• Biology is the science of life forms and living processes.
  • The living organisms interact with one another as well as with their physical and chemical environment.
  • The term biology was introduced by G. R. Treviranus and Lamarck (1802).
  • The living organisms occur almost in every habitat on earth.
  • All living beings share certain unified and basic characteristics. These include organisation, energy utilization, regulation or homeostasis, growth, development, reproduction and adaptation.


Living organisms show a great biodiversity and are classified into different kingdoms-Monera, Protista, Fungi, Plantae and Animalia. All of these share the following properties -
  • They have definite organisation.
  • They always have cellular nature so are either unicellular (e.g., Amoeba, Paramecium etc.) or multicellular (e.g., Hydra, man etc.).
  • They show coordination between different parts of body to maintain homeostasis (constant internal environment) inside the body.
  • They have the ability of movements and locomotion.
  • They show metabolic functions in the presence of energy.
  • They have the ability of growth and development.
  • They have specific receptors (e.g., sense organs to receive external and internal stimuli) and specific effectors (e.g., muscles and glands to give specific response).
  • They have regulatory mechanisms (e.g., nervous system and hormones in animals, and only hormones in plants) to maintain homeostasis inside the body.
  • They show adaptations to their environment to increase their chances of survival.
  • They show variations which help in speciation and evolution.
  • They have capacity to reproduce for continuity of their race.
  • They have definite life span (period from birth to death).
  • They undergo ageing after adulthood and then natural death.


  • Living organism is formed of many types of inorganic as well as organic biomolecules.
  • Inorganic compounds include water, minerals etc. and are always micro-biomolecules (small sized, low molecular weight, readily soluble in water and diffusible) while organic molecules may be micro (e.g., monosugars, amino acids etc.) or macro-biomolecules (large sized, high molecular weight, insoluble or slightly soluble and non-diffusible e.g., proteins, fats, nucleic acids, etc.). These both types of biomolecules play important roles in metabolism.
  • Role of Water : Water forms 70-90% of the cellular pool. It forms 65% (about two-thirds) of human body. It is formed of H and O in the ratio of 2:1. 95% of water is found in free state and 5% in combined form in the cell. Water helps in sustaining the life processes.
  • Role of Oxygen : Oxygen is mainly utilized in aerobic respiration of the nutrients inside the mitochondria to produce energy-rich ATP molecules, so it is essential for life. In the absence of oxygen, only 5% of energy available is released.
  • Role of Carbohydrates : Carbohydrates are organic compounds formed of C, H and O generally in the ratio
    of 1:2:1. These are commonly called saccharides (Gk. saccharon = sugar). Carbohydrates are the main storage molecules and most organisms use carbohydrates, as an important fuel, by breaking these bonds and releasing energy to sustain life.
  • Role of Proteins : Proteins are polymeric compounds formed by interlinking of amino acids (monomers) by peptide bonds. Out of about 100 types of amino acids, only 20 types
    of amino acids are of biological importance, so are called Magic-20. Proteins play a vital role in the formation of structures in living organisms. Like carbohydrate and fat, protein can be broken down with the release of energy. Protein is not stored as such in the body and it is only used as a substantial source of energy in condition of starvation.
  • Role of lipids : Lipids comprise a major group of insoluble hydrocarbons having many functions. These are polymers of alcohols (e.g., glycerol) and fatty acids interlinked by ester bonds.
Complex lipids such as true fats are important organic molecules that are used to provide energy.
  • Role of Nucleic acid : These are polymers of nucleotides interlinked by phosphodiester bonds called polynucleotides. Each nucleotide is formed of 3 components: a pentose sugar (e.g., ribose in RNA and deoxyribose in DNA), a phosphate group and an inorganic nitrogen-base (a purine or a pyrimidine).
    DNA acts as genetic material in most organisms and controls the synthesis of structural and functional proteins. RNA also act as genetic material in all plant viruses e.g., TMV and helps in protein synthesis.


