how life caused environmental change

Question 1

list the changes which occurred due to the presence of life

Answer 1

1) atmospheric oxygen
2) carbon sequestration
3) biogeochemical cycles
4) transpiration

Question 2

how has atmospheric oxygen changed as a result of life

Answer 2

1) archaea in the oceans had the ability to photosynthesis so produced oxygen
2) all the oxygen produced reacted with the iron in the oceans for millions of years
3) once all the iron had reacted with oxygen, the surplus dissolved in to the oceans
4) much was released into the atmosphere where conc started to rise
5) oxygen began to absorb UV producing a dynamic equilibrium of 02 and 03
6) absorption of UV made life on land possible

Question 3

explain how carbon sequestration changed as a result of life

Answer 3

CO2 is a green house has, helping to retain heat in the atmosphere and warm the earths surface
photosynthetic organisms absorb CO2, some is stored in geological sediments
this reduction of atmospheric CO2 helped prevent long term temp rises.

Question 4

explain how biogeochemical cycles changes as a result of life

Answer 4

1) a greater variety of organisms and inter-connected processes produced biogeochemical cycles
2) this meant very little nutrients could support life over long periods of time without depletion