Was the membrane-tubing-permeable to starch

Answer 1

I'm assuming this is in reference to an experiment where you put a starch in dialysis tubing, and then put iodine in surrounding solution.

Dialysis tubing has a limit of roughly mwco (molecular weight cut off of 10,000). Iodine has a molecular weight of roughly 126, so it can pass through. On the other hand, starch is a polymer of 1000's of glucose molecules. Glucose (C6H12O6) has a molecular weight of roughly 180. 1000 * 180 = 180,000, so glucose cannot pass through the dialysis tubing.

In this experiment you should see the sealed tubing turn purple-pinkish after the iodine diffuses through. The outside solution should remain the same color.

Answer 2

No, the membrane tubing was not permeable to starch, as starch molecules are too large to pass through the pores of the membrane. Only smaller molecules like glucose and water were able to pass through.