Saturday, 9 February 2019

Key Points: Evolution (Big Bang & Origin) Part 1


 

XII

         

EVOLUTION

QUESTIONS

NOTES


Age of universe: 20 bn yrs ago
Age of Earth: 4.5 bn yrs ago
Life appeared: 4 bn yrs ago

Universe m/o clusters of galaxy. Galaxy m/o clusters of stars, clouds of gases & dust.
BIG BANG THEORY: explains origin of universe.

Composition of Earth: Water vapour, methane, CO2, NH3 (frm molten mass on Earth’s surface)
No atmosphere

Processes on Earth post big bang led to formation of CO2, water etc.

Theories of Origin of Life:
·       Panspermia: Life came from outer space as ‘spores’
·       Spontaneous generation: Life originated from decaying matter
·       Life comes from pre-existing life – Louis Pasteur
·       Abiological Origin of life: Oparin & Haldane
·       Exp demo of above: Miller
Define Biogenesis
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

Miller’s exp:
Flask with: CH4, NH3, H2 (red. Atm)
                     Water vapour
                     Electric Spark (high temp – 800°C)
Result: Amino acids formed
Further Proof:
·       Others obtained sugars, pigments, fats, N bases in similar exp
·       Meteorite content reveals similar material from other places in space



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