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This has been bugging me for a while, and I can't seem to find an answer to it, and I am sorry if I am asking a lot with this question(s). Firstly, I keep finding sources suggesting that ethanol is osmotically active, but I also know that ethanol can enter the cell readily through passive diffusion, and some sources also say it uses transport proteins - what causes osmotically active behaviour, then? Secondly, and this is very closely linked to the above, why do cells shrink in the presence of ethanol of high concentrations, if it is able to enter readily, unlike, say, ions? The mechanism seems to be far more complex than I have found regarding simple osmosis for ions and such.

I would like to add that my confusion may also be due to conflicting information I am getting, whether the cell shrinks or grows (or does one then the other), so it is hard for me to even picture if the solution acts as if it is hyper- or hypotonic.

SECOND EDIT: Seems that there is evidence from some sources that suggest ethanol can affect the osmolarity of the solution without itself being "effective", whatever that means. Something to do with the lipid membrane. Again, I keep editing this so people might... possibly... have something to go off when answering this.

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  • $\begingroup$ I would also add this seems to be a similar case to urea, so answer would likely deal with that case as well. $\endgroup$ – Matthew John Jackman Nov 29 '17 at 4:08

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