Question

Dialysis bags can be used as models of cells to explore the movement of materials into and out of cells. Students set up an investigation with a dialysis bag containing a 2% iodine solution in a beaker containing a 9% starch solution as shown in the figure. Starch turns blue-black in the presence of iodine. The dialysis bag is permeable to water and iodine but not to starch.



Which two observations most accurately predict what will occur in the investigation?

(4 points)
Responses

The solution in the dialysis bag will turn blue-black.
The solution in the dialysis bag will turn blue-black.

The mass of the dialysis bag will decrease.
The mass of the dialysis bag will decrease.

The concentration of starch in the dialysis bag will increase.
The concentration of starch in the dialysis bag will increase.

The solution in the beaker will turn blue-black.
The solution in the beaker will turn blue-black.

The mass of the dialysis bag will increase.

Answer 1

Correct predictions:
- The solution in the beaker will turn blue-black. (Iodine diffuses out of the bag into the beaker and reacts with starch.)
- The mass of the dialysis bag will decrease. (The beaker solution is hypertonic (9% starch) relative to the bag (2% iodine), so water moves out of the bag by osmosis.)