C9

Question 1

what are the three phases?

Answer 1

Phase 1=Volcanoes gave out gases
Phase 2=Oceans,algae and green plants absorbed carbon dioxide
Phase 3 =Green plants and algae produced oxygen

Question 2

how was the early atmosphere formed (phase 1 volcanoes)?

what was the early atmosphere like?(2)

what did volcano activity release and what did it do?

Answer 2

-They were formed by the surface was covered in volcanoes that erupted and released lots of gases
-They were mostly carbon dioxide,with virtually no oxygen.
-They released nitrogen which built up in the atmosphere overtime as well as water vapour and small amounts of methane and ammonia

Question 3

what happens when water vapour in the atmosphere condenses?
why was alot of carbon dioxide remove from the early atmoshpere and what did it go through?
why did green plants and algae evolve and absorbed some of carbon dioxide?
what later evolved?

Answer 3

-When it condenses it forms oceans
-It was removed as it dissolved in oceans.It went through a series of reactions to form carbon precipitates that formed sediments on the seabed
-They both evolved so that they could carry out photosynthesis
-Later marine animals evolved their shells and skeletons contained carbonates from the oceans

Question 4

what happens when plants plankton and marine animals die?(3)
what are fossil fuels?
how are crude oil and natural gas formed?
what is coal?
what is limestone?
what is crude oil and natural gas formed from

Answer 4

-They fall to seabed and get buried by layers of sediment,Over millions of years they become compressed and form sedimentary rocks,oil and gas trapping the carbon with them and helping to keep carbon dioxide levels in the atmosphere reduced
-Fossil fuels are things like coal,crude oil and natural gas
-Coal is a sedimentary rock made from thick plant deposits
-Limestone is also a sedimentary rock mostly made from calcium carbonate
-Crude oil and natural gas are formed from deposits of plankton

Question 5

In phase 3 green plants and algae produce?(2)
what evolved first algae or green plants?
As oxygen levels increase in the atmosphere what happened overtime?
what are the proportions of different gasses in the atmosphere for 200 million years?(3)

Answer 5

-Produced oxygen from photosynthesis.This is when plants use light to convert carbon dioxide and water into sugars
-Algae evolved first about 2.7 billion years ago,then green plants evolved over the next billion of years
-As oxygen levels increase in the atmosphere overtime more complex life (animals) could evolve

Proportions of gasses:
-approx 80% nitrogen
-20% of oxygen
-small amounts of other gases mainly like carbon dioxide,noble gases and water vapour