Online College Courses for Credit



Author: Nathan Lampson

This lesson explains the process of osmosis. It explains how osmosis is a passive form of transport, used to move water molecules across a semi-permeable membrane, down their concentration gradient.

See More
Fast, Free College Credit

Developing Effective Teams

Let's Ride
*No strings attached. This college course is 100% free and is worth 1 semester credit.

47 Sophia partners guarantee credit transfer.

299 Institutions have accepted or given pre-approval for credit transfer.

* The American Council on Education's College Credit Recommendation Service (ACE Credit®) has evaluated and recommended college credit for 33 of Sophia’s online courses. Many different colleges and universities consider ACE CREDIT recommendations in determining the applicability to their course and degree programs.




the movement of water molecules through  a semi-permeable membrane.

Osmosis is considered a mode of passive transport because it does not require any energy.


Concentration Gradient

fewer molecules on one side of a membrane than on the other side of a membrane



When there is a higher concentration of water molecules on one side of a membrane.

More water molecules move from the side with a high concentration to the area with a low concentration of water.

Source: Concepts in Biology Twelfth Edition Eldon Enger, et al.