why is it tat only oxygen and not any other gas important for survival of life?
101749
When oxygen combines with combustible material, such as carbon, a great deal of energy is released.  You and I get our energy from these reactions (and life depends on energy).  However, not all life on earth uses oxygen for energy.  Anaerobic bacteria, for instance; the name means "no air", and oxygen kills them.\n\nAlmost all the oxygen in our atmosphere was originally released by living things, and it was poisonous to the first life!  One of the most remarkable things about using oxygen is that Life adapted to what was originally a deadly poison, until it became a necessity.
958887
Lavender gave you the key information you need, i.e., too much oxygen damages the body. Probably the best-known example of this is blindness in prematurely born infants due to breathing pure oxygen for extended periods (which is sometimes necessary to keep them alive). There are probably medical techniques available today to minimize this problem, but it has been a serious issue in past years (20 years ago in one example I am familiar with).\n\nHere is a bit more information about breathing pure oxygen, and some clarification of the comments from others.\n\nYou can breathe pure oxygen for short periods in order to recover from lack of oxygen (athletes do it, as do firemen who have inhaled smoke, for example).\n\nThe air we breathe at sea level is at a pressure of 14.7 psi, and 21% of it is oxygen. (78% is nitrogen, and most of the other 1% is argon.) If you take 21% of 14.7psi, you'll see that we are breathing oxygen at a pressure of about 3 psi.\n\nPilots and astronauts can breathe pure oxygen, but as Lavender points out, they breathe oxygen at a pressure lower than sea level air pressure. If their oxygen is delivered to them at 3 psi, then it is equivalent to the oxygen in our air at sea level. (And incidentally, the air we breathe is not much changed at elevations up to 5,000 or 10,000 feet. As a rule of thumb, you can notice the difference in air pressure (the difference in the availability of oxygen) when you get close to 10,000 feet of elevation. At 18,000 feet, the air pressure is about 50% of that at sea level. And after another 18,000 feet, the pressure at 36,000 feet is cut in half again, so it is about 25% of the sea level pressure.)
931037
Water, you can not sustain life without it. That includes every form of life, man, animal, forests, bacteria, etc. Everything!\n\nAir, which contains oxygen on which we as human beings depend on for our dear life.\n\nSunlight, which is the beginning of our very existence. Imagine what life would be if there was no sun. \n\nThere are many other natural resources which surround us on this wonderful planet called the Earth. But I would say that these three definitely top the list.\n\nBy the way, you ask very intelligent questions. Good for you to be so concerned about your enviornment.
292621
It is due to natural selection. Those of us who can breath oxygen without suffocating survive and those who can't die.
918461
So far, science knows that in every life there is oxygen and protein or amino acid but other constituents are not known yet. Hindus believe that there is a life energy which is a property of Nature that is more vital than the material property as detected by the modern Science.
606970
Ok, what gas is required for combustion??  OXYGEN!\nHydrogen and oxygen combine and release large amounts of energy/heat while form water in small amounts (in the form of vapor).  \n\nAs for other gases, carbon is the element "burning", but there must be oxygen present in the moluecule or in the environment to burn.\n\nThis is different for hydrogen in stars, which are undergoing fusion.
373695
oxygen is needed to convert glucose into energy.Without oxygen the body cant make energy without making lactic acid as well. Thats why you get stitches when you run out of breath. Didnt you pay attention in biology?
791055
it is impossible to answer the first question since at the big bang there was at lest the first  thousand years no atoms.\n\nMany animals  need oxygen  for their need in energy. But for some bacteria oxygen is a poison\n\nOxygen is important to animals since the nervous cells  die quickly without oxygen
683788
If you mean breathing nitrogen, nothing as long as there is some oxygen mixed, if you dive deeply nitrogen can dissolve in your blood and make little bubbles when return to the surface and it can be mortal\n\nIf you mean nitrogen in nutrition, it's very important in forming proteins, if it lacks can cases lack of proteins, and if you receive too much it can leads to suffering from exceeding of uric acid.
473126
Hydrogen. You can create it from water using only electricity so it's the cheapest fuel ever. When you explode it (during combustion), it mixes with oxygen to create...you guessed it...water (no polution).\n\nSo:\n1.Free\n2.No polutants\n\nHmmm...
131253
Cause cells need oxygen.
