Which type of reaction requires energy input?

An endergonic reaction is one that requires an input of energy for the reaction to proceed. This type of reaction is characterized by a positive change in Gibbs free energy, meaning that the energy of the products is higher than that of the reactants. As a result, energy must be supplied from an external source for the reaction to occur.

In biological systems, endergonic reactions are essential for processes such as photosynthesis and the synthesis of macromolecules like proteins and nucleic acids. These reactions often involve the coupling of energy-releasing processes (like the breakdown of ATP) to provide the necessary energy for the endergonic reactions.

Understanding this principle is crucial when studying metabolism and energy transformations within living organisms, as it highlights how energy input is necessary for certain biological functions and the synthesis of complex molecules.