A scientist performs an experiment in which they create an artificial cell with a selectively permeable membrane through which only water can pass. They inject a 5M solution of glucose into the cell and then place the cell into a beaker containing 10M glucose. What effect do you expect to observe?

Question

A.  Water moves out of the cell
B.  Glucose moves out of the cell
C.  No net change in cell weight
D.  Water moves into the cell
E.  Glucose moves into the cell

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?
· What key words does the question contain and what do they mean?

Gather Content
· What do you know about osmotic concentration? How does it relate to the question?

Consider Possibilities
· What other information is related to the question? Which information is most useful?

Choose Answer
· Given what you now know, what information and/or problem solving approach 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

A.  Water moves out of the cell

Clarify Question
· What is the key concept addressed by the question?
        o The question asks about osmotic concentration.
· What type of thinking is required?
        o You are being asked to apply your understanding of osmotic concentration to predict what will happen to a cell if it is injected with 5M glucose and then placed into a solution that is 10M glucose.
· What key words does the question contain and what do they mean?
        o Selectively permeable membrane – this is a membrane that keeps polar and charged molecules from crossing it, but will allow water and gasses to diffuse through the membrane.
        o 5M glucose – M is molar or moles per liter. A 5M solution of glucose is very high, for example soda is 0.5M glucose. Glucose is a polar molecule and will not be able to cross the membrane.

Gather Content
· What do you know about osmotic concentration? How does it relate to the question?
        o Increasing the amount of glucose in the synthetic cell to 5M will increase its osmotic concentration relative to water.
        o When the cell is placed into a 10M solution, the cell will have a lower osmotic concentration relative to the 10M solution.

Consider Possibilities
· What other information is related to the question? Which information is most useful?
        o With a decreased osmotic concentration of glucose inside of the cell, the cell will be hypoosmotic and the 10M solution hyper osmotic. Water moves from areas of lower osmotic concentration to higher osmotic concentration until the osmotic concentrations on both sides of the membrane are the same.

Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o Since the osmotic concentration on the inside of the cell (5M) is lower than the solution (10M), the water will move out of the cell by osmosis.

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?
        o This question asked you to apply your understanding of osmotic concentration to predict the direction water will move when a cell is made hypoosmotic to its surroundings. If you got the correct answer, great job! If you got an incorrect answer, where did the process break down? Did you understand what would happen to the osmotic concentration inside the cell when it was injected with 5M glucose? Did you recall that water will move from an area of lower to higher osmotic concentration? Did you recall that a semipermeable membrane will not allow polar molecules like glucose to cross while water can cross the membrane?