Why do people say that water moves into the cell because the water concentration of the cell sap is low ? the cell sap is surrounded by a membrane so if any water moves into the cell it must be because the concentration of water in the cytoplasm is lower than the surroundings. I am thinking that water from the cytoplasm moves into the cell sap solution and as a result , the concentration of water in the cytoplasm decreases so water moves in from the surroundings.

  • $\begingroup$ Maybe people use a bad shortcut of what en.wikipedia.org/wiki/Osmosis is? $\endgroup$ Nov 28, 2016 at 17:22
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    $\begingroup$ Is ytour question: "What is osmosis?" $\endgroup$
    – user27740
    Nov 28, 2016 at 20:05
  • $\begingroup$ though the situation is similar is same as osmosis in jars; Upvoted and watchlisted. Because one popular explanation for why "osmosis is sort of diffusion" tells; the "concentration of water" in an aq. solution of something; is lesser than concentration of "water" in pure water! because pure water is 100% water, but an aq. soln of something is not 100% water. So on presence of membrane; pure water (high conc of water) diffuse into soln (low water). But I couldn't accept it anymore when I came to know that, adding little salt to water make it contract (contd)... $\endgroup$
    – user25568
    Nov 29, 2016 at 9:47
  • $\begingroup$ ...(contd)... link so the concentration of water (moles per liter) actually increased still water would go to the salt side from pure-water side. It became clear only when it was explained to me with concept of free-energy changes in mixing. $\endgroup$
    – user25568
    Nov 29, 2016 at 9:50


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