Define hypotonic, hypertonic, and isotonic. What would be the fate of an animal cell immersed in each of these three types of solution?

(This step involves providing clear definitions of the three types of solutions, which can guide the student in understanding their effects on animal cells.) A hypotonic solution is one in which the solute concentration outside the cell is lower than the solute concentration inside the cell. In other words, the solution surrounding the cell has fewer solutes or particles. A hypertonic solution is one in which the solute concentration outside the cell is higher than the solute concentration inside the cell. The solution surrounding the cell has more solutes or particles in this case. An isotonic solution is one in which the solute concentrations both outside and inside the cell are equal. There is no concentration gradient in this case, and the concentrations are at equilibrium.

(Now that we have defined the types of solutions, we can explain how an animal cell would behave in each one.) In a hypotonic solution, the solute concentration is higher inside the cell than outside. Since water molecules tend to move from areas of low solute concentration to areas of high solute concentration (a process called osmosis), the water will flow into the animal cell. As a result, the cell will swell and may eventually burst. This process is called cytolysis or osmotic lysis.

(In this step, we describe the behavior of an animal cell in a hypertonic solution.) In a hypertonic solution, the solute concentration is higher outside the cell than inside. Water will move out of the cell through osmosis because there is a higher concentration of solutes outside. As a result, the animal cell will lose water, causing it to shrivel or shrink. This process is called crenation or plasmolysis.

(Finally, we describe the impact of an isotonic solution on animal cells.) In an isotonic solution, the solute concentrations are the same both inside and outside the cell. Water molecules will move in and out of the cell at the same rate, resulting in no net movement of water. This means that the animal cell will maintain its normal shape and function, and the solution will not have any adverse effects on the cell.