Why is oxygen important
Oxygen (O₂) is necessary for the survival of all aerobic organisms, and that makes Oxygen probably the most important gas on planet. A large part of our nutrition and energy comes from oxygen itself and it is even more important than food or water. In order for cellular respiration to continue properly, the cells need a constant supply of oxygen, because it acts as an electron acceptor. As the cells are forced to practice anaerobic breathing in the absence of oxygen to complete the electron transport chain in the mitochondria, the cells heads towards certain death if oxygen is not restored quickly. Human beings and other aerobic creatures must combine oxygen with what they consume to release and use energy that is essential for their survival and functioning.
A common misconception is that plants do not need oxygen and they only release it. This is a faulty conception because even plants make their food with the help of oxygen and thus absorb a large quantity of oxygen during the night in order to combine with food to release vital energy. They need oxygen even in the daytime actually, but plants release the excess oxygen which is formed when they break up water and carbon dioxide to utilize the oxygen in them.
Apart from survival and energy needs of the biological creatures that depend on oxygen, there are also other important uses of oxygen. Oxygen is an all important gas necessary for combustion, without adequate oxygen, no fire can start and if the oxygen is limited in the area where the fire is burning, the fire will slowly burn out as the oxygen source depletes. Make no mistake though, oxygen is not a flammable gas unlike hydrogen or methane, it only acts as an accelerating agent for fire. It is due to this property of oxygen that it is used as an important part of the Bessemer process in steel plants. Oxyacetylene torches have incredible cutting and melting abilities due to the tremendous temperature that they produce and therefore have use in industrial operations. Oxygen is also an essential oxidizing agent put into the fuel tanks of a rocket.