NEET BIOLOGY

Detailed explanation-1: -A concentration gradient occurs when the concentration of particles is higher in one area than another. In passive transport, particles will diffuse down a concentration gradient, from areas of higher concentration to areas of lower concentration, until they are evenly spaced.

Detailed explanation-2: -The concentration gradient provides the energy (entropic energy) that drives the net movement of molecules from one side of the membrane to the other.

Detailed explanation-3: -For diffusion to occur there must be a concentration gradient. The dissimilarity in the amounts of solutes, particles, or molecules between the two regions will cause them to move between the two regions.

Detailed explanation-4: -Living cells need certain substances in concentrations greater than they exist in the extracellular space. Moving substances up their electrochemical gradients requires energy from the cell. Active transport uses energy stored in ATP to fuel the transport.