3.  Water is essential for all life
◦ Physiological solvent
 Chemical reactions take place in solution
 needed for nutrient uptake
 transport of substances
 dilution of waste
◦ Transport
 Moving nutrients within an organism
 Removing waste from an organism
◦ Coolant
 Sweating
 Bathing to cool

4. ◦ 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
beneath)
 albedo controls climate
 Ice layer creates a habitat e.g. north pole.

5. ◦ The high specific heat capacity of water moderates
temperature change.
 This means that water temperature is more stable. It
doesn’t get too cold too quickly and doesn’t get too
hot too quickly.

6. ◦ Water provides aquatic habitats.
 Is transparent too which allows light to penetrate for water
plants. Why is this important?
 photosynthesis
 It also allows predators to see prey and prey to see
predators.

7. ◦ Most areas of planet is above 0oC- allows liquid
water
◦ Enzymes need liquid water as solvent and denature
at high temperatures – most organisms between 0 –
40oC, some organisms can stand up to 80oC – the
earth is in this range

8. ◦ there are suitable gases for developing and using
life :
◦ Carbon dioxide (for photosynthesis) and nitrogen
(proteins) in the pre-life atmosphere (oxygen was
not abundant).

9. 4. Light and radiation from the sun:
◦ Sunlight – energy for photosynthesis
◦ Source of energy for the water cycle and the
heating of the planet
◦ Little (UV) and ionising radiation
◦ Caused by
 Distance from the sun – light levels and temp
 Daily rotation – controls range of temps
 Tilted axis – seasonal variations
 Molten layers under the crust – creates a magnetic
field, deflects harmful radiation

10. 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.

11.  Transpiration
 is unavoidable (plants need gas
exchange/mineral transport), provide water
vapour to travel inland.
 produces water vapour, that travels inland .