  • The term "Systematics" was proposed by Linnaeus in 1735.
  • It includes description of external morphological characters of plants or living organisms. E.g., morphological characters of  root, stem, leaves, flowers.
  • This description is used to know inter-relationship among plants or living organisms.
  • The term systematics, taxonomy and classification are after held as synonyms but technically they carry different meanings.
  • New systematics or Neo systematics or Biosystematics is a new branch. Its name was given by Julian Huxley (1940).
  • New systematics includes description of all the characters (internal) including morphological characters (external) of plants or living organisms. E.g., anatomical characters and cytological characters. It is used to know the inter-relationship among living organisms.
  • Carolus Linnaeus is called father of taxonomy.
  • H. Santapau is called the father of Indian taxonomy.
  • Taxonomy is of 3 types - α, β and ω :
    • In α (alpha) taxonomy, only morphological characters are used for identification and classification of plants.
    • β (Beta) taxonomy involves genetical, anatomical, cytological, palynological, physiological and other characters.
    • Analysis and synthesis of all information and types of data to develop classification system based on phylogenetic relationship is called omega taxonomy.
  • Identification is to determine the exact place or position of an organism in the set plan of classification. It is carried out with the help of taxonomic keys.
  • Classification 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.
  • New systematics is mainly based on evolutionary as well as genetic relationship (experimental taxonomy) as compared to morphological characters.
  • Cytotaxonomy : The use of cytological characters of plants in classification or in solving taxonomic problems is called cytotaxonomy. Cytological characters constitute an important aid to plant taxonomy, especially in determining affinities at the generic and intrageneric levels.
  • Chemotaxonomy : The use  of chemical compounds present in plants for classification or in solving taxonomic problems is called chemotaxonomy or chemical taxonomy. It is based on the chemical constitution of plants. The basic chemical compounds used in chemotaxonomy are alkaloids, carotenoids, tannins, polysaccharides, nucleic acids, fatty acids, amino acids, aromatic compounds etc.
  • Karyotaxonomy : It is based on the characters of nucleus and chromosomes. Pattern of chromosomal bands (dark bands and light bands) is most specific character for classification of organisms.
  • Taxonomy is the study of principles and procedures of identification, nomenclature and classification of organisms.


  • Nomenclature is giving distinct scientific names to various structures including living organisms for their identification.
  • The names are of two types - vernacular (common name) and scientific names.
  • The vernacular names are based on some peculiarity of the organisms, e.g., Kandali (a plant having spines).
  • Scientific names are distinct and specific, they have particular spellings which are not changed.


Three types of nomenclature are polynomial, binomial and trinomial.


According to this system, name of any plant consists of many words.
For e.g., Caryophyllum saxatilis folis  gramineus umbellatus corymbia which means Caryophyllum growing on rocks, having grass like leaves and umbellate corymb flowers.


  • Carolus Linnaeus used this nomenclature system for the first time and proposed scientific name of all the plants and animals. He is the founder of binomial system.
  • Linnaeus proposed scientific name of plants in his book "Species plantarum".
  • In binomial nomenclature, each scientific name has 2 components - generic name (genus) and specific name (species). E.g., Solanum tuberosum (potato), Mangifera indica (mango)
  • The name indicates relationship of a species with others present in the same genus.


  • This system was proposed by Huxley and Stricklandt.
  • According to this system, name of any plant or species is composed of three names-
    • Generic name
    • Specific name
    • Subspecific name (Name of variety)
  • When members of any species have large variations then trinomial system is used. On the basis of dissimilarities, this species is classified into sub-species.
Eg. Brassica oleracea var. botrytis (Cauliflower)
Brassica oleracea var. capitata (Cabbage)
Brassica oleracea var. caulorapa (Knol-Khol)


  • Collection of rules regarding scientific - nomenclature of plants is known as ICBN.
  • ICBN was firstly proposed by Sprague, Hitchcock, Green (1930).
  • ICBN was first accepted in 1961.

