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ORIGIN OF LIFE
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Origin of universe
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Big-bang Theory
▢ Proposed by: Abbe Lemaitre (1931)
▢ Age: Approximately 10^10 years
▢ Description:
❖ Current universe: About 20 billion years old with huge clusters of galaxies
❖ Galaxies: Contain stars and clouds of gas and dust
❖ Event: Singular huge explosion unimaginable in physical terms
❖ Aftermath:
◉ Expansion: Universe expanded causing temperature to decrease
◉ Element formation: Hydrogen and Helium formed later
◉ Galaxy formation: Gases condensed under gravitation to form present-day galaxies
▢ Solar system formation: Formed about 4.6 billion years back in the milky way galaxy
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Origin of earth
📝
Formation
About 4.6 billion years back in the milky way galaxy
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Early conditions
▢ Atmosphere: Initially absent
▢ Surface composition: Covered by Methane(CH4), Ammonia(NH3), Water(H2O) and Carbon dioxide(CO2) released from molten mass
▢ UV radiation effects:
❖ Water breakdown: UV rays split water into Hydrogen(H2) and Oxygen(O2)
❖ Hydrogen: Lighter Hydrogen escaped
❖ Oxygen reactions: Combined with Methane (CH4) and Ammonia (NH3) to form Water (H2O), CO2 and others
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Early events
▢ Bombardment period: Subjected to heavy bombardment with large comets and meteorites
▢ Ocean vaporization: Heat from impacts periodically vaporized oceans
▢ Life appearance: Appeared 0.5 billion years after Earth's formation (~4 billion years ago)
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Introduction
▢ Timeline: Life appeared 0.5 billion years after Earth's formation (~4 billion years ago)
▢ Significance: Considered a unique event in the history of universe
▢ Early Earth: Could not support life when first formed
▢ Life organization: Organized from non-living materials between Earth's formation and first fossils
▢ Nature of life: Chemical phenomenon with chemical origin
▢ Research: Since 1950, full-time research on origin of life studies in several laboratories worldwide
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Theories on origin of life
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Special creation theory
▢ Support: Most of the world's major religions and civilizations
▢ Religious texts:
❖ Bible and Hindu philosophy: God created all living organisms
▢ Key proponents:
❖ Father Suarez: Spanish priest, greatest supporter of special creation theory
❖ Archbishop Ussher: Claimed God created the world in October 4,004 BC (specific timeline provided)
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Abiogenesis/Spontaneous generation
▢ Historical belief: Ancient Chinese, Babylonians and Egyptians believed life could arise spontaneously from non-living material
▢ Examples:
❖ Frogs: From damp Earth
❖ Mice: From putrefied matter
❖ Insects: From dew
❖ Maggots: From decaying meat
▢ Van Helmont's experiment: Claimed young mice could arise from wheat grains in a dark cupboard with a moist dirty shirt (1557-1644)
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Biogenesis (Life from life)
▢ Opponents of spontaneous generation:
- Francesco Redi (1668)
- Abbe Lazzaro Spallanzani (1767)
- Louis Pasteur (1867)
▢ Key experiments:
❖ Redi experiment: Disproved spontaneous generation of flies from rotting meat
❖ Spallanzani experiment:
◉ Method: Sterilized nutritive broth by boiling meat in sealed flasks
◉ Conclusion: Air carried microorganisms
❖ Pasteur's swan-neck experiment:
◉ Method: Used flasks that allowed air but not microorganisms
◉ Conclusions:
- Demonstrated biogenesis
- Finally disproved spontaneous generation (1861)
- Didn't explain first life form
- Discovered role of bacteria in fermentation and anaerobic bacteria
◉ Contributions:
- Germ theory of disease
- Principle of sterilization (Pasteurization)
