2.5.A—Describe the mechanisms that organisms use to maintain solute and water balance

Describe the mechanisms that organisms use to maintain solute and water balance.

• The selective permeability of membranes allows for the formation of concentration gradients of solutes across the membrane.
• Passive transport is the net movement of molecules from regions of high concentration to regions of low concentration without the direct input of metabolic energy.
• Active transport requires the direct input of energy to move molecules. In some cases, active transport is utilized to move molecules from regions of low concentration to regions of high concentration.