1. Rate of Diffusion Experimental Design

2. Rate of Diffusion Experimental Design
The cell membrane regulates what enters and leaves the cell and also provides protection and support.
What allows the cell to be “selective” in what enters and leaves? ___________________ 
The core of nearly all cell membranes is a double-layered sheet called a lipid bilayer.
Draw a portion of this lipid bilayer below and make sure to include all four components.

3. Factors Affecting Diffusion
Most materials entering the cell pass across this membrane through diffusion.
What are the five factors that affect the rate of diffusion? In the space next to each describe how they affect diffusion.
1. __________________________
2. __________________________
3. __________________________
4. __________________________
5. __________________________

4. Class Example
We will go through one as an example, but then you will be choosing another factor to manipulate and design a controlled experiment testing how this factor affects the rate of diffusion.

5. Class Example: Surface Area
Hypothesis: If The dialysis tubing has more surface area, then more diffusion will occur
Control Group: regular sized dialysis sac of solution
Experimental Group: Larger dialysis sac of solution
Independent Variable: size of the dialysis sac
Dependent Variable: amount of diffusion (how much weight it gained due to diffusion)
Procedure:
weigh sac
Put in beakers. Waith 30 minutes
Weigh sacs and determine difference in weight
Calculate diffusion

6. Your Example: (Choose one of the other factors and design)
Hypothesis: ___________________________________________
Control Group: _________________________________________
Experimental Group: _____________________________________
Independent Variable: ___________________________________
Dependent Variable: _____________________________________
Procedure:
OPTIONS: temperature, concentration difference, permeability, and particle size