  • According to binomial system name of any species consists of two names.
E.g.,  Solanum   tuberosum (Potato)
   ↓         ↓
Generic name         Specific name
  • In plant nomenclature (ICBN), tautonyms are not valid i.e. generic name and specific name should not be same in
    plants  E.g., Mangifera mangifera
But tautonyms are valid for animal nomenclature
(ICZN-International Code of Zoological Nomenclature)
E.g., Naja naja (Indian cobra), Rattus rattus (Rat)
  • Length of generic name or specific name should not be less than 3 letters and not more than 12 letters E.g., Mangifera indica.
Exception : Riccia pathankot ensis - More than 12 letters
  • First letter of generic name should be in capital letter and first letter of specific name should be in small letter, E.g., Mangifera indica.
  • When written with free hand or typed, then generic name and specific name should be separately underlined. But during printing, name should be italicized.
  • Name of scientist (who proposed nomenclature) should be written in short after the specific name
E.g., Mangifera indica Lin.
  • Name of scientist should be neither underlined nor written in italics, but written in roman letters (simple alphabets).
  • If any scientist has proposed wrong name then his name should be written in bracket and the scientist who corrected the name should be written after the bracket.
E.g., Tsuga canadensis (Lin.) Salisbury
Notes:- Linnaeus named this plant as Pinus canadensis.
  • The ICBN recognises several kinds or types, depending on the way in which a type of specimen is selected.
  • Type specimen (Herbarium Sheet) of newly discovered plant should be placed in herbarium (Dry garden).
  • Standard size of herbarium sheet is 11.5 × 16.5 inches.
  • Type specimen (herbarium sheet) are of different types
    • Holotype : Herbarium sheet on which the first description of plant is based.
    • Lectotype : In case of holotype is lost, second herbarium sheet prepared from the original plant is called lectotype.
    • Neotype : In case holotype and original plant is lost then herbarium sheet prepared from some other plant of same species is called neotype.
    • Syntype : In case holotype and original plant is lost then many herbarium sheet prepared from many plants of same species is called syntype.
    • Isotype : It is duplicate of holotype. In presence of holotype a second herbarium sheet prepared from the original plant is called isotype.
    • Paratype : Additional herbarium sheet used in the first description of plant is called paratype. It is prepared from some other plant of same species having some variations.


There are 7 main taxonomic categories. They are obligate categories i.e., they are strictly used at the time of any plant classification.
There are some extra categories, like sub division, sub order, sub family, tribe, sub tribe,. etc. They are not regularly used. They are used only when they are needed.
  • The sequence of arrangement of taxonomic categories in a descending order during the classification of an organisms is called taxonomic hierarchy.
  • Kingdom is the highest and species is the lowest category in this hierarchy.
  • Plant groups or animal groups included in categories are called taxon.
  • Suffix for taxa (Taxon)
Division phyta
Sub division phytina
Class opsida, phyceae, ae
Order ales
Sub-order ineae
Family aceae
Sub family oideae
Tribe eae
Sub tribe inae

Notes: There is no suffix for Genus, Species and Kingdom.


Species is the smallest taxonomic category. It is the basic unit of classification.
John Ray proposed the term and concept of species (1942).

  • Mayr proposed the biological concept of species.
  • According to Mayr "all the members that can interbreed among themselves and can produce fertile offsprings are the members of same species"
  • But this definition of Mayr was incomplete because this definition is applicable to sexually reproducing living beings. There are many organisms that have only asexual mode of reproduction.
E.g., Bacteria, Mycoplasma.
  • The main character in determination of any species is interbreeding. But this character is not used in taxonomy. In taxonomy, the determination of species is based on other characters.
E.g., mainly morphological characters.

  • The static concept of species was proposed by Linnaeus.
  • According to Linnaeus "species is unchangeable" i.e. there is no change in the character of species. The species of present day are same as they were in past and they will remains same in future.