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Cosmozoic theory/Spore theory
▢ Proponents:
- Richter (1865)
- Arrhenius (1908)
▢ Concept: Life transferred between planets as spores
▢ Modern support: Some astronomers believe primitive life came via meteorites (Panspermia)
▢ Evidence cited:
- UFO sightings
- Cave drawings of rocket-like objects
- 1996 NASA discovery of possible bacterial remains in Martian rock
📝
Catastrophism theory
▢ Proposed by: Georges Cuvier (1796)
▢ Concept: Simultaneous extinction and creation of life from inorganic material via natural cataclysms
📝
Oparin-Haldane theory
▢ Proponents:
- Alexander Oparin (1924, expanded 1936)
- J.B.S. Haldane (1929)
▢ Key concepts:
❖ Primitive atmosphere: Reducing atmosphere without free oxygen
❖ Modern atmosphere:
◉ Composition:
- 78% molecular nitrogen
- 21% free oxygen (from photosynthesis)
- 1% argon
- 0.03% carbon dioxide
◉ Nature: Strongly oxidizing
❖ Essential condition: Presence of water
❖ Energy sources:
- Solar radiation
- Lightning
- Volcanic ash
❖ Chemical evolution:
◉ First compounds: Methane, Ethylene, Acetylene (hydrocarbons)
◉ Primordial soup: Organic compounds accumulated in oceans (Haldane's 'hot dilute soup')
◉ Polymerization: Formed proteins, carbohydrates and fats
▢ Experimental support:
❖ Miller-Urey experiment (1953):
◉ Apparatus: Spark discharge apparatus
◉ Gases used: Methane(CH4), Ammonia(NH3), Hydrogen(H2) (2:1:2) and Water(H2O)
◉ Results:
- Synthesized 15 amino acids including Glycine, Alanine, Valine, Proline, Aspartic acid
- Demonstrated formation of organic monomers
❖ Melvin-Calvin experiment (1951):
◉ Method: Irradiated CO2 and H2O in cyclotron
◉ Products:
- Formic acid
- Succinic acid
- Oxalic acids
◉ Recognition: Nobel Prize (1961)
▢ Macromolecule evolution:
❖ Polymer formation: Through dehydration synthesis
❖ Hypotheses:
◉ RNA-first hypothesis:
◈ Concept: RNA could perform both genetic and enzymatic functions
◈ Evidence:
- Ribozymes (catalytic RNA discovered by Thomas Cech and Sidney Altman, Nobel 1989)
- Some viruses have RNA genes
◈ Implication: Early 'RNA world'
◉ Protein-first hypothesis:
◈ Proponent: Sidney Fox
◈ Findings:
- Amino acids polymerize abiotically to form proteinoids
- Proteinoids form microspheres with cellular characteristics
◉ Cairns-Smith's hypothesis:
◈ Concept: Clay facilitated simultaneous polymerization of proteins and nucleic acids
◈ Mechanism: Clay attracts organic molecules and contains catalytic metals (iron, zinc)
▢ Protocell evolution:
❖ Definition: Structure with lipid-protein membrane capable of energy metabolism
❖ Formation theories:
◉ Fox's microspheres: Lipids associate with proteinoids forming membranes
◉ Oparin's coacervates: Concentrated macromolecules forming complex units that absorbed organic substances
❖ Characteristics: Anaerobic chemoheterotrophs
▢ First cells:
❖ Features:
- Membrane boundary
- Heterotrophic fermenters with enzyme activity
- Capable of reproduction
❖ Oldest fossils: 3.5 billion years old, resembling heterotrophic bacteria
▢ Prokaryote evolution:
❖ Timeline: Evolved before eukaryotes
❖ Early types:
- Chemoheterotrophs (fermentation)
- Anaerobic chemoautotrophs
- Photosynthetic bacteria (initially only photosystem I)
❖ Key developments:
- Cyanobacteria developed oxygenic photosynthesis (two photosystems)
- Archaeospheroides barbertonesis (oldest fossil, 3.2 billion years)
- Oxygen as first major pollutant
❖ Genetic mechanisms:
- Binary fission (limited variability)
- Mutations as primary source of variation
▢ Eukaryotic cell origin:
❖ Oldest fossils: 1.5 billion years old
❖ Energy metabolism: Aerobic cellular respiration
❖ Classification history: Haeckel (1868) proposed kingdoms Monera (prokaryotes) and Protista (unicellular eukaryotes)
❖ Evolutionary significance: Led to protists, fungi, plants and animals
▢ Extraterrestrial life:
❖ Potential location: Mars (no conclusive evidence found)
Q1.
Heredity and variation was postulated by
📅MOE 2008
Q2.
Charles Darwin's theory of evolution is based on
📅MOE 2064
Q3.
Most accepted theory for origin of life is
📅MOE 2063
Q4.
