Biology lab

Name
Professor
Course
Date
Semi-Permeable Membrane
Hypothesis
If the selectively permeable membrane is permeable to starch, then starch molecules will be found in the bag, starch molecules will be found in the water outside the bag, and water will move into the bag
If the selectively permeable membrane is permeable to Lugol’s iodine but impermeable to glucose, then glucose and iodine will be found in the bag, iodine will be found in the water outside the bag and water will move into the bag.
If the selectively permeable membrane is permeable to glucose but impermeable to starch then glucose and starch will be found in the bag, glucose will be found in the water outside the bag and water will move out of the bag.
Materials
Ten mL graduated cylinder
400 ml beakers
Lugol’s iodine
2 Dropper bottle
Benedict reagent
Test tube holder
Hotplate
Scissors
String
Weigh boat
Triple beam balance
Method
The experiment used a dialysis tubing as the semi-permeable membrane. It was pre-soaked in deionized water and carefully into smaller sections. One end was folded and tied firmly with a string. The other end was held open and 10 ml of glucose and 10 ml of starch-filled in. The open end was tied up and checked for leaks. The tie was a long thread that would be used later to hold the dialysis tubing on the beaker. The tubing was rolled back and forth to mix the content thoroughly. It was then weighed on the weigh boat and the triple beam balance and the weight and color recorded.
In an empty and clean 400 ml beaker, 200 ml of water was added and several drops of Lugol’s iodine (I2KI) solution, until the water turned yellow.

The tubing was left in the beaker for 30 minutes with the strings hanging on the side. After 30 minutes it was removed and placed in another 400 ml beaker. It was weighed again, and their weight and color noted down.
50 ml of water in a beaker was placed on a hot plate. Three test tubes were labeled Control, Beaker, and Bag using a China marker and placed in the beaker on the hot plate. Two pipettes of deionized water were placed in the control test tubes. Scissors were used to cut one end of the dialysis tubing and two pipettes of solution from the dialysis tubing’s transferred to the test tube called bag. Two pipettes of the solution in the original beaker were placed in the tube labeled beaker. A drop of Benedict’s reagent was dropped into each test tube. The water in the beaker was heated for three minutes. The hot plate was turned off and the test tubes were transferred to the test tube holders. The observation was recorded.
Questions
The selective membrane was permeable to iodine and glucose. It led to a color change in the contents of the dialysis tubing and in the beaker. Iodine moved into the dialysis tubing leading to a change in color from colorless to blue-black. Glucose and water moved from the tubing to the beaker making the content change to yellow amber (Fisher, Kathy and Jennifer, 332).
Iodine solution was used to test for the presence of starch. Hence the change in color in the tubing to blue-black.
Benedict’s test was used to test the presence of glucose in the two solutions.

Reference
Fisher, Kathleen, Kathy Williams and Jennifer Lineback. “Osmosis and Diffusion Conceptual Assessment.” Life Sciences Education (2017): 319 -413.