As you complete the lab, answer the questions below, when completed save with your name and then attach to the Lab 6 drop box.
Experiment 1: Diffusion through a liquid
1. A concentration gradient affects the direction that solutes diffusion. Describe how a molecules move with respect to the concentration.
2. How does the size of a solute affect the rate of diffusion? Consider the size and shape of a molecule in your response.
3. Does polarity affect the rate of diffusion? Explain your answer using scientific principles.
4. After completing experiment 1, fill out the tables below and answer the questions following:
Table 1: Diffusion Through Liquids
Corn Syrup in mm
Time (sec) Blue Dye
mm Red Dye
mm
10
20
30
40
50
60
70
80
90
100
110
120
Table 2: Diffusion Rate of Dyes in Corn Syrup
Dye Name Molecular Weight Total Distance Traveled (mm) Speed of Diffusion (mm/hr)*
Blue Dye
Red Dye
1. Record your hypothesis from Step 3 here. Be sure to validate your predictions with scientific reasoning.
2. Which dye diffused the fastest?
3. Does the rate of diffusion correspond with the molecular weight of the dye?
4. Does the rate of diffusion change over time? Why or why not?
5. Make your own line graph using your data and insert as .jpg in your report here.
6. Explain the role diffusion plays in this process of getting oxygen to your cells of the human body.
Experiment 2: Concentration gradients and membrane permeability
Table 3: Indicator Reagent Data
Starch + Conrol (color) Starch Negative Control (color) Glucose +
Control (color) Glucose Negative
Control (color)
IKI Solution N/A N/A
Glucose Test Strip N/A N/A
Table 4: Glucose Diffusion
Dialysis Bag after 60 minutes Beaker water after 60 minutes
IKI Solution
Glucose Test Strip
Experiment 2:
Do experiment on Lab 6, Diffusion
Questions
1. Why is it necessary to have positive and negative controls in this experiment?
2. Include a picture of you and your experimental set-up here:
3. Which substance crossed the dialysis membrane? What evidence from your results proves this?
4. What molecules remained inside of the dialysis bag?
5. Of the substances that diffused through the bag, did all of the molecules diffuse out? Explain.
6. Is the bag hypotonic with regards to the IKI solution, or the beaker? What about the starch solution?
7. What results would you expect if the experiment started with glucose and Lugol's Solution inside of the bag, and starch and water in the beaker? Why?
8. Draw a diagram of this set up. Use arrows to depict the movement of each substance in the dialysis bag and the beaker.
9. What type of membrane does the dialysis tubing represent? Give an example of this type of membrane that can be found inside the body.
10. How does the glucose concentration affect diffusion rate?