Another form of oxygen, O3, also known as ozone is very important in protecting us life forms from high-energy radiation. O3 travels up to very high altitudes and absorbs the high-energy radiation before it gets to us. Without it, we’d have a lot of skin cancer going around, and most likely no plants to eat. Pretty much, we’d all die.

Oxygen also plays an important role in combustion reactions (when things burn and fire is involved). The burning material contains carbon and hydrogen (sometimes oxygen also) and when it burns, it creates CO2 and H2O.

If there is not enough O2 available when a combustion reaction is occurring, then the products are CO and H2O. Co is pretty toxic, which is why it has the nickname “the silent killer.” It’s odorless, colorless, and it bonds REALLY strongly to our hemoglobin, so it pretty much suffocates us without us realizing it. So, it’s important that there is enough O2 present when burning something.

CO2 is a pollutant because the quantity of it right now it pretty high, but if we didn’t have ANY CO2, then plant life would die out. Pretty much, plants “breathe in” CO2, and “breath out” O2. Since CO2 is mostly O2, then I’d say that’s another important role that oxygen has.

The development of an oxygen-rich atmosphere was one of the most important events in the history of life on earth. The presence of large amounts of dissolved and free oxygen in the oceans and atmosphere may have driven most of the anaerobic organisms then living to extinction during the oxygen catastrophe about 2.4 billion years ago. However, the high electronegativity of O2 creates a large potential energy drop for cellular respiration, thus enabling organisms using aerobic respiration to produce much more ATP than anaerobic organisms. This makes them so efficient that they have come to dominate earth’s biosphere.[7] Photosynthesis and cellular respiration of oxygen allowed for the evolution of eukaryotic cells and ultimately complex multicellular organisms such as plants and animals.

Even flame will be put out with out oxygen.