During aerobic respiration, which of the following directly donates electrons to the electron transport chain at the lowest energy level?

Answer: FADH2 (flavine adenine dinucleotide) is the electron donor of the electron transport chain at lowest energy level.

Explanation:

Aerobic respiration is the process whereby cellular energy is produce by using oxygen.

Electron transport chain is series of complexes that involves the movement of electrons from one molecule to another in order to release energy. NADH and FADH2 are the two major electron donor in electron transport chain.

NADH2 enter the electron transport chain through glycolysis, transformation of pyruvate to acetylcoa and citric acid while The two NADH enter the electron transport chain through citric acid. NADH2 is a good electron donor, it donates at high energy level while FADH2 is not good at donating electron so it's donate electron at lowest energy level.