c9 - evolution of the atmosphere Flashcards
what are the main gases and their %?
nitrogen - 80%
oxygen - 20%
other gases eg ( carbon dioxide and water vapour ) - <1%
what was the earth like in the first billion years?
very dry
intense volcanic activity
what did the volcanic activity produce?
carbon dioxide
water vapour
nitrogen
what happened to the water vapour as years went on?
condensed and formed oceans
what did the condensed water vapour allow and create?
lots of carbon dioxide from the atmosphere to dissolve in them, making:
- carbon precipitates
- sediments in the seabeds
what slowly happened 2.7 billion years ago to the atmosphere and why?
slowly algae began to appear, but became more rapid as green plants evolved because these groups of organisms are able to photosynthesize
whats the formula for photosynthesis?
carbon dioxide + water = glucose + oxygen
what happened over time to the amount of carbon dioxide and why?
the amount slowly declined because as more plants were made, the more carbon dioxide was taken in for photosynthesis
what happened to the amount of oxygen over time and why?
slowly built up because more plants were photosynthesising and releasing more oxygen
what does carbon dioxide and oxygen allow?
allows more complex life like animals to evolve
what happens when algae and green plants die? [ 3 ]
- they can only a small amount of carbon in their bodies
- fall to the seabed and become buried in layers of sediment
- over millions of years, the sediment became compressed to form: - sedimentary rock
- oil and gas
what is crude oil and natural gas formed mainly from?
dead plankton
what is coal and what is it made from?
- a type of sedimentary rock
-made from thick deposits of dead plant material
what is limestone and what is it made from?
- sedimentary rock
- made from calcium carbonate that marine organisms incorporate into their shells and skeletons
