Osmosis is a form of passive transport. Which of the following best defines osmosis?

• A. The movement of ions across a membrane using energy from ATP.
• B. The movement of water molecules across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration.
• C. The movement of solute molecules across a semipermeable membrane from an area of higher concentration to an area of lower concentration.
• D. The movement of water molecules across a semipermeable membrane from an area of higher solute concentration to an area of lower solute concentration.

Answer: (B)

Verified step by step guidance

1. Understand that osmosis is a specific type of passive transport involving the movement of water molecules.
2. Recall that passive transport means movement without the use of cellular energy (ATP).
3. Identify that osmosis occurs across a semipermeable membrane, which allows only certain molecules (like water) to pass through.
4. Recognize that water moves from an area of lower solute concentration (more water) to an area of higher solute concentration (less water) to balance solute concentrations on both sides.
5. Conclude that the best definition of osmosis is the movement of water molecules across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration.