The class of nutrients that serves as a primary energy source for organisms is carbohydrates. These organic compounds are broken down during metabolic processes to release energy, which is essential for cellular functions like growth, repair, and maintenance. Carbohydrates include sugars and starches, which are stored in the body and converted into glucose, the primary fuel for cellular respiration. Their significance extends beyond energy provision, as they play roles in cell signaling, structure, and function. Overall, carbohydrates are crucial components of a balanced diet and metabolism.