Question

1. a diffusion investigation was conducted using iodine, starch and plastic bags to represent cells with semi - permeable membranes. iodine is a known indicator of the presence of starch. starch, normally white in color, will turn purple when in the presence of iodine. one teaspoon of starch was placed in the bag and dissolved with water. twenty drops of iodine were added to a beaker of water. the bag of starch was tied with a rubber band and placed in the beaker of iodine solution. after thirty minutes the students observed the changes in the solutions. the table below shows the results of the investigation. based on this experiment, which of the following should be inferred based on the results in the data table? data table: solution in the beaker - starting color: orange, color after 30 minutes: orange; solution in the bag - starting color: white, color after 30 minutes: purple neither iodine nor starch can move across a semi - permeable membrane. starch molecules can move across a semi - permeable membrane. iodine molecules can move across a semi - permeable membrane.

Explanation:

Iodine is an indicator for starch, turning it purple. The solution in the beaker (with iodine initially) remained orange and the solution in the bag (with starch initially) turned purple. This indicates that iodine molecules diffused across the semi - permeable membrane into the bag to react with starch, but starch molecules did not move out as the beaker solution did not change color to purple.

Answer:

lodine molecules can move across a semipermeable membrane.