Why is it important that energy-releasing reactions take place in living organisms?
It is it important that energy-releasing reactions take place in living organisms because living organisms need energy. These energy releasing reactions allow the cell to capture the energy released during oxidative metabolism and store it as potential chemical energy.
Living organisms run on biochemical reactions, and these reactions are affected by temperature. Any chemical compound is going to break down at a sufficiently high temperature, and any liquid (other than helium) is going to freeze solid at a sufficiently low temperature. Every organism has an certain temperature range in which it functions most successfully.