Biologyquestions
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I know its because both reduction and oxidation take place, but what exactly is reduced and oxdised?
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Laurasaur
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(Original post by Biologyquestions)
I know its because both reduction and oxidation take place, but what exactly is reduced and oxdised?
Oxygen is oxidised, carbon is reduced.

6CO2 + 6H2O --> C6H12O6 + 6O2

Oxidation states:
In carbon dioxide, O=-2, C=+4
In water, H=+1, O=-2
In glucose, C=0, H=+1, O=-2
In oxygen, O=0
So the oxidation state of carbon has reduced from +4 to 0, this is reduction.
The oxidation state of oxygen has increased from -2 to 0 (as O2), this is oxidation.
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PlayerBB
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(Original post by Biologyquestions)
I know its because both reduction and oxidation take place, but what exactly is reduced and oxdised?
Are you taking A2 biology ?


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Biologyquestions
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(Original post by PlayerBB)
Are you taking A2 biology ?


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Yep
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mercuryman
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in simple terms: h20 is broken down into 02, 2H+ and 2e-. Electrons are carried by electron acceptors on thylakoid membranes. These e-s are passed down to other electron acceptors on the membrane. these charged electrons reduce electron acceptors when they obtain them and oxidise the electron acceptors that pass this e-. Overall you'd get redox reactions occurring on these thylakoid membrane proteins ( in the light dependant reaction!)

hope this helped
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mercuryman
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(Original post by Biologyquestions)
Yep
Are you doing a2 snab bio by any chance?

if so, I made a -->thread<-- Specifically for A2 bio! (you can still ask bio qs regardless of your exam board tbh its all the same )
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PlayerBB
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(Original post by Biologyquestions)
Yep
Then I assume you're familiar with cyclic phosphorylation, non-cyclic phosphorylation, and the calvin cycle! Well if you think about it, in all of these there is an electron removed and added back again resulting in a redox reaction in each cycle, for example, in cyclic phosphorylation, when the light hit the chlorophyll in the photosystemI , an electron gets excited and jumps off to a higher energy level and then is carried by an electron receptor then this electron goes back to the chlorophyll after some stages so this is an example of a redox reaction that occurs in the photosynthesis process

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PlayerBB
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Anyone doing A2 biology Edexcel 8BI01-9BI01 or IAL edexcel biology, feel free to join the thread that I have made
http://www.thestudentroom.co.uk/show....php?t=3892553

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Kflexman
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(Original post by Biologyquestions)
I know its because both reduction and oxidation take place, but what exactly is reduced and oxdised?

Not sure exactly why, but pretty much any reaction that occurs is redox because reduction and oxidation refer to the gain and loss of electrons by species, and if one species loses electrons, another must gain them, as the electrons must go somewhere.

Also, photosynthesis is a lot more than just '6CO2 +6H2O--> C6H12O6 + 6H2O'.

There are loads of intermediates and steps, all involving reduction and oxidation. For example NADP+ is reduced at the end of the electron transport chain to form NADPH. And NADPH is oxidised in the Calvin Cycle.


It's difficult to talk about the Chemistry behind Biological concepts due to the fact Biology oversimplifies things, especially at a pre-university level.


Sorry I haven't really helped much but yeah...
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