XII |
EVOLUTION
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QUESTIONS |
NOTES |
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Age of
universe: 20 bn yrs ago
Age of
Earth: 4.5 bn yrs ago
Life
appeared: 4 bn yrs ago
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Universe m/o clusters of galaxy. Galaxy m/o clusters of stars,
clouds of gases & dust.
BIG BANG THEORY: explains origin of
universe.
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Composition
of Earth: Water vapour, methane, CO2, NH3 (frm molten
mass on Earth’s surface)
No atmosphere
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Processes on Earth post big bang led to formation
of CO2, water etc.
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Theories
of Origin of Life:
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Panspermia: Life came from outer space as ‘spores’
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Spontaneous generation: Life originated from
decaying matter
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Life comes from pre-existing life – Louis Pasteur
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Abiological Origin of life: Oparin &
Haldane
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Exp demo of above: Miller
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Define Biogenesis
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Biogenesis/
Chemical Evolution:
 Inorganic
molecules  Non-living organic molecules s/a proteins,
RNA etc. Life
Conditions required: High temp, Volcanic
storms, reducing atmosphere containing CH4, NH3 etc
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Miller’s
exp:
Flask with:
CH4, NH3, H2 (red. Atm)
Water vapour
Electric
Spark (high temp – 800°C)
Result: Amino acids formed
Further Proof:
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Others obtained sugars, pigments, fats, N
bases in similar exp
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Meteorite content reveals similar material
from other places in space
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