Wikipedia has a kind of contradiction that I would like to understand:
According to this link
The C3 pathway requires 18 ATP for the synthesis of one molecule of glucose while the C4 pathway requires 20 ATP. [...]
According to this other link:
[...]. The C3 pathway requires 18 molecules of ATP for the synthesis of one molecule of glucose, whereas the C4 pathway requires 30 molecules of ATP.[...]
Also, I don't understand much of this, I was just curious. I found this link (not sure if reduction also means generate glucose):
However, the C4 pathway of CO2 reduction expends more energy (5 ATP and 2 NADPH) than C3 pathway (3 ATP and 2 NADPH) (Hopkins 1999).
And this link:
ATP consumed in C4 plants
C4 cycle ( which involves regeneration of PEP from C3 acid) - requires 2 ATP per CO2 fixed.
C3 cycle ( which is common in C2,C3,C4 cycle)- requires 3 ATP per CO2 fixed.
Total - 5 ATP per CO2 fixed.
Thus to form a hexose or to fix 6 CO2 6*5= 30 ATP
All emphasis mine.
So... Does C4 requires 20 or 30 ATP per molecule of glucose? I think I found more evidence over 30 than 20, is that correct?