What mechanism moves substances from an area of low concentration to an area of high concentration and requires energy input?

The mechanism that moves substances from an area of low concentration to an area of high concentration and requires energy input is known as active transport. This process is essential for maintaining cellular homeostasis and involves the movement of ions or molecules against their concentration gradient.

Active transport relies on ATP (adenosine triphosphate) as its energy source, allowing cells to accumulate substances in higher concentrations than would be possible through passive processes. The most common example is the sodium-potassium pump, which moves sodium ions out of the cell and potassium ions into the cell, crucial for maintaining membrane potential and various cellular functions.

In contrast, passive transport and facilitated diffusion do not require energy and move substances down their concentration gradients—from high to low concentration. Endocytosis involves the intake of substances into the cell but does not specifically refer to the movement against the concentration gradient like active transport does.