To model the net movement of water into a cell using a semi-permeable bag that allows water to pass through but not salt, you would want to create a situation where the concentration of salt is higher outside the bag than inside. This creates a scenario that mimics a hypertonic environment outside the cell, which typically leads to water moving into the area with a lower concentration of solute (higher concentration of water) to achieve equilibrium.
Among the options provided, the best setup would be:
Place a bag containing a 30% salt solution into a beaker containing a 10% salt solution.
In this scenario:
- The bag has a higher concentration of salt (30%) than the solution in the beaker (10%).
- Water would move from the beaker (lower salt concentration, or higher water concentration) into the bag (higher salt concentration) in an attempt to equalize the concentrations of solute.
This setup effectively models the net movement of water into a cell when the outside environment is hypotonic relative to the inside of the bag (analogous to the inside of the cell).