Dialysis bags or model âcellsâ (A, B, C and D) are placed in beakers containing a 20% sucrose solution. Each model âcellâ contains an unknown concentration of sucrose solution. Every 15 minutes, the model âcellsâ are weighed and the data entered in the table below. Table: Mass of Model âCellsâ Containing Different Concentrations of Sucrose Time (minutes) is 0,15,30,45. âCellâ containing solution A is 11.4, 11.3, 11.2,11.3(mass grams) âCellâ containing solution B is 12.5, 13, 13.5, 14(mass grams) âCellâ containing solution C is 10.8,9.6, 8.2, 7.2(mass grams) âCellâ containing solution D is 10.8, 10.2, 9.5, 9.2(mass grams) what is the Movement of Water, % Sucrose in âCellâ & Tonicity in âCellâ of each cell (A-D)
a) Use the data in the table to determine the movement of water. Choose from âInto the cellâ, âOut of the cellâ or âNo net movement of waterâ Write your answer in the row of the table labeled âMovement of Waterâ.
b) Based on the movement of water, you can determine what the concentration each solution must have been at the beginning of the experiment for each model âcellâ A-D. Choose from 40%, 20%, 15% or 10%. Write your answer in the row of the table labeled â% Sucrose in Cellâ.
c) Determine whether each sucrose solution in the âcellâ is âhypertonicâ, âisotonicâ or âhypotonicâ relative to the solution outside the âcellâ. Write your answer in the row of the table labeled âTonicity in Cellâ. Answer the questions below about Part II of this exercise:
1) A. Explain why was there little or no weight change for the model âcellâ containing solution A?
B. This system is said to be at equilibrium. Explain what equilibrium means in terms of the movement of water across the plasma membrane of a cell?
2) The model âcellâ containing solution B gained weight. Therefore, the water moved _________ the âcellâ. Explain why the water moved as it did in this model system.
3) Model âcellsâ C and D both lost weight. Therefore, the water moved _________ the âcellâ. Explain why the water moved as it did in these systems.
4) A. âCellâ C lost more weight than âcellâ D over the same amount of time (60 min). Therefore, âcellâ C lost water at a slower or faster rate than âcellâ D. (circle one)
B. Explain the cause of the difference in the rate of water loss for âcellâ C and D.
5) Do you see a pattern of how water flows into or out of the cell based on the concentration of solute?
Water always moves from a ______________tonic solution to a ____________tonic solution.
6) In the experiment your group will design, you will be using a piece of potato composed of many living cells. Based upon what you have learned about osmosis and tonicity, predict whether a potato core would gain weight, lose weight or stay about the same weight if you placed it in each of the following solutions: Hypertonic â Isotonic - Hypotonic â
