What does the term "endergonic" refer to in cellular reactions?

The term "endergonic" specifically refers to reactions that require energy input to proceed. In these reactions, the energy of the products is higher than that of the reactants, which means that energy must be absorbed from the surroundings to drive the reaction forward. This is often seen in processes like photosynthesis, where light energy is absorbed to convert carbon dioxide and water into glucose and oxygen. Therefore, understanding that endergonic reactions are characterized by their need for energy is crucial for comprehending their role in biological systems, where they facilitate the transformation of substrates into more complex molecules.