How the presence of life on Earth brought about environmental change
Description
AS Level Environmental Studies (Early life on Earth brought about environmental change) Mind Map on How the presence of life on Earth brought about environmental change, created by elliehaf11 on 09/05/2013.
How the presence of
life on Earth brought
about environmental
change
ATMOSPHERIC
OXYGEN
Oxygen is a reactive
element, concentration
declined when it reacted
with other elements eg)
oxidation weathering
Continued presence of
oxygen in atmosphere relies
on processes that replace it
as other processes remove it
Small amount of
oxygen released by
photolysis of water and
photosynthetic bacteria
Oxygen absorbed UV
light from sun, oxygen
molecules then split,
produced monatomic
oxygen which reacts with
diatomic oxygen to
produce O3/Ozone
Allowed ozone layer to form,
provided protection from UV
light to living organisms.
Before this
abundant life
not possible
so early
organisms
lived in
oceans
where water
protected
them from
UV light
ATMOSPHERIC
CARBON DIOXIDE
Naturally
released into
atmosphere
by volcanoes
Essential greenhouse gas,
helps maintain heat in
atmosphere, without it Earth
would be too cold to sustain life
Excessive CO2
levels would cause
temperatures to
rise too high for
life to survive
Light output of the sun
increases by 10% every
billion years so 30% brighter
than when life first developed
Living organisms helped maintain
suitable atmospheric temperatures by
removing CO2 (photosynthesis) and
storing in fossil fuels and carbonate
rocks (chalk/limestone)
THE
HYDROLOGICAL
CYCLE
Heat energy from absorbed
sunlight causes water in the
sea to evaporate
May be carried over
land where it falls as rain
then flows back to sea
Most rain falls relatively close
to the coast but transpiration
by plants returns water
vapour to the atmosphere so
it can be blown further inland
Transpiration from leaves is
unavoidable as the stomata must
open for gas exchange