why do think oxygen is used to breath instead of using carbon dioxide.

Question

snuggielad · Answer

Oxygen is used to breath becuase it is capable of making energy your body needs to run itself. 
the oxygen is breathed in and gets released from the lungs and oxygen molicules get picked up by the blood stream.  Then the oxygen molicules go to each cell and the cell changes it into water which it will use to run everyday functions that the cell has to do in order to survive. 
as you can see the nessesity of oxygen goes down to the cellular level.
Carbon Dioxide can not do all the functions oxygen can. Trees take in carbon dioxide becuase they are not in need of water from gasses. they are fed by a root system. this root system provides water and if you take the water away the tree will die...you notice that it didnt get it from the carbon dioxyde because carbon dioxide cant make water.

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aaronq · Answer

Your answer is correct overall, except where you say we need to breathe to acquire water, which isn't true. Yes, water is produced from the reduction of oxygen, but oxygen is involved in the oxidation of glucose (specifically at the electron transport chain) to synthesize adenosine triphosphate (ATP) - "cellular currency". Oxygen is used because of it's high electronegativity (opposed to CO2).

agreene · Answer

You're also incorrect to say we breath to obtain oxygen, we breath to release COx species, Ox exchange is more of a happy accident.

aaronq · Answer

You make a good point about CO2. But, although were capable to produce ATP anaerobically, it's not nearly as sufficient to generate enough (being multicellular organisms and all) and thus we DO breathe to obtain oxygen as it cannot simply diffuse into our cells.

agreene · Answer

The amounts of Ox species we get are amazingly low from inhalation, think about how many moles of Oxygen are in everything you eat and drink--thats where we draw the vast majority of our Ox species

aaronq · Answer

hm but if oxygen is sequestered within a molecule it won't function the same. I really don't think that's true by the mere fact that we won't survive if we don't breathe even for a few minutes.