B. A student investigated the diffusion of substances using a Visking tubing, an artificial membrane which has some of the properties of cell membranes as
shown below.
elastic
band
top of syringe
test tube
starch solution
Bag filled with starch
solution and placed into
a test-tube of water
water
Visking
bag
knot
The student added some iodine solution to the water in the test tube.
After 30 minutes at room temperature, the contents of the Visking bag were
stained blue-black, but the water outside remained a yellow colour.
i. Explain the results.