In photosynthesis, the electron that travels through the electron transport chain in the thylakoid membrane comes . in cellular respiration, a molecule of supplies the electron that travels through the electron transport 1 2 atp atp carbon dioxide carbon dioxide water water nadh nadh

Answers:
1) Water
2) NADH



1) Water donates the initial electron in photosynthesis. The process of photolysis splits the water into H+ and O2 (oxygen, a byproduct of photosynthesis), and releases electrons which are taken up by photosystem II.

2) The electron transport chain is in the last step of cellular respiration, oxidative phosphorylation. NADH donates the electrons, which are used to pump H+ against the gradient into the intermembrane space of the mitrochondria. These H+ flow back across the membrane through ATP synthase to generate ATP.