Osmosis is best defined as the movement of:

• A. gas molecules from a region of higher pressure to a region of lower pressure across any membrane
• B. solute particles from a region of higher concentration to a region of lower concentration across a semipermeable membrane
• C. water molecules from a region of lower solute concentration to a region of higher solute concentration across a semipermeable membrane
• D. water molecules from a region of higher solute concentration to a region of lower solute concentration across a semipermeable membrane

Answer: (C)

Verified step by step guidance

1. Understand that osmosis specifically refers to the movement of solvent molecules, typically water, rather than solute particles or gases.
2. Recognize that osmosis occurs across a semipermeable membrane, which allows only certain molecules (like water) to pass through while blocking solute particles.
3. Recall that water moves from a region of lower solute concentration (which means higher water concentration) to a region of higher solute concentration (which means lower water concentration) to balance solute concentrations on both sides.
4. Eliminate options that describe movement of gases or solutes, as these do not define osmosis.
5. Conclude that the correct definition of osmosis is the movement of water molecules from a region of lower solute concentration to a region of higher solute concentration across a semipermeable membrane.