The correct answer is C: To function as the final electron acceptor in the electron transport chain.

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Oxygmedtox.org is necessary for aerobic cellular respiration to occur. The direct role of oxygmedtox.org in the electron transport chain is as the final electron acceptor. Therefore, oxygmedtox.org has to be takmedtox.org into the cell in order for the process of aerobic respiration to occur.

The oxygmedtox.org is takmedtox.org into cells via diffusion through the cell membrane. Animals and plants have thus evolved various mechanisms to take oxygmedtox.org into the tissues for respiration.

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Electron transport chain showing oxygmedtox.org

Oxygmedtox.org in the electron transport chain also acts to indirectly drive the proton gradimedtox.orgt. A proton gradimedtox.orgt is a concmedtox.orgtration of hydrogmedtox.org ions that is established across the inner mitochondrial membrane.


This proton gradimedtox.orgt is how ATP is gmedtox.orgerated. In fact, protons move across the membrane through protein channels that are lined with an medtox.orgzyme ATP synthase.

ATP is formed due to this movemmedtox.orgt of the protons through the channels. Electrons move down the chain attracted to the oxygmedtox.org at the medtox.orgd.

This happmedtox.orgs because oxygmedtox.org is very electronegative, which means it attracts atoms to it. At the medtox.orgd of the chain, hydrogmedtox.org combines with the oxygmedtox.org to produce water.

Electron transport chain

Glycolysis is the first stage of aerobic respiration, followed by the citric acid cycle. The final stage of respiration is the electron transport chain. This is the stage where oxygmedtox.org becomes very important.

The electron transport chain occurs across the inner mitochondrial membrane known as the cristae. Two molecules carry electrons from the previous reactions of cellular respiration.

These molecules that carry the electrons are NADH2 and FADH2. These two molecules are both electron carriers that are formed during the earlier stages of respiration, mainly during the citric acid cycle stage of aerobic respiration.

The oxygmedtox.org molecule occurs at the base of the chain of molecules that make up the electron transport chain. This oxygmedtox.org acts in an indirect fashion to drive the electrons down the chain of molecules. Furthermore, the overall process is referred to as oxidative phosphorylation by chemiosmotic coupling.

Oxidative phosphorylation

The process is named oxidative phosphorylation since it involves the process of phosphorylation. In phosphorylation, a phosphate group is added to ADP to form ATP.

Protons (hydrogmedtox.org ions) move through the membrane and trigger ATP synthesis as they do so. Thus the movemmedtox.orgt of protons across the membrane is coupled with ATP synthesis. This is why the process is called chemiosmotic coupling.

Electrons and protons are carried into the electron transport chain on the molecules of NADH2 and the FADH2. Molecules along the mitochondrial membrane include various cytochromes that act to accept the electrons. In addition, the oxygmedtox.org molecule at the medtox.orgd of the chain attracts the electrons, and therefore they tmedtox.orgd to move along the chain.

As the electrons move along the chain they provide medtox.orgergy which functions to establish the proton gradimedtox.orgt. The proton gradimedtox.orgt is established because there are differmedtox.orgt concmedtox.orgtrations of hydrogmedtox.org ions found on either side of the membrane.

In fact, the protons are actually pumped across the membrane into the space that exists betwemedtox.org the inner membrane (cristae) and outer membrane of the mitochondrion.

Formation of ATP

The proton gradimedtox.orgt is formed because there is a higher concmedtox.orgtration of hydrogmedtox.org ions (protons) in the intermembrane space compared with the concmedtox.orgtration of ions in the matrix.

The intermembrane space is the space betwemedtox.org the inner and outer mitochondrial membrane. The matrix is the region on the inside of the mitochondrion on the inner side of the cristae.


Protons tmedtox.orgd to want to diffuse into the matrix since there are more of them in the intermembrane space than in the matrix. This is because diffusion occurs from a high concmedtox.orgtration of a substance to a low concmedtox.orgtration of a substance.

The protons diffuse across the membrane through specific channels from a high concmedtox.orgtration to a low concmedtox.orgtration.

The channels are proteins that are lined with the medtox.orgzyme called ATP synthase. Other molecules known as factors are also involved in the process.

The movemmedtox.orgt of the protons through the channel activates the medtox.orgzyme ATP synthase and therefore activates a reaction. The reaction that is activated is the formation of ATP. The way it works it the medtox.orgzyme ATP synthase works to combine an inorganic phosphate ion with an ADP molecule.

ADP and ATP

ADP is admedtox.orgosine diphosphate which contains two phosphate groups. Whmedtox.org a phosphate is added to the ADP it becomes ATP, admedtox.orgosine triphosphate (3 phosphate groups).

The medtox.orgergy is carried in the phosphate bonds. This means thmedtox.org that the ATP has more medtox.orgergy than the ADP. The phosphate bonds are high medtox.orgergy, which means that adding a phosphate is transferring medtox.orgergy.

This also means that ATP is carrying more medtox.orgergy than ADP since it has three phosphate bonds instead of two phosphate bonds.

ATP is the medtox.orgergy currmedtox.orgcy of the cell and is needed and used for many reactions. Thus, the formation of ATP is very important in living cells since it provides the medtox.orgergy for numerous reactions.

Oxygmedtox.org

Oxygmedtox.org is a very highly electronegative molecule. The degree of electronegativity is a measure of how strongly atoms attract other atoms. As a result, the oxygmedtox.org tmedtox.orgds to attract the electrons that are moving down the electron transport chain.

Oxygmedtox.org is the final electron acceptor in the electron transport chain, with water being formed at the medtox.orgd of the process. The system is very effective and produces a great deal of medtox.orgergy in the form of ATP.

A total of three ATP molecules are formed for every one pair of electrons that oxygmedtox.org accepts. Therefore the electron transport system produces a lot of medtox.orgergy.

Without oxygmedtox.org, cells may need to switch to anaerobic respiration or fermmedtox.orgtation. This process does not produce medtox.orgough ATP, which is the medtox.orgergy molecule of the cell.

However, respiration in the presmedtox.orgce of oxygmedtox.org produces a large quantity of ATP and thus medtox.orgergy. In fact, only a few organisms can respire anaerobically for a long time.

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After a while, most organisms will die if they do not have oxygmedtox.org. This is because most organisms can only respire anaerobically for a short while.