The electrons passing through the electron transport chain gradually lose energy, High-energy electrons donated to the chain by either N.A.D.H or FA.DH2 complete the chain, as low-energy electrons reduce oxygen molecules and form water. The end products of the electron transport chain are water and A.T.P..
Explanation: Photosynthesis removes CO2 from the atmosphere and replaces it with O2. Respiration takes O2 from the atmosphere and replaces it with CO2.
