What is the importance of O2 in aerobic respiration?1 pointIt is an electron acceptor at the end of the electron transport chain.It is mixed with H+ molecules to form water in the formation of ATP.It is released as a by-product in the process of photosynthesis.It combines with acetyl-CoA at the start of the Calvin cycle.Clear selection

The importance of O2 (oxygen) in aerobic respiration is that it acts as the final electron acceptor at the end of the electron transport chain. During aerobic respiration, electrons are passed along the electron transport chain, with each transfer releasing energy. This energy is used to pump protons across the inner mitochondrial membrane, creating a proton gradient. The protons then flow back across the membrane, driving the synthesis of ATP (adenosine triphosphate), the main energy currency of cells.

At the end of the electron transport chain, the electrons are transferred to oxygen. This reaction also involves protons, resulting in the formation of water. Without oxygen to accept the electrons, the electron transport chain would stop working, and ATP production would cease. Therefore, oxygen is crucial for energy production in aerobic organisms.

The other options mentioned in the question are not correct. Oxygen does not mix with H+ molecules to form water in the formation of ATP, it is not released as a by-product in the process of photosynthesis (that would be O2), and it does not combine with acetyl-CoA at the start of the Calvin cycle. The Calvin cycle is part of photosynthesis, not aerobic respiration, and it involves the fixation of carbon dioxide, not oxygen.