NADH and FADH2 are necessities in the electron transport chain because they power the chain by moving electrons into it.
NADH and FADH2 are both generated at the initial stages of respiration (the Kreb's cycle), a process during which food materials are broken down to generate energy. NADH is generated from NAD+ as a result of the addition of electrons while FADH2 is generated from FAD also due to the addition of electrons.
Once generated, both compounds get transferred into the innermost membrane of the mitochondrion where they travel down the electron transport chain, donating their electrons in the process and creating an electrochemical gradient to generate ATP.
Without NADH and FADH2, there will not be electrons to power the electron transport chain and the generation of ATP would become impossible.
More about the electron transport chain can be found here: brainly.com/question/13975046
