Summary
The diffusion of water across a selectively permeable membrane from lower to higher solute concentration.
In depth
Water moves from a region of higher water potential to lower water potential across a semipermeable membrane. It is driven by solute concentration, so water goes toward the more concentrated solution.
In plants water potential is the sum of solute potential (always negative) and pressure potential. Cells in pure water gain water until the wall pressure stops further uptake, becoming turgid.
Frequently asked questions
What is Osmosis?
The diffusion of water across a selectively permeable membrane from lower to higher solute concentration.
Which area of biology covers Osmosis, and how advanced is it?
Osmosis is one of the 52 topics in Cell Biology. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Cell Wall, Facilitated Diffusion, Simple Diffusion.
Can you give an example of Osmosis?
Salting slugs or pickling food works because water is pulled out of cells by the strong external solution.
What should I learn before Osmosis?
Work through the Beginner topics in Cell Biology first, such as Cell Theory, Prokaryotic Cell, Eukaryotic Cell, then return to Osmosis. Intermediate topics assume the Beginner vocabulary.
What topics are related to Osmosis?
The closest topics to Osmosis are Cell Wall, Facilitated Diffusion, Simple Diffusion, Tonicity. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Osmosis?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Osmosis. To practise the whole of Cell Biology, use the Cell Biology quiz.
How is Osmosis different from Cell Wall?
Osmosis: The diffusion of water across a selectively permeable membrane from lower to higher solute concentration. Cell Wall: A rigid outer layer outside the plasma membrane in plants, fungi and bacteria that gives shape and protection. Read both side by side and note what each one explains.
How should I study Osmosis step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Cell Wall and explain the difference aloud. Finally, take the Cell Biology quiz and come back to this page for any question you miss.