SCIENTISTS IN NCERT BIOLOGY:
CLASS 11
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1. The Living World
Carl Linnaeus
· Wrote the book Systema Naturae.
· Proposed Binomial nomenclature.
2. Biological Classification
Aristotle
Classified plants to trees, shrubs & herbs and animals into 2 groups- those with red blood & without red blood.
Carl Linnaeus
Proposed Two Kingdom classification- Plantae & Animalia.
R.H. Whittaker
Proposed Five Kingdom Classification.
Dmitri Ivanowsky
Discovered virus. He recognized certain microbes that cause mosaic disease of tobacco.
M.W. Beijerinek
· Demonstrated that the extract of the infected tobacco plants cause infection in healthy plants.
· He named new pathogen as virus and the fluid as Contagium vivum fluidum (infectious living fluid).
W.M. Stanley
Showed that viruses could be crystallized and crystals consist largely of proteins.
T.O. Diener
· Discovered viroid.
· He found that it caused potato spindle tuber disease.
3. Plant Kingdom
Carl Linnaeus
Proposed Artificial system of classification based on the androecium structure.
George Bentham & Joseph Dalton Hooker
Proposed Natural classification systems of Classification for flowering plants
4. Cell the Unit of Life
Robert Hooke
Discovered cell.
Anton Von Leeuwenhoek
First observed and described a live cell.
Matthias Schleiden
Observed that all plants are composed of cells.
Theodore Schwann
· Found that cells have a plasma membrane.
· Found that plant cells have cell wall.
· He proposed a hypothesis that animals and plants are composed of cells and products of cells.
· Schleiden & Schwann formulated the cell theory.
Rudolf Virchow
First explained that cells divide and new cells are formed from pre-existing cells (Omnis cellula-e cellula). He modified the cell theory.
Singer & Nicolson
Proposed Fluid mosaic model of cell membrane.
Camillo Golgi
First observed Golgi apparatus.
George Palade
First observed ribosome.
Robert Brown
Discovered cell Nucleus.
5. Biomolecules
Watson & Crick
Double helix model of DNA
6. Mineral Nutrition (Deleted Chapter)
Julius von Sachs
Demonstrated the technique of hydroponics (growing plants in a defined nutrient solution without soil).
7. Photosynthesis
Joseph Priestley
· Performed bell jar experiments to prove the role of air in the growth of green plants.
· Discovered oxygen.
Jan Ingenhousz
· Conducted the same experiment of Priestley by placing in darkness and sunlight. He showed that sunlight is essential to the plant for purifying the air fouled by burning candles or animals.
· He showed that only the green part of plants releases O2.
Julius von Sachs
He proved that
· Glucose is produced when plants grow and it is usually stored as starch.
· Chlorophyll is located in special bodies (chloroplasts).
· Glucose is made in the green parts of plants.
T.W Engelmann
First described action spectrum of photosynthesis using a prism to split light and illuminate a green alga, Cladophora, suspended in aerobic bacteria.
Cornelius van Niel
Studied purple and green bacteria, demonstrating that photosynthesis is a light-dependent reaction where hydrogen reduces CO2 to carbohydrates. He inferred that the O2 evolved by plants comes from H2O, not CO2.
Hatch and Slack
First described C4 pathway (Hatch & Slack pathway)
Blackman
Proposed Blackman’s Law of Limiting Factors
8. Respiration in Plants
Gustav Embden, Otto Meyerhof & J. Parnas
Proposed the scheme of glycolysis (EMP pathway).
Hans Krebs
First elucidated TCA cycle (Krebs’ cycle).
9. Plant Growth & Development
Charles Darwin & his son Francis Darwin
Observed that the coleoptiles of canary grass grow towards the light source (phototropism). The tip of coleoptile causes the bending of the entire coleoptile.
F.W. Went
Isolated Auxin from tips of coleoptiles of oat seedlings.
E. Kurosawa
He exposed a rice seedling to sterile filtrates of Gibberalla fujikuroi. It showed the symptoms of ‘bakane’ disease. The active substances were later identified as gibberellic acid.
F. Skoog & Miller
· Discovered Cytokinins.
· Observed that from the internodal segments of tobacco stems, the callus proliferated only if the nutrients medium was supplemented with extracts of vascular tissues/ yeast extract/ coconut milk/ DNA.
· Later they identified and crystallized the active substance and termed as kinetin.
H.H Cousins
Found that ripened oranges released a volatile substance that hastened the ripening of stored bananas. This substance was ethylene.
SCIENTISTS IN NCERT BIOLOGY:
CLASS 12
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1. Principles of Inheritance and Variation
Gregor Mendel
· Father of Genetics.
· He conducted hybridization experiments on garden peas (Pisum sativum)
· Proposed Laws of Inheritance.
de Vries, Correns & von Tschermak
Independently rediscovered Mendel’s results.
Walter Sutton & Theodore Boveri
· Proposed Chromosomal Theory of Inheritance.
· Sutton united chromosomal segregation with Mendelian principles and called it the chromosomal theory of inheritance.
Thomas Hunt Morgan
· Proved chromosomal theory of inheritance using fruit flies (Drosophila melanogaster).
