Lab 4 Diffusion and Osmosis BIO201L
Glucose
Test n/a n/a Greenish No change
Strip
Table 4: Diffusion of Starch and Glucose Over Time
Indicator Dialysis Bag After 1 Hour Beaker Water After 1 Hour
IKI Solution changed to blue/black in color iodine passed- changed to yellow
Glucose Test Strip pale brownish brown
Post-Lab Questions
”1. Why is it necessary to have positive and negative controls in this experiment? ”
It is important to show that the indicator reagent and the starch and glucose used are
not faulty.
”2. Which substance(s) crossed the dialysis membrane? Support your response with
data-based evidence. ”
Dialysis tubing is a absorptive membrane, the water can pass through it, but not salt.
”3. Which molecules remained inside of the dialysis bag?
Blood cells and larger molecule proteins.
”4. Did all of the molecules diffuse out of the bag into the beaker? Why or why not? ”
Starch didn’t diffuse out . Starch molecules are to big to fit through the absorptive
membrane. Most of glucose dispersed out of the bag.
Experiment 3: Osmosis - Direction and Concentration Gradients
”Hypothesis: If we have two solutions with one being a higher concentration of
solvent that the other, the osmosis would go from the higher solvent to the lower
solvent.
Table 6: Sucrose Concentration vs. Tubing Permeability
Band Initial Volume Net Displacement
Sucrose % Final Volume (mL)
Color (mL) (mL)
Yello
30 10 16 6
w
Red 15 10 13 3
This study source was downloaded by 100000836551366 from CourseHero.com on 03-03-2022 07:03:10 GMT -06:00
https://www.coursehero.com/file/38660268/Lab4-dragged-2pdf/
Glucose
Test n/a n/a Greenish No change
Strip
Table 4: Diffusion of Starch and Glucose Over Time
Indicator Dialysis Bag After 1 Hour Beaker Water After 1 Hour
IKI Solution changed to blue/black in color iodine passed- changed to yellow
Glucose Test Strip pale brownish brown
Post-Lab Questions
”1. Why is it necessary to have positive and negative controls in this experiment? ”
It is important to show that the indicator reagent and the starch and glucose used are
not faulty.
”2. Which substance(s) crossed the dialysis membrane? Support your response with
data-based evidence. ”
Dialysis tubing is a absorptive membrane, the water can pass through it, but not salt.
”3. Which molecules remained inside of the dialysis bag?
Blood cells and larger molecule proteins.
”4. Did all of the molecules diffuse out of the bag into the beaker? Why or why not? ”
Starch didn’t diffuse out . Starch molecules are to big to fit through the absorptive
membrane. Most of glucose dispersed out of the bag.
Experiment 3: Osmosis - Direction and Concentration Gradients
”Hypothesis: If we have two solutions with one being a higher concentration of
solvent that the other, the osmosis would go from the higher solvent to the lower
solvent.
Table 6: Sucrose Concentration vs. Tubing Permeability
Band Initial Volume Net Displacement
Sucrose % Final Volume (mL)
Color (mL) (mL)
Yello
30 10 16 6
w
Red 15 10 13 3
This study source was downloaded by 100000836551366 from CourseHero.com on 03-03-2022 07:03:10 GMT -06:00
https://www.coursehero.com/file/38660268/Lab4-dragged-2pdf/
