10. proteins enable a cell to sense its surroundings by binding to certain substances outside the cell. 11. To reach equilibrium, substances always flow from an area of high concentration to an area of concentration.
12. When one area has a higher concentration than another area does, a concentration exists.
13. Diffusion of ions through ion channels is a form of transport.
14. A cell does not expend when diffusion takes place.
15. The diffusion of through cell membranes is called osmosis.
16. When the concentration of free water molecules is higher outside a cell than inside the cell, water will diffuse the cell.