3.1.1 Conditions For Life On Earth

Question 1

Main conditions allowing life to develop and survive

Answer 1

• atmosphere- carbon dioxide, methane, nitrogen. Atmospheric pressure and temperature maintained by liquid water.
• insulation - albedo, absorption of infrared energy
• position in solar system - distance from sun
• orbital behaviour - rotation and tilt on axis. Controls seasons.
• magnetosphere - deflects solar radiation.

Question 2

Biota maintaining stability

Answer 2

• oxygen production - photosynthetic bacteria, algae and plants.
• ozone layer
• carbon sequestration - CO2 concentrations reduced by photoautotrophs
• bio geochemical cycles

Question 3

Limitations and improvements of historical monitoring methods

Answer 3

Limitations:
- lack of ancient data
- limited reliable proxy data
- lack of sophisticate equipment
- reliance of proxy data e.g. dendrochronology, pollen analysis.

Improved methods:
- long term data sets
- electronic monitoring gas analysis of ice cores
- isotopes in ice cores
- monitoring equipment e.g. helium balloons, aircraft and satellites.