Final answer:
Catabolic reactions utilize energy, breaking down large organic molecules into smaller ones and releasing energy. This process helps provide the necessary energy for cellular functions.
Step-by-step explanation:
Catabolic reactions utilize energy and give simpler compounds, whereas in anabolic reactions, energy is produced and simpler compounds are used to make complex molecules.
Because catabolic reactions produce energy and anabolic reactions use energy, ideally, energy usage would balance the energy produced. If the net energy change is positive (catabolic reactions release more energy than the anabolic reactions use), then the body stores the excess energy by building fat molecules for long-term storage. On the other hand, if the net energy change is negative (catabolic reactions release less energy than anabolic reactions use), the body uses stored energy to compensate for the deficiency of energy released by catabolism.
Catabolic reactions break down large organic molecules into smaller molecules, releasing the energy contained in the chemical bonds. Approximately 40 percent of energy yielded from catabolic reactions is directly transferred to the high-energy molecule adenosine triphosphate (ATP), which can be used immediately to power cellular functions. The remaining 60 percent is given off as heat.