Advanced Placement (AP) Biology Practice Exam

In terms of solute concentration, what does the term hypertonic imply?

1. Equal solute and solvent concentration

2. More solute, less water

3. Less solute, more water

4. No effect on cell size

The correct answer is: More solute, less water

The term hypertonic refers to a solution that has a higher concentration of solute compared to another solution. In biological contexts, when a cell is placed in a hypertonic solution, it means that the solution outside the cell contains more solute and less water than the inside of the cell. This difference in solute concentration causes water to move out of the cell in an effort to balance the concentration on both sides of the cell membrane, leading to cell shrinkage or crenation. This is significant in processes like osmosis, where water moves from an area of lower solute concentration (more water) to an area of higher solute concentration (less water) to achieve equilibrium. Understanding the implications of hypertonicity is crucial in cellular biology, as it affects cell size, shape, and function.