In this video we explaining THE LIVING WORLD in simplified manner for NEET ASPIRANTS


What is living? ; Biodiversity; Need for classification; Three domains of life;
Taxonomy & Systematics; Concept of species and taxonomical hierarchy; Binomial nomenclature; Tools for study of Taxonomy – Museums, Zoos, Herbaria, Botanical gardens

NEET QUESTION FROM THIS CHAPTER~1 or 2 Board examination questions~3%

Unique Features of all Living organism:-
Life span

  • In plants, this growth by cell division occurs continuously throughout their life span.
  • In animals, this growth is seen only up to a certain age. However, cell division occurs in certain tissues to
    replace lost cells.
  • Unicellular organisms grow by cell division
  • In majority of higher animals and plants, growth and
    reproduction are mutually exclusive events.
  • In living organisms, growth is from inside
  • Increase in body mass is considered as growth.
  • Growth,cannot be taken as a defining property of living organisms. 
  • Reproduction is a characteristic of living organisms.In multicellular organisms, reproduction refers to the production of
    progeny possessing features more or less similar to those of parents.
  • Two type of reproduction,sexual and asexual
  • Fungi multiply and spread easily due
    to the millions of asexual spores they produce.
  • In Planaria (flat worms): True regeneration
  • The fungi, the filamentous algae, the protonema of mosses, all easily multiply by fragmentation.
  • Bacteria, unicellular algae or Amoeba, reproduction is synonymous with growth, i.c., increase in number of cells.
  • There are many organisms which do not reproduce (mules, sterile worker bees, infertile human couples, etc
  • Reproduction cannot be an all-inclusive defining characteristic of living organisms.
  • No non-living object is capable of reproducing or replicating by itself.
  • The sum total of all the chemical reactions occurring in our body is metabolism.
  • No non-living object exhibits metabolism.
  • An isolated metabolic reaction(s) outside the body of an organism, performed in a test tube is neither living nor non-living.
  • Hence, while metabolism is a defining feature of all living organisms without exception, isolated metabolic reactions in vitro are not living things but surely living reactions.Hence, cellular organisation of the body is the defining feature of life forms.
  • The most obvious and technically complicated feature of all living organisms is this ability to sense their surroundings or environment and respond to these environmental stimuli
  • which could be physical, chemical or biological. Photoperiod affects reproduction in seasonal breeders.
  • Human being is the only organism that is aware of himself, i.e., has self-consciousness.
  • Consciousness is the defining property of living organisms.
  • The number of species that are known and described range between 1.7-1.8 million. This refers to biodiversity
  • Largest group is insecta.
  • Maximum Biodiversity is found in tropical rain forest:
  • Around 1500 new species discovered every.
  • There is a need to standardise the naming of living organisms
    such that a particular organism is known by the same name all over the
    world. This process is called nomenclature.
  • Nomenclature or naming is only possible when the organism is described correctly and we
    know to what organism the name is attached to. This is identification.
  • Binomial nomenclature system given by CarolusLinnaeus.
  • Each name has two components — the generic name and the specific epithet.
  • Tautonyms: If both generic and specific names are same,called tautonyms.
  • Father H. Santapau – Father of Indian Taxonomy.
  • William Roxburgh – Father of Indian Botany and Indian Herbaria.
  • The term taxonomy was coined and used by French botanist A.P. de Candolle (1813) in his book Theorie Elementaire de La Botanique.
  • Nomenclature: Standardize the naming of living organisms
  • International Code for Botanical Nomenclature (ICBN).
  • International Code of Zoological Nomenclature (ICZN).


  • Biological names are generally in Latin and written in italics. They are latinized or derived from Latin irrespective of their origin,
  • The first word in a biological name represents the genus while the second component denotes the specific epithet.
  • Both the words in a biological name, when handwritten,are separately underlined, or printed in italics to indicate their Latin origin.
  • The first word denoting the genus starts with a capital letter while the specific epithet starts with a small letter.
  • Name of the author appears after the specific epithet, i.e., at the end of the biological name and is written in an abbreviated form.
  • Characterization, identification, classification and nomenclature are the processes that are basic to taxonomy.
  • The word systematics is derived from the Latin word ‘systema’which means systematic arrangement of organisms.
  • Linnaeus used Systema Naturae as the title of his publication.
  • based on characteristics, all living organisms can be classified into different taxa. This process of classification is taxonomy.
  • The scope of systematics was later enlarged to include identification, nomenclature and classification. Systematics takes into account evolutionary relationships between organisms
  • Each category, referred to as a unit of classification, in fact, represents a rank and is commonly termed as taxon
  • species:Taxonomic studies consider a group of individual organisms with fundamental similarities as a species.
  • Genus comprises a group of related species which has more characters in common in comparison to species of other genera.
  • Family;has a group of related genera with still lessnumber of similarities as compared to genus and species. Families are characterised on the basis of both vegetative and reproductive features ofplant species.
  • order :and other higher taxonomic categories are identified basedon the aggregates of characters. Order being a higher category,is the assemblage of families which exhibit a few similar characters.
  • Class:This category includes related orders.
  • Common classes included in phylum 
  • In plants, classes with a few similar characters are assigned to a higher category called Division.
  • as we go higher from species order to kingdom, the number of common characteristics goes on decreasing.
  • Lower the taxa, more are the characteristics that the members within the taxon share.
  • Higher the category, greater is the difficulty of determining the relationship to other taxa at the same level. Hence, the problem of classification becomes more complex.
  • Herbarium is a store house of collected plant specimens that are dried,pressed and preserved on sheets.The herbarium sheets also carry a label providing information about date and place of collection, English, local and botanical names, family, collector’s name, etc. Herbarium also serve as quick referral systems in taxonomical studies.
  • The largest herbaria in the world are those located inRoyal Botanical Gardens, Kew, London (over 6,500,000 specimens); Harvard’s Gray Herbarium, USA (over 5,000,000 plants) and the New York Botanical Garden(over 70,000,000 specimens) collected from various parts of the world.
  • The largest Indian herbarium is located at Central National Herbarium, Sibpur, Kolkata (over 2,000,000 specimens)
  • Biological museums are generally set up in educational institutes such
    as schools and colleges. Museums have collections of preserved plant
    and animal specimens for study and reference.
  • In India, the National Botanical Research Institute
    (NBRI) Lucknow, Indian Botanical Garden, Sibpur,
    Kolkata and the Indian Botanical Garden and Howrah
    gardens are used by taxonomists and students to identify
    their collection.
  • The first botanical garden for the purpose of science and education was maintained by Theophrastus.
  • Famous botanical gardens are located at Royal Botanical Garden, Kew, London
  • Zoological Parks;These are the places where wild animals are kept in protected environments under human care and which enable us to learn about their food habits and behaviour.The first zoological park was London Zoological Park which was established in 1828 and opened for public in 1847, The largest zoo in the world is located in Kruger,
  • Key :The keys are based on the contrasting characters generally in a pair called couplet. It represents the choice made between two opposite options. This results in acceptance of only one and rejection of the other. Each statement in the key is called a lead.

Leave a Reply

Your email address will not be published. Required fields are marked *