Scientists in NCERT Biology (Class 11 & 12) | Download PDF


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1. The Living World

Carl Linnaeus

· Wrote the book Systema Naturae.
· Proposed Binomial nomenclature.

2. Biological Classification


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)


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.


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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.


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.


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.


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


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


Conducted experiments on the rocky sea coasts of Scotland, using 2 barnacle species, Balanus & Chthamalus. It is known as Connell’s field experiments.


Proposed Competitive Exclusion Principle.


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.
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