· Coined the terms linkage and recombination.
· He studied about sex-linked genes in Drosophila.
Alfred Sturtevant
He mapped gene positions on chromosomes using recombination frequencies.
Henking
Discovered X chromosome. He called it X body.
Langdon Down
First described Down’s syndrome.
2. Molecular Basis of Inheritance
Friedrich Miescher
Identified DNA and named it Nuclein.
James Watson & Francis Crick
· Proposed double helix model of DNA.
· Proposed Semi-conservative model of DNA replication.
Maurice Wilkins & Rosalind Franklin
Produced X-ray diffraction data of DNA.
Erwin Chargaff
Proposed a rule which states that in DNA, the ratio of A to T and the ratio of G to C are equal.
Francis Crick
· Proposed Central dogma of Molecular Biology.
· Postulated about an adapter molecule that can read the code and to link with amino acids.
Frederick Griffith
Conducted Transforming Principle Experiment using Streptococcus pneumoniae and mice.
Oswald Avery, Colin MacLeod & Maclyn McCarty
Conducted experiment for Biochemical characterization of transforming principle to determine the biochemical nature of ‘transforming principle’ in Griffith’s experiment.
Alfred Hershey & Martha Chase
Conducted Blender Experiment to prove DNA is the genetic material.
Matthew Meselson & Franklin Stahl
Experimentally proved Semi-conservative model.
Taylor
Performed similar experiments on Vicia faba (faba beans) using radioactive thymidine to detect distribution of newly synthesized DNA in the chromosomes. It proved that the DNA in chromosomes also replicate semi-conservatively.
George Gamow
Suggested that for coding 20 amino acids, the code should be made up of 3 nucleotides. Thus, there are 64 codons.
Har Gobind Khorana
Developed a chemical method in synthesizing RNA molecules with defined combinations of bases (homopolymers & copolymers).
Marshall Nirenberg
Developed cell-free system for protein synthesis.
Francois Jacob & Jacque Monod
First elucidated Lac operon (an operon that controls lactose metabolism in bacteria).
Frederick Sanger
· Developed a method that is used to sequence DNA fragments in automated DNA sequencers
· He has also developed method for sequencing of amino acids in proteins.
Alec Jeffreys
Developed DNA fingerprinting (DNA profiling)
3. Evolution
Louis Pasteur
Disproved Theory of spontaneous generation (Abiogenesis). He demonstrated that life comes only from pre-existing life.
Oparin & Haldane
Proposed Theory of chemical evolution.
S.L Miller
Experimentally proved theory of chemical evolution.
Ernst Haeckel
Proposed Embryological evidences of evolution.
Karl Ernst von Baer
Rejected Embryological evidences of evolution.
Lamarck
Proposed Theory of Inheritance of acquired characters (Lamarckism).
Charles Darwin
Proposed Theory of Natural selection (Darwinism).
Alfred Wallace
Proposed Natural selection (similar conclusions of Darwin).
Thomas Malthus
Studied on populations. It influenced Darwin.
Hugo de Vries
Proposed Mutation Theory of evolution.
Hardy & Weinberg
Proposed Hardy-Weinberg principle about genetic equilibrium.
4. Human Health and Diseases
Hippocrates
Proposed Good humour hypothesis.
William Harvey
Disproved Good humour hypothesis.
5. Microbes in Human Welfare
Alexander Fleming
Discovered the first antibiotic Penicillin from a mould Penicillium notatum.
Earnest Chain and Howard Florey
Established full potential of Penicillin as an effective antibiotic.
Fleming, Chain & Florey were awarded Nobel Prize (1945).
6. Biotechnology-Principles and Processes
Stanley Cohen & Herbert Boyer
Produced first recombinant DNA (rDNA).
7. Organisms and Populations
Connell
Conducted experiments on the rocky sea coasts of Scotland, using 2 barnacle species, Balanus & Chthamalus. It is known as Connell’s field experiments.
Gause
Proposed Competitive Exclusion Principle.
MacArthur
Showed that five closely related species of warblers living on a tree could avoid competition and co-exist due to behavioural differences in their foraging activities.
8. Ecosystem
Robert Costanza
Put price tags on nature’s life-support services.
>9. Biodiversity and Conservation
Edward Wilson
Popularized the term ‘biodiversity’.
Robert May
Proposed a Global estimate of species diversity on earth. According to this about 7 million species would have on earth.
Alexander von Humboldt
His studies in South American jungles showed that species richness increases with the size of the explored area, but only up to a limit.
David Tilman
According to him, plots with more species shows less year-to-year variation in total biomass.
Paul Ehrlich
Proposed Rivet popper hypothesis. It is an analogy used to understand the importance of biodiversity.
10. Environmental Issues (Deleted Chapter)
Ahmed Khan (a plastic sack manufacturer in Bangalore)
Developed Polyblend (a fine powder of recycled modified plastic. It is mixed with the bitumen and is used to lay roads).
Ramesh Chandra Dagar (a farmer in Sonipat, Haryana)
He included bee-keeping, dairy management, water harvesting, composting & agriculture in Integrated Organic Farming.