Oxygen:
Oxygen is the gas that everyone's body needs to function the way it's supposed to. All of our cells need oxygen to create the energy we need. Our lungs also need oxygen and absorbs the oxygen we breath. The oxygen we breath travels to our organs and body tissues, helping us survive.
Nitrogen:
Nitrogen is a very important nutrient for amino acids, proteins, and nucleic acids. Nitrogen is absorbed by roots as ammonium or nitrate, which also help life be possible.
Carbon Dioxide:
Carbon dioxide is a very important gas that helps trap heat in our planet. Without carbon dioxide, Earth would be extremely cold. Although carbon dioxide helps protect our planet from the extreme cold, the CO2 concentrations in our atmosphere have caused the temperatures to rise all over the world, which has caused there to be lots of natural disasters.
Hope this helps =)