Question

Describe the way the water would move through the semipermeable membrane. Explain what type of transport this is, how you know, and whether or not it requires energy. * Your answer

Answer 1

Water will move from A to B through the semipermeable membrane.

This type of water transport is called osmosis.

In osmosis when two solutions with different solute concentration is separated by a semipermeable membrane, water molecules move from lower concentration to higher concentration through the semipermeable membrane. In the picture 'A' arm of the tube contains a solution with higher concentration than arm 'B'. These two solutions are separated by a semipermeable membrane. As solute concentration of arm 'A' is higher, this solution will contain less free energy than the solution of 'B' arm. Water will move from solution with higher free energy to the solution with lower free energy through the semipermeable membrane. This movement of water molecules will continue until the concentrations of both solutions become equal. After equilibrium is reached, the water level of arm A will be higher than the initial state and the water level of arm 'B' will be lower than the initial state as water has moved from arm 'A' to arm 'B'.

The whole process is diagrammed in the picture below.

Semipermeable membrane Initial state Final state

This movement of water does not require energy.