What allows sodium and potassium ions to diffuse down their electrochemical gradient across the cell membrane?

Which of the following statements about diffusion is true?

A patient is admitted to the hospital and given intravenous (IV) fluids. Four hours later, the patient complains that his mouth and eyes feel dry. You notice that he displays signs of dehydration, and when you check his IV, you see that he was given the wrong kind of fluids. Were these fluids likely hypotonic, isotonic, or hypertonic? Explain.

A hypotonic solution will cause water to move ________the cell, and the cell will ______.

A hypertonic solution will cause water to move ______the cell, and the cell will ________.