Question

each pair of electrons is passed down the chain, dropping in _____ needed for active transport of H+ ions against their _____.

Answer 1

Dropping in energy levels

Against their concentration gradient

Step-by-step explanation:

The pair of electrons are passed down a series of electron carriers of progressively lower energy levels through a series of redox reactions in the electron transport chain, releasing energy (electrical potential energy) to be used by H+ pump for the active transport of H+ ions (aka protons) from a region of higher concentration to a region of lower energy level against its concentration gradient.