Difference between Active and Passive Transport
Active and Passive transport are biological transport processes that involve transport of molecules across the cell membrane of cells in living organisms. A cell membrane is a semipermeable membrane that surrounds the cell and separates its cytoplasm (contents of the cell) from the extracellular environment. Let us see how Active transport differs from Passive transport.
Active transport is the movement of molecules across the membrane against the concentration gradient (from a region of lower concentration to a region of higher concentration) using cellular energy in the form of ATP. It is called ?active? because it involves the use of energy, e.g. energy is used by the cell in the form of ATP (Adenosine Triphosphate) to carry out movement of substances into the cell through cellular membrane. Endocytosis, exocytosis, sodium-potassium pump are few examples of active transport.
Active transport can be of two types: primary active transport and secondary active transport. When the active transport occurs using cellular energy in the form of ATP it is known as primary active transport. The active transport in which proteins in the cell membranes uses an electrochemical gradient to move molecules across the membrane is called secondary active transport. The energy comes from the electrochemical gradient created by pumping ions out of the cell.
Passive transport is the movement of molecules across the membrane along the concentration gradient, from high to low concentration, without using cellular energy. In passive transport, a substance tends to diffuse from a region of higher concentration to a region of lower concentration.
It occurs spontaneously so it does not require cellular energy. In passive transport natural entropy is used to move molecules from their higher concentration to lower concentration until equilibrium is achieved.
Easy soluble particles are transported through passive transport, e.g. wastes like water or carbon dioxide are moved out, and nutrients and oxygen are moved into the cells through passive transport. Its common examples include diffusion, osmosis, and facilitated diffusion.
Based on the above information, some of the key differences between active transport and passive transport are as follows: