You put a solution of sucrose into a bag of dialysis tubing, which is permeable to water but not to sucrose. You then put this bag into a beaker of water. An hour later, you observe that the bag has swelled due to

Question

A.  the high osmolarity of the surrounding water.
B.  passive transport of sucrose molecules.
C.  the osmotic pressure of the sucrose solution.
D.  the pressure exerted on the bag by the surrounding water.
E.  active transport of water molecules.

Clarify Question
What is the key concept addressed by the question?
What type of thinking is required?
 
Gather Content
What do you already know about the movement of water? What other information is related to the question?

Choose Answer
Given what you now know, what information is most likely to produce the correct answer?
 
Reflect on Process
Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?


Answer 1

C.  the osmotic pressure of the sucrose solution.

Clarify Question
What is the key concept addressed by the question?
        · This question is asking about the movement of water in an experimental setting.
What type of thinking is required?
        · Apply level:
            o You are being asked to take what you already know and use, or apply, it to the cause of the uptake of water by a model cell.
 
Gather Content
What do you already know about the movement of water? What other information is related to the question?
        · Solvents such as water move from high solvent concentration to low concentration solvent concentration via osmosis.
        · Concentration differences between two regions, often across a membrane, are driven by solute concentrations.
        · As solute concentration increases, osmotic pressure increases, and water concentration decreases.
        · Solutions move from areas of low osmotic pressure to areas of high osmotic pressure via osmosis.

Choose Answer
Given what you now know, what information is most likely to produce the correct answer?
        · The dialysis tubing is impermeable to sucrose, so those molecules cannot diffuse through the membrane.
        · If active transport was involved, the water would move in the opposite direction than it would via osmosis, that is, from low water concentration to high water concentration. This would shrink, rather than fill the dialysis tubing.
        · The surrounding water does not have high osmolarity, as no solute is mentioned.
        · The osmotic pressure of the sucrose solution would cause the water to move into the dialysis tubing until that osmotic pressure reaches equilibrium with the surrounding solution.
 
Reflect on Process
Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        · Apply level:
            o Answering this question correctly depended on your ability to use the movement of water in a new situation. If you got an incorrect answer, did you remember that osmosis is the movement of water from high water concentration to low water concentration, or that solute lowers water concentration in a solution? Did you have trouble extending the movement of water to determine the correct answer?