lab 1 Essay

Submitted By Paulina-Trzonkowska
Words: 1127
Pages: 5

Paulina Trzonkowska
INTRODUCTION Diffusion is the random movement of molecules from an area of higher concentration of those molecules to an area of lower concentration. Osmosis is a special case of diffusion, the diffusion of water. In the lab setup there is a dialysis bag with different concentrations of sucrose and glucose. The dialysis bag is then placed in distilled water. Glucose and some iodine is leaving the bag. Sucrose is staying inside the dialysis bag because it will not be able to pass through it. The indicators that will be used to test glucose is Benedict’s solution or testape. The presence of starch will be tested with Lugol’s solution. The color changes that I observed was that the color of the solution in the beaker stayed the same as amber while the starch in the bag turned from white to purple. The glucose changed from blue to yellow-orange. PROBLEM
In the lab we were trying to solve what substances are entering the bag and leaving the bag.
After 20-30 minutes I expected that starch to remain because of its large size, iodine entering the bag and glucose leaving the bag.
a. -dialysis bag
-glucose,starch,iodine,H2O, Benedict’s solution
b. First you would need to obtain a dialysis bag and to tie one end of it with a string and open the other side. In the bag place 15mL of the 15% glucose/1% starch and tie off the other end of the bag leaving enough space for the bag to expand. Record data for any color changes. Later test the solution for the presence of glucose with the Benedict’s test. Fill a beaker with 2/3 full with H2O. In the H2O add 4mL of Lugol’s solution and record the color change as well. Test this for glucose and record results. Immerse the bag into the beaker of solution and allow it to stand for approximately 30 minutes or until u see a distinct color change in bag or beaker.Record the color changes. Lastly test the liquid in beaker and the bag for glucose and record results.


a. When doing the lab I observed that iodine and water is entering and glucose is leaving the bag. The color changes in the bag and the presence of glucose in the bag prove this. The bag turned from clear to purple and we could tell that there was starch in the bag. Even though there was no color change in the beaker and stayed the same color,amber,the explanation for this is how starch was not able to pass through the dialysis bag. Glucose, as the Benedict’s test proves, was able to move freely along with the water and IKI solution.
b.Yes the hypothesis was proven correct because the change of the color of the bag went from clear to purple showing diffusion.
c. 1. Glucose is leaving the bag and some iodine is entering the bag. The experimental evidence that supports my answer is seeing how iodine is reacting to starch and turns into a purple hue, showing iodine entering the bag and glucose leaving.
2. In the experimental results showed that glucose transported out of the bag due to its smaller size, while starch remained due to its larger size. The glucose transported into the water out of the bag because of the low glucose concentration in the beaker. It goes from high to low.
3. By measuring the weight of the bag and not putting any iodine is very hard.
4. Smallest to biggest: Glucose molecules, water molecules, IKI molecules, membrane pores, starch molecules.
5.Glucose would diffuse into the beaker as well as iodine and water will diffuse into the bag. Starch will not diffuse at all.

Plasmolysis is the contraction of the cytoplasm of a plant cell and response to diffusion of water out of the cell into a hypertonic solution. Turgor is the expansion of the cytoplasm of a plant cell and response to diffusion of water into the cell into a hypotonic solution. In a hypertonic solution there will be a plasmolysis and in a hypotonic solution there will be a turgor. In a plant when…