Organs which have same basic structure and origin but differ in function are called
📅MOE 2062•MOE 2055
Q5.
Wings of birds and insects are
📅MOE 2061
Q6.
Fins of fishes and flipper of whale are
📅MOE 2003
Q7.
Inheritance of acquired character is given by the concept of
📅MOE 2005•MOE 2054
Q8.
Theory of continuity of germ plasm was proposed by
📅MOE 2033
Q9.
Postulation of the theory of natural selection published in 1858 was given by
📅MOE 2054
Q10.
Organs having similar function but different structure or origin are called
📅IOM 2007
Q11.
The mutation theory of evolution was proposed by
📅IOM 2004
Q12.
Which of the following is a living fossil?
📅IOM 2024
Q13.
Which of the following is a connecting link between animal and plant kingdom?
📅IOM 2003
Q14.
Founder of palaeontology is
📅IOM 2003
Q15.
The main drawback of Darwin's theory is
📅IOM 1995
Q16.
Earlier organisms were
📅BPKIHS 2002
Q17.
Three stages of evolution was given by
📅BPKIHS 2002
Q18.
The sun, earth and stars are reformed from
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Q19.
Correct sequence among the following is
📅BPKIHS 2004
Q20.
Coacervates are clusters of
📅BPKIHS 2005
Q21.
The organisms which depended on organic molecules present in primitive ocean were referred as
📅BPKIHS 2005
Q22.
The study of fossils is called
📅MOE 2062
Q23.
Wings of mosquito, bat and sparrow exhibit the phenomenon called
📅MOE 2062
Q24.
Phylogeny represents
📅MOE 2062
Q25.
Which is not a universal character of protoplasm?
📅MOE 2003
Q26.
Protoplasm is
📅MOE 2003
Q27.
Peripatus is a connecting link between
📅MOE 2002
Q28.
According to neo-Darwinism, evolution is due to
📅IE 2009
Q29.
Two sets of muscles responsible for ear movement are
📅IE 2002
Q30.
During vertebrate brain evolution, the part showing greatest evolution by acquiring large size is
📅IE 2002
Q31.
The morphological study based on phylogenetic characters and homologous development is
📅IE 2002
Q32.
The study of evidence of origin of evolution and its branches according to phylogenetic tree is called
📅IE 2002
Q33.
Fossils are mostly found in
📅IE 2003
Q34.
Natural selection acts directly on
📅IE 2004
Q35.
Evolution of photosynthetic ability resulted in division of living world into
📅IE 2008
Q36.
Allopatric speciation is caused by
Q37.
Connecting link between arthropoda and annelida is
📅BPKIHS 2014
Q38.
Who gave the principle of biogenetic law?
📅BPKIHS 2014
Q39.
During evolution of earth, the first compound formed was
📅BPKIHS 2014
Q40.
Which gas was most abundant during earth formation?
📅BPKIHS 2014
Q41.
Sudden appearance of tail in a small baby is an example of
📅BPKIHS 2015
Q42.
Connecting link between animal and plant is
📅BPKIHS 2016
Q43.
Which of the following is closest to man?
📅BPKIHS 2014
Q44.
The main strong evidence for evolution is
📅BPKIHS 2014
Q45.
The most basic substance of origin of life is
📅BPKIHS 2014
Q46.
Harold C. Urey's laboratory experiment found large number of complex organic compounds, among which the essentials of life were
📅MOE 2014•MOE 2013
Q47.
Stout-running forelegs of horse and forearms of human used for catching are
📅MOE 2014
Q48.
Canine teeth in man are
📅MOE 2014
Q49.
Gill slits present in embryonic stage of vertebrates represent
📅MOE 2014
Q50.
The word coacervate was first used by
📅MOE 2012
Q51.
Modern human beings were originated from
📅MOE 2012
Q52.
Origin of species was postulated by
📅MOE 2062
Q53.
Which of the following were first formed?
📅KU 2015
Q54.
The concept of survival of the fittest was advanced by
📅KU 2015
Q55.
The term Homo sapiens was coined by
📅KU 2015
Q56.
Recapitulation theory means that
📅KU 2014
Q57.
Darwin's statement 'survival of the fittest' means that
📅KU 2012
Q58.
The process of inheritance of character in living beings is called
📅KU 2011
Q59.
The principle of inheritance of acquired characters was given by
📅KU 2011