Cube
Surface Area
(cm^2)
Volume
(cm^3)
SA to V ratio Diffusion
depth (mm)
Diffusion
rate (mm/
min)
1cm
6
1
6:1
5
0.5/1
2cm
24
8
3:1
5
0.5/1
3cm
54
27
2:1
5
0.5/1
1. Draw a measured sketch of the cross section of each cube after soaking in HCL.
3cm
3cm
0.5cm
*The sketch is attached at the end of lab.
2. What evidence is there that HCL diffuses into the cubes?
• The pink jelly gradually turns white from the outside to inside as time passes when
placed in HCL solution.
3. What happens to the diffusion rate as a cell gets larger?
• The diffusion rate stays the same no matter cell grows or not. The rate is 0.5 mm/min
and it’s same for all 1 cm, 2 cm, and 3 cm jellies.
4. What happens to the surface area-to-volume ratio as a cell gets larger?
• The surface area-to-volume ratio decreases as cell gets larger. It was 6:1 when the jelly
size was 1 cm, but it decreases to 3:1 when the size was 2 cm. Finally the ratio when
down to 2:1 when the jelly size was 3 cm.
5. Propose a hypothesis to explain why larger organisms have developed from more cells
rather than larger cells.
• If the cells get larger, then it would be hard for materials to go across the cell. On the
other hand, if the cells stay small, then the materials would easily move around the cells
and thus function properly. Therefore, for better functioning, larger organisms have
developed from more cells rather than larger cells.