Why is energy required for active transport?

Energy is required for active transport because it moves substances against their concentration gradient, from a lower to a higher concentration.

Active transport is a process that enables cells to move substances across the cell membrane from an area of lower concentration to an area of higher concentration. This is contrary to passive transport, which allows substances to move along their concentration gradient, from an area of higher concentration to an area of lower concentration, without the need for energy.

The energy required for active transport is usually in the form of adenosine triphosphate (ATP), the main energy currency of the cell. This energy is used to change the shape of the transport protein, allowing the substance to be moved across the membrane. The protein then returns to its original shape, ready to transport another molecule.

Active transport is crucial for maintaining the balance of ions and molecules inside and outside the cell, which is essential for the cell's survival and function. For example, the sodium-potassium pump, a type of active transport, maintains the electrochemical gradient necessary for nerve impulse transmission.

In summary, active transport requires energy because it is working against the natural diffusion of substances, moving them from an area of lower concentration to an area of higher concentration. This energy-intensive process is vital for many cellular functions and the overall homeostasis of the organism.