The primary biological role of carbohydrates in living organisms is to serve as a key source of energy. They are primarily composed of carbon, hydrogen, and oxygen, and are found in forms such as glucose, starch, and cellulose. Carbohydrates provide energy for cellular processes, support cellular structures, and play vital roles in cell signaling. Additionally, they can serve as storage molecules, helping to regulate energy availability, especially in plants and animals. Their importance extends beyond energy metabolism, influencing various biochemical pathways essential for maintaining life.