Final answer:
The reaction ADP + Pi → ATP represents an endergonic reaction, requiring energy to proceed. This is contrasted by exergonic reactions such as ATP → ADP + Pi, which release energy, typically found in processes like cellular respiration and catabolic reactions. so, option D is the correct answer.
Step-by-step explanation:
An endergonic reaction is one in which energy is absorbed from the surroundings; the products of the reaction have more energy than the reactants. The endergonic reactions typically involve synthesis and are not spontaneous without an input of energy. In contrast, an exergonic reaction is one where energy is released and the products have less energy than the reactants; these often occur spontaneously.
Out of the given options, ADP + Pi → ATP represents an endergonic reaction because it requires an input of free energy to proceed. This process is used by cells to store energy, and this stored energy is later used to drive endergonic reactions in the cell. On the other hand, ATP hydrolysis, represented by ATP → ADP + Pi, is an exergonic reaction as it releases energy.
During glycolysis, in the second half of the process, ATP is produced. Glycolysis converts one molecule of glucose into two molecules of pyruvate with a net gain of two ATP molecules after the initial investment of two ATP.
Identifying reactions according to their energy changes: A. Cellular respiration - exergonic. B. Photosynthesis - endergonic. C. Catabolic reactions - exergonic. D. Anabolic reactions - endergonic.