Cell Membrane Transport

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Lab 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?