What is the term for a reaction that releases energy?

• A. Endergonic reaction
• B. Exothermic reaction
• C. Exergonic reaction
• D. Catalytic reaction

Answer: (C)

The term for a reaction that releases energy is best described as an exergonic reaction. In biochemical terms, an exergonic reaction is characterized by a negative change in Gibbs free energy (ΔG < 0), indicating that the products of the reaction have lower energy than the reactants. This release of energy can manifest in various forms, such as heat, light, or work, depending on the specific reaction.

Exergonic reactions are essential in biological systems as they often drive processes that require energy input, such as the synthesis of ATP from ADP and inorganic phosphate. The energy released can be harnessed to perform work in the cell, making these reactions crucial for maintaining life.

In contrast, other types of reactions, like endergonic reactions, absorb energy (ΔG > 0), making them less favorable in spontaneous processes. While exothermic reactions specifically refer to reactions that release heat, not all exergonic reactions are exothermic because they may release energy in forms other than heat. Catalytic reactions involve the use of catalysts to speed up reactions without altering the energy release, rather than defining the energy characteristics of the reaction itself.