Earth History

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The first living organisms gained their energy by a fermentation of the organic soup

C6H12O6  Alcohol + CO2 + Energy

However there was only a limited amount of organic nutrients in the primeval soup and to sustain life. ( First Famine ).

A new efficient Energy Source was required.

Slide 19

Role of Blue Green Algae

Blue Green Algae & Photosynthetic Bacteria developed to use water as a hydrogen donor and produced dioxygen as a by product.

Photosynthesis

nCO2 + nH2O  ( CH2O)n + nO2

6CO2 + 6H20  C6H12O6 + 6O2

Slide 20

Decline of Anaerobic Bacteria

Problem for Anaerobic Organisms

Evidence of the appearance of Oxygen is indicated in the (Red Layers) of the Grand Canyon. O2 is believed to have entered the atmosphere about 1.8 Billion years ago

Fe2+ and oxygen reactions may have delayed entry of oxygen into the atmosphere.

Slide 21

Oxygen Rich Planet

Oxygen Rich Planet

The build up of Oxygen in the atmosphere led to the formation of the

Ozone Layer at 15 to 60 km above the earth.

Ozone O3 absorbs harmful UV light and this allowed organisms to colonize the Water/Land/ Atmosphere interface.

Slide 22

Oxygen Rich Planet

Respiration utilized the photosynthetic Compounds (Sugar ) to produce Energy

(CH2O)n + nO2  nCO2 + H2O + E

This process was 18 times more efficient than the fermentation process .

But oxygen can damage cellular material

Slide 23

The trouble with oxygen

The ultilization of oxygen in producing energy resulted in emergence Eukarotic cells which contained a nucleus which protected cellular material prone to oxidation.

( DNA)

Slide 24

The present atmosphere

The present atmosphere has arisen from

(1) The distance of the earth from the sun

(2) Nature of the earth’s composition

(3) The rise of life.

Slide 25

Distance from the Sun

The distance from the Sun determines the kinetic energy (KE) of the molecules in the atmosphere due to the Sun’s heat and the molecule’s velocity.

KE = 1/2 mv2 & KE = 3/2kT

Where m is the mass of the molecule (Mr /NA)

k is the Boltzmann constant (R/NA)

( Earth  !50 x 106km)

Transit of Venus

Capt Cook to within 2% of the value 1788

Slide 26

Influence of Earth’s Mass