[Campbell Biology P.182] Based on Figure 7.12 and its accompanying description about osmosis... | Practice Question

Based on Figure 7.12 and its accompanying description about osmosis, what is the primary net movement of molecules across the selectively permeable membrane?

  • A: Both sugar and water molecules move freely across the membrane until concentrations are equal on both sides.
  • B: Sugar molecules move from the higher concentration side to the lower concentration side to achieve equilibrium.
  • C: Water molecules move from the side with a lower solute concentration (higher free water) to the side with a higher solute concentration (lower free water).
  • D: Water molecules move from the side with higher solute concentration to the side with lower solute concentration to dilute it.

Explanation

Figure 7.12 and its description clearly illustrate that the membrane is permeable to water but not to sugar. Water diffuses from an area of higher free water concentration which corresponds to lower solute concentration to an area of lower free water concentration higher solute concentration in an attempt to equalize the solute concentrations.