Final answer:
Cells expend substantial energy to maintain an organized state necessary for growth, reproduction, and homeostasis, which includes building complex molecules from simpler ones and managing waste.
Step-by-step explanation:
When a cell uses substantial energy to organize its contents to a greater extent than the external environment, it is involved in processes vital for growth, reproduction, and dynamic homeostasis. These processes require cells to create and maintain conditions internally that are different from their surroundings. To achieve this, living cells require energy for various tasks such as synthesizing molecules, moving them around the cell, and communicating with other cells via signaling molecules.
Cells must efficiently manage the energy released during catabolism to store it safely and release it when needed. Complex carbohydrates, for instance, break down into simpler sugars which the cell uses for energy, and large proteins are actively built from smaller molecules using energy. The constant flux of synthesizing and breaking down molecules, moving materials, and managing waste products underscores the significant energy demand placed on cells to maintain order and function effectively within the living organism.