Question

Which of the following occurs while electrons travel down the electron transport chain during the light reactions of photosynthesis in chloroplasts?

a) ATP synthase pumps protons into the thylakoid space to generate ATP
b) The pH of thylakoid space drops as protons are transported across the thylakoid membrane from the stroma, forming a proton gradient
c) Cytochrome complexes transfer protons out of the thylakoid acidifying the stroma
d) NADP+ is oxidized by NADP+ reductase to form NADPH

Answer 1

During the light reactions of photosynthesis in chloroplasts, electrons traveling down the electron transport chain result in a lower pH in the thylakoid space, the generation of ATP, and the production of NADPH.

Step-by-step explanation:

During the light reactions of photosynthesis in chloroplasts, the movement of electrons down the electron transport chain leads to the following:

1. The pH of thylakoid space drops as protons are transported across the thylakoid membrane from the stroma, forming a proton gradient. The movement of electrons down the electron transport chain pumps protons from the stroma to the thylakoid space, resulting in a lower pH in the lumen compared to the stroma.
2. As the protons are moved from the stroma to the thylakoid space, ATP synthase pumps the protons back into the stroma, generating ATP.
3. At the same time, NADP+ is reduced to form NADPH through the action of NADP+ reductase. This reduction reaction removes protons from the stroma.