why is oxygen so important to keep things alive?
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HISTORY OF OXYGEN\n\nIt's difficult to think of free oxygen, which makes up 21 percent of earth's atmosphere, as a poisonous gas. Virtually all organisms alive today need oxygen to survive. Even plants, which expel oxygen into the atmosphere, need oxygen to live. There was a time early in earth's history, however, when living organisms not only did not need oxygen, but were killed when exposed to the element. \n\nThree and a half billion years ago, Earth's atmosphere contained almost no free oxygen. Instead, it consisted mainly of carbon dioxide, perhaps as much as 100 times more carbon dioxide than contained in today's atmosphere. During this time, Earth's only life forms were aquatic, one-celled organisms -- primitive forms of bacteria -- that extracted energy from a variety of sources. To most of these organisms, free oxygen was poisonous. \n\nAt about the same time, new types of primitive bacteria evolved. Unlike their predecessors, these bacteria could convert energy directly from the Sun, through photosynthesis. One type, bluish-green organisms called cyanobacteria, used sunlight to convert carbon dioxide and water into glucose (sugar). These organisms expelled oxygen gas -- a by-product of photosynthesis -- into the oceans. \n\nAs the cyanobacteria multiplied and spread around the globe, they released more and more free oxygen into the oceans. This oxygen combined with the molecules of living bacteria, killing them off as it did so. It also combined with other matter, such as the iron dissolved in the ocean. Only after the oxygen combined with all of the matter available did free oxygen begin to accumulate in the oceans. And when the oceans became saturated with oxygen, it began to make its way into the atmosphere. \n\nOrganisms that don't need free oxygen to survive are called anaerobic; all living things that need free oxygen, including us, are aerobic organisms. As the oceans and atmosphere filled with oxygen gas, aerobic life evolved further, at some point adding a nucleus to the cell (to protect the cell's DNA from the harmful effects of oxygen) and eventually to multi-cellular organisms. Anaerobic life, on the other hand, was pushed back to areas where there was little or no oxygen. Today, anaerobic organisms like those that existed more than three and a half billion years ago live in oxygen-free places such as volcanic hot vents, where they get their energy in ways other than from carbon dioxide, water, and sunlight.\n\nIMPORTANCE OF OXYGEN\n\nCirculatory System, or cardiovascular system, in humans, the combined function of the heart, blood, and blood vessels to transport oxygen and nutrients to organs and tissues throughout the body and carry away waste products. Among its vital functions, the circulatory system increases the flow of blood to meet increased energy demands during exercise and regulates body temperature. In addition, when foreign substances or organisms invade the body, the circulatory system swiftly conveys disease-fighting elements of the immune system, such as white blood cells and antibodies, to regions under attack. Also, in the case of injury or bleeding, the circulatory system sends clotting cells and proteins to the affected site, which quickly stop bleeding and promote healing.\n\nRespiratory System, in anatomy and physiology, organs that deliver oxygen to the circulatory system for transport to all body cells. Oxygen is essential for cells, which use this vital substance to liberate the energy needed for cellular activities. In addition to supplying oxygen, the respiratory system aids in removing of carbon dioxide, preventing the lethal buildup of this waste product in body tissues. Day-in and day-out, without the prompt of conscious thought, the respiratory system carries out its life-sustaining activities. If the respiratory system’s tasks are interrupted for more than a few minutes, serious, irreversible damage to tissues occurs, followed by the failu
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The amount of O2 produced depends on the rate of photosynthesis, \nnot the breadth of the leaves.  Fast growing plants under good \nconditions produce the most O2.
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Plants play a vital role in our living.\nThey are the very source of Oxygen that make life possible.\n"Plant a Tree to Save a Life."\nIf you protect a tree, it will protect you.
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water food oxygen environment
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It doesn't need to, it just absorbs oxygen from the water directly through its cell membranes.
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to carry nutrients, oxygen, wastes to/away from body cells.
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depends upon the environment.  Under normal conditions, a few hundred pounds will suffice to keep the diaphram from inflating the lungs.  In deep water, there are experimental blends that allow oxygen levels to be maintained.
