Where do the electrons that enter the electron transport chain come from?

Last week i was assigned a thematic. we have groups of three but the people i was assigned with haven't been in school for days. i would appreciate if anyone can me with my thematic . i highlighted most of the important steps and i circled my thematic topic. in desperate need : ( its due on february 19

What type of organism is a one-celled organism that functions as a single unit? a. bi-celled b. single-celled c. pre-celled d. multi-celled

Is a fossil fem that support wegener's hypothesis of continental drift a. gondwanded b. kannemerid c. mesosaurus d. glossopters