Question

What uses excited electron energy to pump protons across the thylakoid membrane?

a) Photosystem I
b) Photosystem II
c) ATP synthase
d) Calvin cycle

Answer 1

Photosystem II is responsible for using the excited electron energy to pump protons across the thylakoid membrane, contributing to the generation of ATP and NADPH for the Calvin cycle.

Step-by-step explanation:

The process that uses excited electron energy to pump protons across the thylakoid membrane is attributed to photosystem II. When photons strike photosystem II, pigments pass the light energy to chlorophyll a molecule that excites an electron. This electron is then passed to the electron transport chain. During this process, the cytochrome complex transfers protons across the thylakoid membrane and transfers electrons from photosystem II to photosystem I. This proton gradient drives ATP synthesis, and the electrons eventually contribute to the formation of NADPH. Both ATP and NADPH are then utilized in the Calvin cycle to produce glucose.