Atmospheric gases

• most important gases

  oxygen, which is 21 percent, carbon dioxide 0,03 percent and Nitrogen which makes up 78 percent of air.
• plants cannot use nitrogen gas directly from the air, it has to be converted into nitrates before plants absorb it
• animals get their nitrogen from the plants that they eat
• stomata is a small opening in plant which permit gas exchange
• carbon dioxide and oxygen in water is less than in the atmosphere so plants under water have to find a way to get enough oxygen
• the absence of cuticles helps plants to absorb gases from the surrounding plants on the surface
• transpiration is the process by which water evaporates through stomata