  • This concept was proposed by "Lamarck".
  • According to this concept, "species is always changeable". Changes always occur in the characters of species from one generation to next generation. And these changes are known as "evolution".

  • This concept was proposed by "Aristotle" and "Plato".
  • According to this concept, "there is a definite type or pattern of characters in each species of every living organisms and all the members of species show maximum resemblance with this pattern". (Typological concept is based on single individual of species).

Biotype : Members of same species inhabiting similar environment and having some genetic variations are known as biotypes. Variations found in these members are permanent. These members cannot interbreed among themselves.
E.g., Cauliflower, cabbage, knol-khol are three biotypes of one species.

Ecotypes  : Members of same species inhabiting different environment and having some genetic variations are known as ecotypes. Variations are permanent. These members can interbreed among themselves but due to geographical barrier they cannot interbreed.
E.g., Crow (Corvus splendens) found in different regions are ecotype of one species.

Ecads or Ecophenes : Members of same species having some non genetic variations due to environment is called Ecads. These variations are temporary.
Definition related to species

Allopatric species : Those species that are found in different geographical regions and have geographical barriers between them are known as allopatric species. Geographical barriers are hills, oceans, himalayan mountains.

Sympatric species : The species found in similar geographical regions are sympatric species.


  • Genus is an assembly of related species which involved from a common ancestor and have certain common characters called correlated characters.
  • Potato, tomato and brinjal are three different species but all belong to the genus Solanum. Lion (Panthera leo), leopard (P. pardus) and tiger (P. tigris) with several common features, are all species of the genus Panthera. This genus differs from another genus Felis which includes cats.


  • Family, has a group of related genera with still less number of similarities as compared to genus and species.
  • Families are characterized on the basis of both vegetative and reproductive features of plant species.
  • Three different genera Solanum, Petunia and Datura are placed in the family Solanaceae. Among animals for example, genus Panthera, comprising lion, tiger, leopard is put along with genus, Felis (cats) in the family Felidae.


  • Order being a higher category, is the assemblage of families which exhibit a few similar characters. The similar characters are less in number as compared to different genera included in a family.
  • Plant families like Convolvulaceae, solanaceae are included in the order polemoniales mainly based on the floral characters.
  • The animal order, Carnivora, includes families like Felidae and Cancidae.


  • A class is a subdivision within a phylum made of one or more related orders.
  • Order Primata comprising monkey, gorilla and gibbon is placed in class Mammalia along with order Carnivora that includes animals like tiger, cat and dog. Class Mammalia has other orders also.


Classes comprising animals like fishes, amphibians, reptiles, birds along with mammals constitute the next higher category called phylum. All these based on the common features like presence of notochord and dorsal hollow neural system, are included in phylum Chordata. In case of plants, classes with a few similar characters are assigned to a higher category called Division.


All animals belonging to various phyla are assigned to the highest category called Kingdom Animalia. The Kingdom Plantae, on the other hand, is distinct, and comprises all plants from various divisions.

Table : Organisms with their Taxonomic Categories


  • Taxonomic works involves studies both in field and in laboratory.
  • The correct identification is a primary task for any plant, animal or organisms to be classified.
  • Biologists use herbarium, botanical garden, museums, zoological parks and keys in taxonomic studies.
  • Herbarium is a collection of plants parts that usually have been dried, pressed and preserved on sheets.
  • Botanical gardens are the collections of living plants maintained for reference.
  • Museums have collection of preserved plants and animal specimens for the study and reference.
  • 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. Separate taxonomic keys are required for each taxonomic category such as family, genus and species for identification purposes. Keys are generally analytical in nature.

