Why do organisms that release energy through aerobic respiration need oxygen

glucose is broken down by oxygen to release energy with carbon dioxide and water being produced as by-products of the reaction. ... The released energy is used to make a special energy molecule called Adenosine triphosphate (ATP).

Oxygen is the final "link" in the electron transport chain because it has the highest electronegativity and affinity for electrons. This final link is key because it allows the NADH and FADH₂'s to dump their electrons and return to being NAD+ so they can pick up electrons in glycolysis and the citric acid cycle. Without oxygen, the system becomes backed up and the electron transport chain can not produce ATP (which accounts for 34 of 38 of them from a single glucose molecule).

A: rachel carson :

The hawk receives 0.1% energy from the caterpillar although the caterpillar gets eaten by another bird smaller than the hawk first