2.7.A—Explain how concentration gradients affect the movement of molecules across membranes

Explain how concentration gradients affect the movement of molecules across membranes.

• External environments can be hypotonic, hypertonic, or isotonic to internal environments of cells. Movement of water can also be described as moving from hypotonic to hypertonic regions. Water moves by osmosis from regions of high water potential to regions of low water potential. Relevant equation: Water Potential: ps where: p = pressure potential s = solute potential