1057801
The air is the gaseous compounds and elements that make up the Earth's atmosphere.\n\nThe essence of the air is that it is made up of mostly Nitrogen (78%), and also a fair amount of Oxygen (21%), plus Argon and a myriad of other gases including water vapour, ozone and carbon dioxide.\n\nOxygen is probably the most important element for humans, as our metabolism has evolved to utilize oxygen as the ultimate electron receptor in the biochemical pathway that provides the energy to run the metabolic processes that keep our body, and most importantly our energy hungry brain, operating.\n\nWithout oxygen, our body is forced to switch to the 'back-up generator' of anaerobic respiration, and that pathway simply doesn't provide enough energy to keep our body operating for very long.  It works fine for some bacteria, but we need a bit more oomph in our catabolism.\n\nThe atmosphere also shields us from some of the harmful effects of the radiation of our sun, such as ultraviolet radiation, and makes temperature and climate more stable, holding heat when the sun isn't shining on us, and taking longer to heat up when it is shining.  Thus it also makes our lives more comfortable.\n\nPlus if we didn't have the air, it wouldn't be there to refract light and make the sky blue, or form regions with big fluffy poofs of water vapour to scud lazily across the blue sky on a lazy summer afternoon, or provide a medium in which butterflies can dance prettily in summer air.\n\nSo I have no idea what 'quimic composition' is, but that's the essence of air.
688444
In addition to the oxygen, water, issues previously discussed, the surface is under constant attack by radiation and high energy particles due to the lack of a sufficient atmosphere.  We would have some mutated DNA after too long on the surface.  That's not too good.
455306
Oxygen, like a lot of substances our body needs, can be harmful in large quantities.  This is partly due to its highly electromagnetic and hydrophyllic nature.  As any patient that has been on oxygen therapy can tell you, your body is "set" to use a certain percentage of oxygen in the air we breathe.  If we get used to a higher amount, and then this amount is depreived, we feel light-headed and weak.  This is because at higher levels of oxygen, our lungs become accustomed to a smaller amount of effort to extract and use the oxygen from the air.  \n\nOxygen's corrosive nature is not found in the O2 form however, but the O and O3 (ozone) forms.  This is because oxygen is most stable in the O2 form.  This is where oxygen "wants" to be.  The O3 and O forms are unstable, and prone to reactions.    \n\n"Oxygen can be toxic at elevated partial pressures (i.e. high relative concentrations). This is important in some forms of scuba diving, such as with a rebreather.\n\nCertain derivatives of oxygen, such as ozone (O3), singlet oxygen, hydrogen peroxide, hydroxyl radicals and superoxide, are also highly toxic. The body has developed mechanisms to protect against these toxic compounds. For instance, the naturally-occurring glutathione can act as an antioxidant, as can bilirubin which is normally a breakdown product of hemoglobin. To protect against the destructive nature of peroxides, nearly every organism on earth has developed some form of the enzyme catalase, which very quickly disproportionates peroxide into water and dioxygen.\n\nHighly concentrated sources of oxygen promote rapid combustion and therefore are fire and explosion hazards in the presence of fuels. The fire that killed the Apollo 1 crew on a test launchpad spread so rapidly because the capsule was pressurized with pure oxygen as would be usual in an actual flight, but to maintain positive pressure in the capsule, this was at slightly more than atmospheric pressure instead of the 1/3 pressure that would be used in flight. (See partial pressure.) Similar hazards also apply to compounds of oxygen with a high oxidative potential, such as chlorates, perchlorates, and dichromates; they also can often cause chemical burns.\n\nOxygen derivatives are prone to form free radicals, especially in metabolic processes. Because they can cause severe damage to cells and their DNA, they form part of theories of carcinogenesis and aging." (Wikipedia 2006)\n\n"Oxygen is the most abundant element on this planet. The earth's crust is 46.6% oxygen by weight, the oceans are 86% oxygen by weight, and the atmosphere is 21% oxygen by volume. The name oxygen comes from the Greek stems oxys, "acid," and gennan, "to form or generate." Thus, oxygen literally means "acid former." This name was introduced by Lavoisier, who noticed that compounds rich in oxygen, such as SO2 and P4O10, dissolve in water to give acids.\n\n"Fluorine is the only element that is more electronegative than oxygen. As a result, oxygen gains electrons in virtually all its chemical reactions. Each O2 molecule must gain four electrons to satisfy the octets of the two oxygen atoms." ("Chemistry of Oxygen" - Bodner Research Group)
83781
No oxygen in space. Need to bring or make your own.\nNo gravity or very weak affects the human body in many ways, one big is it weakens ones bones(and muscles).
225820
Yes, it is the increased level of CO2 that signals the gas concentration in the blood, because during evolution, if you were low in oxygen you were almost certainly high in CO2.  BUT, in high altitude, you can have low oxygen without having high CO2, because you are blowing out your CO2, as normal, but not taking in greater oxygen-this leads to a dangerous situation in that you are not stimulated to breath more, and are not signalled that you are not getting enough oxygen.  At high altitude, especially dangerously high, you dont always feel horribly out of breath-in fact, the low oxygen levels cause poor judgement and reduced cognition, the absolute worst thing to happen in that kind of situation.
862118
Because they can happen with oxygen present.  These processes require another electron acceptor to replace oxygen as in aerobic respiration.  The word anaerobic literally means without the presence of oxygen