, based on similarities and differences
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Flora is a book or other work dealing the plants of a particular region or habit
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Monograph gives comprehensive information of a single taxon in biological studies
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Manual provides information for identification of name of species found in a particular area

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