What is the direction of movement in passive transport?

In passive transport, molecules move from areas of high concentration to areas of low concentration. This process occurs without the input of energy, as it relies on the natural kinetic energy of molecules. When substances move down their concentration gradient, they tend to spread out evenly in a solution, seeking equilibrium. This is a fundamental principle of diffusion, which is a common type of passive transport, alongside processes like facilitated diffusion and osmosis. In contrast, moving against the concentration gradient (from low to high concentration) requires energy input, which differentiates active transport from passive transport. Understanding this key concept helps clarify how substances can enter or exit cells efficiently without energy expenditure, maintaining cellular function and homeostasis.