(a)Define Isotonic solutions. What happens if the saline solution concentration is (i) greater, (ii) less than 0.9 percent (mass/volume) NaCl?

(a) Isotonic solutions are solutions that have the same osmotic pressure as some other solution, especially one in a cell or a body fluid. In other words, they have the same concentration of solutes as the inside of the cell, which means there is no net movement of water into or out of the cell if it is placed in an isotonic solution.

(i) If the saline solution concentration is greater than 0.9 percent NaCl, it is considered hypertonic. In this case, the solution has a higher concentration of solutes than the inside of the cell. This causes water to move out of the cell to try to equalize the concentration, which can cause the cell to shrink or even die.

(ii) If the saline solution concentration is less than 0.9 percent NaCl, it is considered hypotonic. In this case, the solution has a lower concentration of solutes than the inside of the cell. This causes water to move into the cell to try to equalize the concentration, which can cause the cell to swell and possibly burst.