Question

water is moving across a membrane from solution a into solution b. what can be inferred?
solution a must have a higher solute concentration than solution b.
solution a and solution b must have the same concentration of solutes.
solution a must be pure water.
solution a must have a lower solute concentration than solution b.
solution b must be pure water.

Explanation:

Water moves across a membrane via osmosis from an area of lower solute concentration (higher water potential) to higher solute concentration (lower water potential). Since water moves from A to B, A has lower solute concentration than B. Other options are incorrect: equal concentrations would mean no net movement, pure water isn’t required for A, and B can’t be pure water if water moves into it.

Answer:

Solution A must have a lower solute concentration than Solution B.