Major Botanical Gardens, Herbaria and Research Institute
  • Oldest botanical garden is "Padua Botanical Garden" Italy (Established -1545).
  • Largest Botanical garden in the world is Royal Botanical Garden, Kew, Surrey, England, established by William Aiton, 1759.
  • Largest herbarium of the world is "Museum of Natural History" - Paris - with a collection of 8880000 specimens.
  • Largest Botanical Garden of Asia is Indian Botanical Garden, Shibpur, Kolkata. Established by Robert Kyd, 1786.
    • Largest herbarium of Asia is Central National Herbarium located in Indian Botanical Garden, with a collection of 25 lakh specimens.
    • Indian Botanical Garden is famous due to the presence of "Great Banyan Tree" in its campus.
    • In campus of Indian Botanical Garden Botanical Survey of India (BSI) is present which is established by William Rouxburgh 1890. Botanical Survey in India is done by BSI.
  • National Botanical Garden, Lucknow. National Botanical Research Institute (NBRI) is located in National Botanical Garden.
  • Forest Botanical Garden, Dehradun.
Forest Research Institute (FRI)is located in Forest Botanical Garden.
  • Lloyd Botanical Garden - Darjeeling.
  • CDRI - Central Drug Research Institute - Lucknow
  • CAZRI - Central Arid Zone Research Institute - Jodhpur
  • CIMAP - Central Institute of Medicinal and Aromatic Plants - Lucknow
  • IARI - Indian Agriculture Research Inst. (Pusa Inst.) - New Delhi
  • Birbal Sahni Institute of Paleobotany (National Institute of Paleobotany) - Lucknow.


  • Anatomy - Study of internal structure
  • Phycology or Algology - Study of Algae
  • Agrostology - Study of grass
  • Anthology - Study of flowers
  • Agronomy - Study of crops plants.
  • Biochemistry - Study of organic substances, found in living organisms.
  • Biophysics - Study of importance in metabolic reactions of different physical theories
  • Bacteriology - Study of bacteria
  • Bryology - Study of bryophytes
  • Bio-metrics - Study related to different biotic  reactions and their results.
  • Biotechnology - Study of isolation of protoplasm and their culture
  • Cytology - Study of structure and functions of cell
  • Dendrology - Study of tree.
  • Dendrochronology - Study of age of trees
  • Embryology - Study of gametes formation, fertilization and formation of embryo
  • Ecology - Study of inter-relations between  living organism and their atmosphere
  • Evolution - Study of different development process of living organism
  • Economic botany - Study of plants of economic importance
  • Exobiology - Study of presence of possible organism on other planet
  • Euphenics - Study of control of heredity disease
  • Floriculture - Study of culture of ornamental flowers
  • Forestry - Study of forests
  • Genetics - Study of heredity and variations
  • Gymnology - Study of Gymnosperm
  • Genetic engineering - Study of manipulation of genes  for human welfare.
  • Histology - Study of structure of tissues .
  • Horticulture - Study of culture of garden plant, fruits and vegetables
  • Karyology - Study of nucleus
  • Morphology - Study of external characters of plants
  • Mycology - Study of fungi
  • Microbiology - Study of microorganisms
  • Molecular Biology - Study of nucleic acid (DNA and  RNA)
  • Oncology - Study of cancer
  • Physiology - Study of various organ within organisms.
  • Paleobotany - Study of fossil plants
  • Pedology - Study of soil


Contributions - Contributors
  • Cell theory - Schleiden and Schwann
  • Central Dogma of Molecular genetics (Name) - Crick
  • Chromosomal Theory of Linkage - Morgan and Castle
  • Chromosomal Theory of inheritance - Sutton and Boveri
  • Cohesion Theory of Ascent of Sap - Dixon and Jolly
  • Double fertilization of Angiosperms - Nawaschin and Guingard
  • Gene Theory (Linkage of genes) - Morgan
  • Germplasm Theory - Weismann
  • Germ Theory of disease - L. Pasteur
  • Induced fit Hypothesis of enzyme - Koshland
  • Mutation Theory - Hugo de Vries
  • Omnis cellula e cellula - R. Virchow
  • One gene-one enzyme theory - Beadle and Tatum
  • Operon Concept of Gene action - Jacob and Monod
  • Organic evolution - Darwin and Wallace
  • 'Protoplasm is the physical basis of life' (Book) - Huxley
  • Theory of Acquired Characters - Lamarck
  • Theory of Natural Selection - Charles Darwin


