List the three types of environments that can be found outside of cells.  Include a brief description of each environment. Biology 12

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shoomie eNotes educator| Certified Educator

I think you might be asking about the 3 different osmotic conditions a cell might find itself in.  Isotonic is the normal cell environment where water moves in and out of the cell freely and equally in both directions.  It is in osmotic equilibrium so to speak.  The concentration of water and solutes is equal on both sides of the cello membrane.  In a hypotonic solution the cell will gain water and swell up - just like the letter O.  This means that the water concentration outside the cell is higher than inside the cell and the water moves into the cell.  It also means that the solute concentration is higher inside the cell than outside which causes the water to enter to try to dilute the solutes.  I'll bet you can guess what happens in the hypertonic solution.  The water exits the cell, the cell shrivels up.  This is due to the concentration of water inside the cell being higher than outside the cell and the concentration of solutes outside the cell being higher than inside the cell.  The definitions textbooks provide actually just refer to the solutes, but I like to relate it to water because it makes more sense to me.  You might go to youtube and search for osmosis - I believe there are movies there to watch the process.  I attached a couple of youtube sites to watch.