AQA A2 Biol4 January 2012 pre- exam discussion

Yeap, its to do with the pumping etc.

Yes it does.
Gaining of hydrogen = Reduction
Loss of hydrogen = Oxidation.
Gain of electrons = Reduction
Loss of electrons = Oxidation
Gain of oxygen = Oxidation
Loss of oxygen = Reduction

This is why when in the light-dependent stage, electrons that are transferred to 'NADP' reduce it, as well as the H+ from photolysis of water. They both cause a reduction in NADP.

I see. But if just lets say a loss of electrons occurred but the hydrogen stayed the same, would the 'molecule' whatever it may be still become oxidised?

Thanks for the help

Sorry don't quite understand what you said here? Do you mean there is a question on chemiosmosis? If so can you tell me which paper it's in, thanks

Fantastic
+Rep

Happy days, thanks

I cant remember.. maybe the june 2010?
It said describe the role of the inner membrane or something in producing ATP

Basically you just gotta know that in the Electron transport chain for respiration, as electrons are passed down it, carriers etc, they lose energy. This energy is used to pump H+ ions into the intermembrane space of the mitochondria, this causes a electrochemical gradient to be established, so H+ ions then go back into the matrix via protein carriers etc, and with ATP synthase --> ADP combines with Pi to form ATP.

I cant remember.. maybe the june 2010?
It said describe the role of the inner membrane or something in producing ATP

Basically you just gotta know that in the Electron transport chain for respiration, as electrons are passed down it, carriers etc, they lose energy. This energy is used to pump H+ ions into the intermembrane space of the mitochondria, this causes a electrochemical gradient to be established, so H+ ions then go back into the matrix via protein carriers etc, and with ATP synthase --> ADP combines with Pi to form ATP.

So during the diffusion of H+ back into the matrix they lose energy which is used to combine ADP and Pi? Also where do the H+ come from originally? Cheers

They diffuse back into the stroma via the enzyme ATP synthase which combine ADP and Pi to create ATP.
The H+ comes from photolysis when the water (H2O) splits into 2H+, 2e- and half o2.

Sorry, in respiration (matrix is in mitochondria) during the electron transport chain there, is it the same for the ATP synthase? and where do the H+ come from?

For the electron transport chain in photosynthesis, does the rule of H+ ions being pumped across ATP synthase still apply?
My CGP guide says so but the Nelson Thornes book doesn't.

Anyone here have any of the unit 4 past papers prior to jan 2010 or know of any websites that has them?

When referring to limiting factors in the rate of photosynthesis is it acceptable to say light intensity or do you have to be more general and say light? Thanks