Inventions and discoveries - Contributors
  • ATP - Karl Lohmann (1929)
  • Blood groups A, B and O - K. Landsteiner (1900)
  • Blood group AB - de Castello and Sturli  (1902)
  • C3 pathway of plants - Melvin Calvin
  • C4 pathway of plants - Hatch and Slack
  • Chargaff's rule of DNA base composition - Erwin Chargaff
  • First test tube baby - Edwards and Steptoe
  • First vaccination - Edward Jenner
  • Heterothallism in fungi - A. F. Blakeslee
  • Insecticidal properties of DDT - Dr. Paul Muller (1939)
  • Jumping genes (transposons) - Mc. Clintock
  • Patau's syndrome - K. Patau
  • Penicillin - A. Fleming (1920)
  • Photophosphorylation in chloroplast - Arnon
  • TMV virus (discovery) - D. J. Ivanowski
  • Vitamin - Kazimierz Funk (1911)


Link - Between the groups
  • Actinomycetes - Bacteria and Fungi
  • Archaeopteryx - Birds and Reptiles
  • Balanoglossus - Chordates and non-chordates
  • Chimaera (rat or rabbit fish) - Bony and Cartilaginous fishes
  • Club moss - Bryophytes and Pteridophytes
  • Cycas - Pteridophytes and Gymnosperms
  • Gnetum - Gymnosperms and Angiosperms
  • Neopilina - Annelida and Mollusca
  • Ornithorhynchus (Duck billed Platypus) - Reptiles and Mammals
  • Peripatus (Walking worm) - Annelida and Arthropoda
  • Protopterus (Lungfish) - Pisces and Amphibia
  • Rickettsia - Virus and Bacteria
  • Virus - Living and nonliving


  • ABA - Abscisic acid
  • ACTH - Adrenocorticotropic Hormone
  • ADH - Antidiuretic Hormone
  • AIDS - Acquired Immuno Deficiency Syndrome
  • ATP - Adenosine triphosphate
  • ATPase - Adenosine  triphosphatase
  • BMR - Basal Metabolic Rate
  • BOD - Biological Oxygen Demand
  • 2,4-D - 2, 4-Dichlorophenoxy acetic acid
  • DDT - Dichloro diphenyl  trichloroethane
  • DLC - Differential Leucocyte  Count
  • ECG - Electrocardiogram
  • EDTA - Ethylenediamine tetra  acetic acid
  • ELISA - Enzyme-Linked  Immunosorbent Assay
  • FAD - Flavin adenine  dinucleotide
  • FADH - Reduced Flavin adenine  dinucleotide
  • FMN - Flavin mononucleotide
  • GDP - Guanosine diphosphate
  • HIV - Human  Immunodeficiency Virus
  • IAA - Indole Acetic Acid
  • LH - Luteinizing Hormone
  • NAA - Naphthalene Acetic Acid
  • NADP - Nicotinamide adenine  dinucleotide phosphate
  • NOR - Nucleolar organising  region
  • P680 - Reaction centre of  Photosystem II
  • P700 - Reaction centre of  Photosystem I
  • PEP - Phosphoenolpyruvate
  • RBC - Red blood corpuscles
  • RuBP (RuDP) - Ribulose bisphosphate
  • RuBisCO - Ribulose bisphosphate carboxylase oxygenase
  • TMV - Tobacco mosaic virus
  • WBC - White blood corpuscles
  • ICBaN - International Code of Bacteriological Nomenclature.
  • ICVN - International Code of Viral Nomenclature
  • ICNCP - International Code of  Nomenclature for Cultivated Plants.



