NEET BIOLOGY Important Dates and Years (2).pdf

biology_at_ease Biology at Ease
Biology at Ease
Biology at Ease
NEET BIOLOGY Important Dates and Years Class XII
Date/Year Event
➢ 1951 Family Planning
➢ 1971 Medical Termination of Pregnancy (MTP)
➢ 1856 – 1863 Gregor Mendel Experiments
➢ 1865 Mendel published his work on inheritance of characters
(but remained unrecognized till 1900)
➢ 1900 Rediscovery of Mendel’s results on inheritance of characters
by de Vries, Correns, and von Tschermak
➢ 1902 Walter Sutton and Theodore Boveri proposed Chromosomal
theory of inheritance
➢ 1891 Henking traced a specific nuclear structure all through
spermatogenesis to understand mechanism of sex-
determination

Biology at Ease
Biology at Ease
Date/Year Event
➢ 1866 Langdon described Down’s syndrome
➢ 1869 Friedrich Meischer identified DNA as an acidic substance in
nucleus and named it “Nuclein”
➢ 1953 James Watson and Francis Crick proposed double helix
structure of DNA
➢ 1928 Transforming principle by Fredrick Griffith
➢ 1933 – 44 Biochemical characterization of Transforming principle by
Oswald Avery, Colin MacLeod and Maclyn McCarty
➢ 1952 Unequivocal proof that DNA is genetic material by Alfred
Hershey and Martha Chase
➢ 1953 Watson and Crick proposed semiconservative DNA replication

Biology at Ease
Biology at Ease
Date/Year Event
➢ 1958 Experimental proof for semiconservative DNA
replication by Matthew Meselson and Franklin Stahl
➢ 1990 – 2003 Human Genome Project (HGP)
➢ May, 2006 Sequence of Chromosome-1 was completed
➢ 20 billion years Age of universe
➢ 4.5 billion years Age of earth.
➢ 4 billion years back (500
million years after
formation of earth)
Life appeared on earth
➢ 1953 Miller Urey experiment
➢ 3 billion years back The first non-cellular life originated
➢ 2000 million years ago First cellular form of life appeared

Biology at Ease
Biology at Ease
Date/Year Event
➢ 1920 The phenomenon of natural selection observed after
industrialization in England
➢ 500 mya Invertebrates were formed and active
➢ 350 mya Jawless fish evolved
➢ 320 mya Sea weeds and few plants existed
➢ 350 mya Fish with stout and strong fins could move on land and
go back to water
➢ 1938 Coelencanth was caught in South Africa
➢ 200 mya Some of the land reptiles (Ichthyosaurs) went back into
water to evolve into fish like reptiles
➢ About 65 mya Dinosaurs suddenly disappeared from earth
➢ 15 mya Origin of Dryopithecus and Ramapithecus

Biology at Ease
Biology at Ease
Date/Year Event
➢ 3 – 4 mya Australopithecus
➢ 2 mya Homo habilis
➢ 1.5 mya Homo erectus (Java man)
➢ 100,000 – 40,000
years ago
Homo sapiens neanderthalesis (Neanderthal man)
➢ 75,000 – 10,000 Homo sapiens (Modern man)
➢ 1981 AIDS was first reported
➢ Mid 1960s Green revolution
➢ 1960 – 2000 ▪ Wheat production increased from 11 million tons to 75 million tons
▪ Rice production increased from 35 million to 89.5 million tons
➢ 1963 Semi-dwarf varieties of wheat – Sonalika and Kalyan Sona were
introduced in India

Biology at Ease
Biology at Ease
Date/Year Event
➢ 2000 Maize hybrids having twice the amount of amino acids, lysine and
tryptophan were developed
➢ 1950s Totipotency
➢ 1972 Construction of first Recombinant DNA by Stanley Cohen and
Herbert Boyer
➢ 1963 Two enzymes responsible for restricting the growth of
bacteriophage in Escherichia coli were isolated
➢ 1990 First gene therapy given to a four year old girl with ADA deficiency
➢ 1997 The first transgenic cow, Rosie, produced human protein-enriched
milk (2.5 grams per litre)
➢ 1920s The prickly pear cactus introduced into Australia
➢ 1992 “The Earth summit” – Rio de Janeiro

Biology at Ease
Biology at Ease
Date/Year Event
➢ 1986 Environment Protection Act
➢ 1981 Air (Prevention and Control of Pollution) Act came into force
➢ 1987 Air (Prevention and Control of Pollution) Act was amended to
include noise as an air pollutant
➢ 1990s Delhi ranked 4th among the 41 most polluted cities in the world
➢ (by the end of) 2002 All the buses of Delhi were converted to run on CNG
➢ 1997 – 2005 A substantial fall in CO2 and SO2 levels has been found in Delhi
➢ 1974 Water (Prevention and Control of Pollution) Act
➢ 1974 Chipko Movement
➢ 1980s Joint Forest Management (JFM)
➢ 1987 Montreal Protocol signed at Canada
➢ 1989 Montreal protocol (effective)

Biology at Ease
Biology at Ease
NEET BIOLOGY Important Dates and Years Class XI
Date/Year Event
➢ 1969 Five Kingdom Classification by R.H. Whittaker
➢ 1892 Virus was named and discovered by Dimitri Ivanowsky
➢ 1935 W.M. Stanley showed virus could be crystallized
➢ 1971 T.O. Diener discovered viroids
➢ 1838 Matthias Schleiden examined a large number of plants and
observed that all plants are composed of different kinds of cell
which form the tissues of the plant
➢ 1839 Theodore Schwann studied different types of animal cells and
reported that cells had a thin outer layer which is today known
as ‘plasma membrane’
➢ 1855 Rudolf Virchow explained that cells arises from pre-existing
cells (Omnis cellula-e cellula)
➢ 1898 Camillo Golgi discovered golgi apparatus

Biology at Ease
Biology at Ease
NEET BIOLOGY Important Dates and Years Class XI
Date/Year Event
➢ 1860 Julius von Sachs discovered hydroponics
➢ 1770 Joseph Presley revealed essential role of air in the growth of
green plant
➢ 1774 Joseph Presley discovered oxygen
➢ 1854 Julius von Sachs provided evidence for the production of
glucose when plants grow
➢ 1905 Blakman’s law of limiting factor
➢ 1926 Gibbrellic acid was discovered by E. Kurosawa
➢ 1955 Miller et al. identified and crystallized cytokinins
➢ Mid 1960s Inhibitor-B, abscission II and dormin were reported
➢ 1910 H.H cousins discovered ethylene

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