AP BIOLOGY

Detailed explanation-1: -If a cell is placed in an isotonic solution, there will be no net flow of water into or out of the cell, and the cell’s volume will remain stable. If the solute concentration outside the cell is the same as inside the cell, and the solutes cannot cross the membrane, then that solution is isotonic to the cell.

Detailed explanation-2: -An isotonic solution has the same solute concentration compared to the intracellular solute concentration. When a red blood cell is placed in an isotonic solution, there will be no net movement of water.

Detailed explanation-3: -When a cell is at osmotic equilibrium, the concentration of solutes inside and outside of the cell are equal, and they remain equal over time. This does not mean that solutes cannot enter or exit the cell.

Detailed explanation-4: -If the concentration gradient between two solutions is effectively zero, they are said to be isotonic.