Cell Membrane Transport
fatalbert619
bk-1_cell_membrane-transport_rptv_fix_fall_2013.rtfLab Report Name: ____________________
Section: ___________________
1
Cell Membrane Transport
Exercise 1 - Diffusion through an Artificial Membrane
Data Table 1- Changes during Dialysis
Color
Before Dialysis
After Dialysis
Solution in Plastic Cup
Solution in Dialysis Bag
Data Table 2- Benedict’s test Results
Color of Solution
Before Heating
After Heating
IKI solution in 16 oz cup
Solution in Dialysis Bag
Distilled water
Questions:
- What is the purpose of this exercise? What is being tested?
- What color change was observed in the dialysis tubing? What does that change indicate?
- Was there a color change in the water surrounding the tubing? If so, explain.
- What color change was observed in the water from the 16 oz cup containing the IKI used after heating? What does that change indicate?
- What does the Benedict’s reagent detect?
- What does the IKI solution detect?
- In what way is a cell membrane similar to the model cell made of dialysis tubing?
- Is the transport mechanism in the model cell passive or active, and why?
Exercise 2 –
Data Table 3: Diffusion of KMnO 4 at Various Temperatures
Questions:
- How does temperature affect the rate of diffusion?
- State a general hypothesis to cover how temperature affects rate of diffusion.
Exercise 3 - Tonicity and Diffusion:
Data Table 4-Potato Dimensions
Potato
Before Osmosis
(L x W)cm
After Osmosis
(L x W) cm
Tonicity: Hypertonic, Isotonic or Hypotonic
Distilled water
10% Sodium Chloride
Questions:
- What is the condition of each potato strip after soaking in the test tubes for an hour? Which one is limp and which one is crisp?
- How would you explain the difference in the conditions of the potato strips using the concept of tonicity?
- What was the tonicity of the fresh water solution with respect to the potato cells?
- What was the tonicity of the salt water solution with respect to the potato cells?
- How do the changes in the conditions of the potato strips relate to the wilting of plants?
- How does keeping vegetables cool slow them from wilting?
