Osmolarity

Definition

Osmolarity is the measure of solute concentration per unit volume of solution, expressed as osmoles of solute per liter. It is crucial for understanding how water moves across cell membranes during passive transport.

5 Must Know Facts For Your Next Test

1. Osmolarity affects the direction and rate at which water moves across cell membranes through osmosis.
2. A solution with high osmolarity has a greater concentration of solutes compared to one with low osmolarity.
3. Cells maintain osmotic balance by regulating their internal osmolarity relative to their external environment.
4. Hyperosmotic solutions have higher osmolarity than the cell's cytoplasm, often causing cells to lose water and shrink.
5. Hypoosmotic solutions have lower osmolarity than the cell's cytoplasm, potentially causing cells to gain water and swell.

Review Questions

• How does a hyperosmotic solution affect a cell?
• What role does osmolarity play in passive transport?
• Explain the difference between hyperosmotic and hypoosmotic solutions.

Related terms

Osmosis:

The movement of water molecules from an area of lower solute concentration to an area of higher solute concentration through a semipermeable membrane.

Tonicity:

The ability of a surrounding solution to cause a cell to gain or lose water based on its osmolarity.

Isotonic Solution: A solution that has the same osmolarity as the cytoplasm of a cell, resulting in no net movement of water into or out of the cell.