The term for the movement of substances against their concentration gradient using energy is known as active transport. This process requires energy, often derived from ATP, to transport molecules from areas of lower concentration to areas of higher concentration. Active transport is essential for maintaining homeostasis within cells, allowing them to accumulate necessary nutrients, ions, or other substances for metabolism, even when these substances are less concentrated outside the cell. Active transport plays a significant role in various biological processes, including nerve impulse transmission and muscle contraction.