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Slide 1

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Conditions for life on
earth…read more

Slide 2

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The availability of liquid water
Water is essential for all life
Physiological solvent
Chemical reactions take place in solution
needed for nutrient uptake
transport of substances
dilution of waste
Moving nutrients within an organism
Removing waste from an organism
The anomalous expansion on freezing (ice floats) prevents many
water bodies from freezing solid.
Floating ice insulates
prevents water freezing solid (for survival of organisms
albedo controls climate
Ice layer creates a habitat e.g. north pole. The high specific heat
capacity of water moderates temperature change.
This means that water temperature is more stable. It doesn't…read more

Slide 3

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Temperature range
For liquid water
Enzyme function…read more

Slide 4

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Suitable ambient gases
Carbon dioxide (for photosynthesis) and
nitrogen (proteins) in the pre-life atmosphere
(oxygen was not abundant).…read more

Slide 5

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Sunlight for photosynthesis
Sun a source of energy for the water cycle…read more

Slide 6

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How the presence of life on Earth has
brought about environmental change
Atmospheric oxygen
O2 given out by photosynthetic organisms.
A `new' gas
The first pollutant
O2 interacts with UV light making it split. The single O atoms react
with more O2 making O3 ­ ozone.
Atmospheric carbon dioxide
Reduction of CO2 levels and the importance of this in maintaining
global temperatures as the sun has become brighter.
Why would life reduce CO2 levels?
Organisms able to photosynthesise
Take in CO2 and give out O2
How would a reduction of CO2 affect the temp?
Reduce it
Lucky as the Sun was getting brighter and hotter.…read more


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