atmospheric gases

• Atmosphere is composed mainly of nitrogen, oxygen, carbon dioxide, water vapor, and trace amounts of other gases.
• The atmosphere is the layer of air that surrounds Earth.
• oxygen which has 21 percent, nitrogen which is 78 percent, and carbon dioxide which has 0.03 percent
• carbon dioxide is used by plants during photosynthesis
• plants and animals need nitrogen to manufacture protein
• plants cannot use nitrogen gas directly from the air, it has to be converted to nitrates before plants absorb it
• animals get their nitrogen from the plants they eat