Oxygen in the atmosphere
- Created by: shauna gardner
- Created on: 04-09-12 17:12
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Levels of oxygen in the atmosphere have changed. over 2 billion year oxygen levels have steadily risen. it is now 21% of are atmosphere. scientists believe it is because of evolution of such plants like algae. they say the carbon dioxide was used up by the photosynthesis of them.
Photosynthesis produce the first molecules…
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