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Oxygen is the only gas we really need to breathe in order to stay alive. If we don't breathe oxygen (or if we don't breathe enough oxygen), we soon die. Interestingly enough, too much oxygen can be a bad thing also. At right is a diagram illustrating the range of oxygen concentrations that we can breathe safely. The green and red bar represents a scale of inspired oxygen partial pressures (PO2), ranging from zero oxygen on the left, to a PO2 of 2.0 ATA on the right. Through evolution, our bodies have become optimized to breathe oxygen at a partial pressure (PO2) of 0.21 ATA. If the inspired PO2 is much less than this, our bodies begin to shut down -- leading to unconsciousness when the PO2 drops below about 0.1 ATA (i.e., 10% oxygen at sea level). This is called hypoxia. Breathing more than 0.21 ATA oxygen is generally fine ... up to a point. If the inspired PO2 is maintained above about 0.5 ATA for prolonged periods of time (many hours to days), people begin to suffer what is usually referred to as "pulmonary" or "chronic" oxygen toxicity. The effects of this include a burning sensation or irritation in the lungs, and can affect breathing. Except for people who spend days under pressure at a time (e.g., commercial divers on oil rigs), this form of oxygen toxicity is not much of a problem for divers.\n\nHowever, as the inspired PO2 starts to climb above about 1.2 to 1.4 ATA, another kind of oxygen toxicity, called "CNS" (for "Central Nervous System") or "acute" oxygen toxicity, becomes a significant problem. Although a variety of subtle symptoms such as muscular twitching in the face and tunnel vision have been attributed to this kind of oxygen toxicity, the really important symptom is severe, uncontrolled convulsions. Although these convulsions do not appear to cause any sort of permanent damage by themselves, the problem of a diver experiencing such convulsions being able continue to hold a regulator in his or her mouth is obvious. More than a few divers have drowned underwater, apparently a result of oxygen-induced convulsions. This is perhaps the most serious and insidious of diving maladies, because it comes on unpredictably and without warning, and usually results in the death of the afflicted diver.\n\nThere is no clear understanding on the exact biochemical processes involved with CNS oxygen toxicity, nor is there a clear consensus on what the "safe" upper PO2 limit should be. Convulsions have occurred in divers breathing an inspired PO2 as low as 1.2 ATA, but such cases usually involve extenuating circumstances (such as medical conditions in the divers which pre-dispose them to convulsions). Conversely, commercial divers in Europe have routinely breathed oxygen partial pressures as high as 1.9 ATA in the water, and hyperbaric chamber facilities regularly expose patients to 2.8 ATA of oxygen (or more) without difficulty. Amid the ambiguities, two trends seem very consistent. The first is that high levels of exercise (perhaps more specifically, high levels of CO2 in the blood) appear to increase the probability of suffering from a convulsion. Secondly, divers immersed in water have a lower tolerance to elevated concentrations of inspired oxygen than do divers kept dry in a hyperbaric chamber or undersea habitat. (this over and above the fact that divers in a dry habitat are much more likely to survive a convulsion than are divers immersed in water). Another unavoidable reality regarding oxygen toxicity is the extreme range of variation both between individuals, and within a single individual.\n\nWhen immersed underwater, most divers regard a PO2 of 1.4 ATA as a safe upper limit during periods of physical exertion, and 1.6 ATA during periods of rest.
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The more co2 the more o2 that will be produce the more oxygen rich the environment the better the growth of living things.
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The only aswer to this is- grow more and more trees. Trees produce oxygen, it helps to increase rainfall, it helps to maintain temperture. so grow more and more trees and save earth.
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Trees are a major contribution to the oxygen we breathe. There are many plants used in the production of the medicines that cure our ills and keep us alive.
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WindWalker's statement that oxygen is necessary for the synthesis of nutrients we need is a little misleading.  Oxygen is basically the end of the electron transport chain, and binds hydrogens that have passed though the ion gradient of the mitochondiral matrix to form water.\n\nHydrogen passes through this gradient in the mitochondrial matrix via passive, channel mediated transport.  The concentration of H+ on one side is high, and low on the other, since they get bound to Oxygen to form water.  Every time an H+ ion passes through, energy for ATP production is derived.
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life needs not only oxygen but othere conditions as well. Life needs essentailly he fore of gravity for the proceses of life to be active .It is graiy tha keeps the sir balanket over the surfaxce oif he earth . But for that , the air would vanish into thin air ! - would anish into space . Water would not flow and our food would not go doen  our throat and would not even be able to defecate . aain the climate is also imporant . We hae go to be at a distncefrom the dun hat would be expose us to a ligh and heat that is cinsucive to the development of live and tolerable to life .ALL  he planets around the sun are not locaed at a sistance very conducive to the deelopmemt of life like us .and all of hem dfo not hav a gaviy  tha is suitable for the fuctioning of our system . We are not independent of our great mother earth. We will not survive in any planet which dose not hae an amospher  and gavity like the earth. Oxygen alone won't  help us live .Since the building blocks of all elemens ar the same - electron and proton - we would be able create oxyen in any planet by a suiable process that man would be able to create by manipulaing the numbver of electrons in the aoms of any subasance aailable in any pkanet . We do not hae to transfer oxygen anywhere . we can create oxygen from   whatever is available anywhere.
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Warm water holds less oxygen than cool water, so it may be saturated with oxygen but still not contain enough for survival of aquatic life.
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Because some of the planets have evidence of water and also might have a warm enough climate to support life on that planet, some of them have oxygen as well.
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oxygen...almost everywhere, anyway.
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80g of oxygen was produced because that is the difference between the beginning mass and the ending mass. mass is conserved during the reaction, it needs to balance.