<P> This consumes the H ions produced by the splitting of water, leading to a net production of 1 / 2O, ATP, and NADPH + H with the consumption of solar photons and water . </P> <P> The concentration of NADPH in the chloroplast may help regulate which pathway electrons take through the light reactions . When the chloroplast runs low on ATP for the Calvin cycle, NADPH will accumulate and the plant may shift from noncyclic to cyclic electron flow . </P>

Where does the hydrogen ion concentration gradient form in photosynthesis