Exergonic reactions refer to those that are prone to losing energy whenever the reaction occurs. Activation energy is what facilitates such reactions to occur. Exergonic reactions can also be termed as exothermic, and these include oxidation, glycolysis, cellular respiration and fatty acid catabolism.
Reactions such as the synthesis of starch from sugar molecules are not exergonic. Photosynthesis is also not an endergonic reaction since the temperature of the sorrounding decreases whenever the process occurs. The melting of ice into water is also not exergonic.
Generally, in exergonic reactions, free energy of products is usually lower than that of the reactants, whereas in endergonic reactions, the free energy of the products is usually higher compared to that of the reactants