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Osmosis help needed!

So I understand that a Hypertonic solution has a LOW water potential so water will move OUT of the cell, but what I don't understand is that if osmosis is the movement of water molecules from an area of high water potential to an area of low water potential, then why would it move out of the cell if it has a low water potential... i am just very confused right now and can't get my head around it
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Avatar for Maden222
Maden222
Original post by alaskalost
So I understand that a Hypertonic solution has a LOW water potential so water will move OUT of the cell, but what I don't understand is that if osmosis is the movement of water molecules from an area of high water potential to an area of low water potential, then why would it move out of the cell if it has a low water potential... i am just very confused right now and can't get my head around it


Hypertonic = High water potential, not low. Hypotonic = low water potential.
water potential and concentration are two different things i think you are getting them mixed up

think of it as
if you have high water potential you would have low concentration as most of the molecules are water and less of them are the substance
Original post by Maden222
Hypertonic = High water potential, not low. Hypotonic = low water potential.


Incorrect. Hypertonic solutions have a higher concentration of solutes and thus a lower water potential.

Original post by alaskalost
So I understand that a Hypertonic solution has a LOW water potential so water will move OUT of the cell, but what I don't understand is that if osmosis is the movement of water molecules from an area of high water potential to an area of low water potential, then why would it move out of the cell if it has a low water potential... i am just very confused right now and can't get my head around it


A hypertonic solution has a low WP. The WP in a cell bathed in a hypertonic solution is higher than that of the surrounding solution. Thus water moves osmotically from high to low WP from the cell to the outside causing possible crenation.
(edited 8 years ago)
Reply 4
Avatar for Gogregg
Gogregg
14
Osmosis is the movement of water from an area of high concentration of water, to an area of low concentration.

It is also the movement of water from a less negative to a more negative water potential. (Low to high)

The terms get a bit confusing, but the other answers explain it well :smile:
Reply 5
Avatar for kaz297
kaz297
1
Original post by alaskalost
So I understand that a Hypertonic solution has a LOW water potential so water will move OUT of the cell, but what I don't understand is that if osmosis is the movement of water molecules from an area of high water potential to an area of low water potential, then why would it move out of the cell if it has a low water potential... i am just very confused right now and can't get my head around it


If the solution is hypertonic, it means there is lots of solutes present (therefore the water potential is low).

The cell (which is surrounded by this hypertonic solution), has a lower amount of solutes and therefore a HIGHER water potential.

That is why the water will move from a region of high to low water potential. (Remember inside the cell, the water potential is closer to 0, the outside will be MORE negative).

Hope this helps.

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