At the same time, carbon dioxide molecules diffuse rapidly out of the red blood cells<span>, down their concentration gradient, and into your lungs. When </span>water<span> molecules </span>move <span>freely </span>across a cell membrane<span>, the process is called OSMOSIS , which is just a special type of simple diffusion.</span>
Streams or rivers form when water that does not find an underground aquifer, drains off the land by either seeping through the soil or spilling over the surface into the river or stream bed.
