Hi! I have been given an assignment to do which involves writing about the roles Oxygen and Carbon Dioxide play in sustaining life on earth. I have done most of it but one section has stumped me.
I have to include specific acid/base reactions and redox reactions relating to life and a specific stoichiometric calculation using one of the selected reactions involving the sustaining of life.

What could be a redox reaction relating to life? As in a redox reaction which occurs in nature that aids in the supporting of life on earth.
Also what could be an acid/base reaction also relating to supporting life?

I was thinking that I would use photosynthesis as the redox reaction, but this seems a bit obvious, are there any others?
i.e. Photosynthesis:
6CO₂ + 6H₂O ---> C₆H₁₂O₆ + 6O₂

This is necessary for life because it produces Oxygen which we all need to live.


Thanks in advance for any help =P

Another important redox reaction is cellular respiration (glucose + oxygen + ADP + Pi --> carbon dioxide + water + ATP), which allows organisms to produce energy.

As for acid-base reactions (although this isn't exactly a standard acid-base reaction), here's a pretty useful one for humans:

CO₂ + 2H₂O <--> HCO₃^- + H₃O⁺

This reaction (the bicarbonate buffer reaction) is important because 1) it helps keep blood at the correct pH and 2) it allows blood to transport CO₂ from cells in the body to the lungs.

Yes, glucose is oxidised whilst oxygen is reduced, you are correct.

As for acid-base reactions (although this isn't exactly a standard acid-base reaction), here's a pretty useful one for humans:

CO₂ + 2H₂O <--> HCO₃^- + H₃O⁺

This reaction (the bicarbonate buffer reaction) is important because 1) it helps keep blood at the correct pH and 2) it allows blood to transport CO₂ from cells in the body to the lungs.

Hi, again, I googled bicarbonate buffer reactions, and the stuff i found either wasnt helpful or was too advanced for my understanding.  
Could you please explain what happens during this reaction? In what part of the body it occurs? What would happen if it didn't/couldn't occur?
Also, are you sure that is the equation? A site i found gave the following equation:

H3O + HCO3 <-> H2CO3 + H2O <-> 2H2O + CO2

And stated that only the first part is an acid/base reaction. i.e. only
H3O + HCO3 <-> H2CO3 + H2O is an acid base reaction. Which gets me confused.
Any help would be greatly appreciated.

Thanks again.

EDIT:
I found out what would happen if it didnt occur, the body would go into a state of metabolical acidosis, which can result in coma and death.
So you weren't joking when you said that its pretty useful!  

Since metabolic activity produces carbon dioxide, the transport of bicarbonate ions helps to remove carbon dioxide from the body, since the lungs remove carbon dioxide from the blood.

So does it transport the carbon dioxide from cells in the body into the lungs which then remove it from the body (when you exhale) or does it remove the CO₂ in some other way?

Also, I need to write a stoichiometric equation involving one of the given reactions; i have included the following reactions:
Photosynthesis
6H₂O + 6CO₂ + light ? C₆H₁₂O₆ + 6O₂

Energy from glucose and oxygen (in the body)
C₆H₁₂O₆ + 6O₂ ? 6CO₂ + 6H₂O + energy

and
Carbonic-acid-Bicarbonate Buffer equation
H₃O⁺ + HCO₃^- <--> H₂CO₃ + H₂O <--> 2H₂O + CO₂

I would prefer to do a stoichiometric equation using the carbonic-acid-bicarbonate buffer equation but I cant get any measurements of (for example) the average amount of CO₂ produced. etc.
Which equation do you think will suite my needs the best? What should I solve using stoich.?

Thanks

Im pretty sure that the numbers do have to be real, and yes I have to take a certain number of reactant and calculate how much product ill create. So using the carbonic-acid-bicarbonate buffer reaction, if i had (for example) how much carbon dioxide & water was produced i could figure out how much carbonic acid is used to create that much carbon dioxide etc.
Or if all else fails (i cant do a stoichiometry equation with the buffer) i could do a stoichiometry equation using photosynthesis. To show how much glucose is produced using a certain amount of water and carbon dioxide.