The term “down the concentration gradient” refers to the movement of molecules from an area of higher concentration to an area of lower concentration. This process is a fundamental concept in biology and chemistry, particularly in the context of diffusion and osmosis.
In simpler terms, imagine you have a container with two compartments divided by a semipermeable membrane. If one side has a high concentration of a substance, like sugar, and the other side has a low concentration, the sugar molecules will naturally move through the membrane to the side with lower concentration. This movement continues until the concentrations on both sides equalize.
This process doesn’t require any energy input; it happens naturally due to the random movement of molecules. Thus, moving down the concentration gradient is a passive transport mechanism, crucial for many biological processes, including nutrient absorption, gas exchange, and cellular respiration.