1. Diffusion in Cells: Is bigger always better?
Lab #8

2. In diffusion, molecules move:
a) from low to high concentration
b) from high to low concentration
c) from an area where there are few to an area where there are many

3. 2) Molecules will move until they are:
a) all together in one place
b) on one side of a membrane
c) evenly distributed

4. 3) Diffusion occurs in:
a) Liquid
b) Gas
c) Both liquid and gas

5. Diffusion in Agar Cells
Simulation of diffusion into a cell
Agar “cell” put into solution
Indicator in cell will show diffusion of solution into cell (changes color)
Size of cell determines how long it takes for diffusion to complete
Hypothesis: Diffusion will complete fastest in __________ cube
3 cm
2 cm
1 cm

6. Diffusion in Agar Cells
Each pair will get a 5x3 cm “cube”
Use plastic knife to make a 3x3, 2x2 and 1x1 cm cube
Be as precise as possible!
3 cm
5 cm
2 cm
1 cm
Put all three cubes in beaker of solution for a total of 10 minutes

7. During the 10 minute wait for diffusion, copy data table below
After 10 minutes cut cube in half and fill in data table
Length of white area
Side x Side
Side x Side x Side
Diffusion depth / 10 minutes
Surface area / volume
(cm)
(cm/min)

8. When the size of a cell increases, does surface area or volume increase faster?
Which cube had more surface area in comparison to its volume?
Why do cells need to be so small?
Why is the endoplasmic
reticulum long, skinny
and folded?