  • Angiosperm - Eucalyptus (Australian  species, 114m)
  • Animal - Giraffe (Giraffa  camelopardalis)
  • Gymnosperm - Sequoia sempervirens (111.25 m)
  • Monocot plant - Date palm  (Phoenix dactylifera)


  • Angiospermic flower - Wolffia (1.1mm)
  • Angiospermic plant - Lemna (Duckweed)
  • Ape - Gibbon
  • Bird - Hummingbird of Cuba (Helenae)
  • Cell - Pleuro Pneumonia like Organisms (PPLO)
  • Cell of vertebrate - Squamous epithelium
  • Gymnosperm - Zamia pygmaea
  • Number of chromosome in animals - Ascaris (2)
  • Number of chromosome in plant - Haplopappus gracilis (2n = 4)
  • Pollen grain - Orchid
  • Pteridophyta - Azolla


  • Bone of man - Femur
  • Cell - Neuron
  • Creeper (Plant) - Elephant creeper (Entada pursaetha)
  • Leaf - Raphia vinifera (30-50 ft)


  • Alga - Macrocystis macrocarpa (Brown alga, Kelp 60 m)
  • Amphibian - Cryptobranchus
  • Antherozoid - Cycas circinalis
  • Archegonium - Bryophyte (Moss)
  • Biome (richest in terms of plant species) - Tropical rainforest
  • Bird sanctuary - Bharatpur
  • Class (of plantae) - Angiosperms
  • Coral reef in world - Great barrier reef of North East Coast of Australia (2 × 103 kms.)
  • Exocrine gland - Liver
  • Flower - Rafflesia arnoldii
  • Largest Forest area in India - Madhya Pradesh
  • Number of Animal chromosomes - Aulacantha (Radiolarian; 2n=1600)
  • Number of Plant chromosomes - Ophioglossum (pteridophyte,  Adler's tongue, 2n=1262)
  • Plant cell - Acetabularia (green alga)
  • Pollen grain in Angiosperms - Mirabilis
  • Primate - Gorilla
  • Phylum (of Animals) - Arthropoda


  • Anti Leprosy Day - 30th January
  • Blood Donation Day - 1st October
  • Doctor's Day - 1st July
  • Human Rights Day - 10th December (To commemorate the  death of Alfred Nobel)
  • International Day of Biodiversity - 29th December
  • International Thalassaemia day & World - 8th May
  • Red. Cross Day - 8th May
  • Kisan Divas (National Farmer's Day) - 23rd December
  • National Pollution Prevention Day - 2nd December
  • Van Mahotsava (Festival of Tree Plantation) - 1st week of February and July
  • Vigyan Divas (National Science day) - 28 February
  • World AIDS day - 1st December
  • World Conservation Day - 3rd December
  • World Earth day - 22nd April
  • World Environment Day - 5th June
  • World Forest Day - 21st March
  • World Health Day - 7th April
  • World Literacy Day - 8th September
  • World Ozone Day - 16th September
  • World Population Day - 11th July
  • World Wildlife Week - 1st Monday of October


  • Largest artery - Abdominal aorta
  • Largest bone - Femur
  • Largest heterocrine organ - Alimentary canal
  • Largest endocrine gland - Thyroid
  • Largest gland - Liver
  • Largest salivary gland - Parotid gland
  • Largest vein - Inferior Vena cava
  • Least regenerative capacity - Brain
  • Longest cell in the body - Neuron
  • Longest cranial nerve - Vagus
  • Longest nerve of the body - Sciatic
  • Muscles : Number - 639
Smallest muscle - Stapedius
Largest muscle - Gluteus maximus
Longest muscle - Sartorius

  • Number of cranial nerves - 12 pairs
  • Number of spinal nerves - 31 pairs
  • Smallest cranial nerve - Abducens
  • Smallest bone - Stapes (2.6 – 3.4 mm)
  • Smallest endocrine gland - Pituitary
  • Speed of Sneezing - 60-100 miles/hour
  • Spinal cord :  Weight - 35g. Length - 42-45 cm

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The Living World | Biology Notes for NEET/AIIMS/JIPMER
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