If the concentration of solute molecules outside a cell is lower than the concentration in the cytosol, is the external solution hypotonic, hypertonic, or isotonic to the cytosol?
A hypotonic environment would mean that the concentration of solute is higher inside the cell than outside, or that the concentration of solvent (usually water) is higher outside the cell. Typically in hypotonic environments, water will move into the cell by osmosis and cell lysis occurs if the concentration gradient is too high.
Hypertonic: concentration of solute is higher outside the cell
Isotonic: concentration of solute is equal with the cell
Think of these terms by their prefixes- hypo = "under" hyper = "over" iso = "equal".