plants use the proton electrochemical gradient across the vacuole membrane to power the accumulation of salts and sugars in the organelle. this creates a hypertonic situation. why does this not result in the plant cell swelling and bursting? even under isotonic conditions there is a slow leakage of ions into animal cells. how does the plasma membrane Na+/ K+ ATPase enable animal cells to avoid osmotic lysis under isotonic conditions?