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28 Cards in this Set
- Front
- Back
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How old is the earth? |
4.6 billion years old 4600 million years old for w |
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For how long has the earths compositions being roughly the same |
200 million yearswhatb |
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What gases are present in our atmosphere today |
Nitrogen Oxygen Argon Carbon Dioxide Water Vapour |
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Percentage of nitrogen |
78% |
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Percentage of oxygen |
21% |
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Percentage of other gases (carbon dioxide, argon and water) |
1% |
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What gases were present in the earths atmosphere originally |
Mainly carbon dioxide Water Vapour Methane Ammonia |
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What did the early earths atmosphere resemble? |
Venus and Mars atmosphere now |
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Theory about Earth |
Intense volcanic activity and it was very hot when formed Volcanoes released : carbon dioxide, methane, ammonia and water vapour |
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Where did oxygen come from? |
PlAnts evolves and used carbon dioxide for photosynthesis when reacting with water which produced oxygen |
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Photosynthesis word equation |
Carbon dioxide + water —> glucose + oxygen |
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Photosynthesis balanced equation |
6 CO2 + 6 H20 —> C6H12O6 + 6 O2 |
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Earliest form of life on earth |
Cyanobacteria |
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Cyanobacteria |
Type of algae 2.7 billion years old according to fossil evidence |
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What happened to the water vapour |
Condensed to form the oceans |
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What happened to the methane |
Locked up in the earths crust, useful as a fossil fuel And reacted with oxygen to for form carbon dioxide and water |
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Formation of nitrogen |
Nitrogen fixing bacteria in the soil that turns nitrates into nitrogen gas Ammonia reacted with oxygen to form nitrogen and water |
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Why is there so much nitrogen now? |
Nitrogen is inert so it stays in the atmosphere |
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What did the oxygen in the atmosphere develop? |
An ozone layer, which filters out harmful ultraviolet radiation from the sun allowing evolution of new living organisms |
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What happened to the ammonia other than making nitrogen |
Made amino acids |
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Two main ways CO2 decreased |
Dissolved in oceans Used in photosynthesis |
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CO2 dissolves in oceans and forms what two things at first |
Forms insoluble compounds and soluble compounds |
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Insoluble compounds |
Becomes sediment which forms sedimentary rock such as limestone which contains calcium carbonate |
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Soluble Compunds |
Animals take these compounds in, animals decay leaving shells and skeletons which become sediment and form sedimentary rock |
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CO2 can be used in photosynthesis by what two things |
Planktons in the ocean (including algae) Plants in swamps |
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Plankton in the ocean |
Decay under heat and pressure to form crude oil and natural gas |
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Plants in swamps |
Decay under heat and pressure and forms a sedimentary rock: coal
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Why were gases from inside the earth released? |
The pressure inside the earth was larger than above the surface |
