C6.3 Flashcards
1
Q
What has the atmosphere evolved
A
The atmosphere is mostly made of helium. Volcanoes release carbon dioxide and water vapour. water vapour condensed to form oceans. Photosynthesis by plants and algae produces oxygen. Oxygen forms the ozone layer. Layers of nitrogen in the atmosphere increase. Carbon dioxide stored in fossil furs is released
2
Q
How has the level of oxygen in the atmosphere changed over time
A
When plants and algae first evolved, photosynthesis reduced the amount of carbon dioxide in the air and released oxygen. The oxygen produced reacted with metals to form oxides that we find in rocks
