What is the final electron acceptor og the electron transport chain?

The electron transport chain refers to the transfer of electrons from electron donors and electron acceptors. After the transfer of electrons, these electrons then couple with protons (H+ ions) across a membrane. In eukaryotic cells, electron transport chains occur within the mitochondrial membrane where it serves as the site of oxidative phosphorylation that uses ATP as its energy source.  

The molecular oxygen is the final acceptor of electrons in an electron transport chain. This type of transport is used by the cell in extracting energy through redox reactions that occur during photosynthesis, sugar oxidation, and cellular respiration.