*INTRODUCTION:*

Cells are limited in how large they can
be. This is because the surface area and volume ratio does not stay the same as
their size increases. Because of this, it is harder for a large cell to pass
materials in and out of the membrane, and to move materials through the cell.

In this lab, you will make cube shaped models to represent cells. The dimension
along one side will be doubled with each model. You will then calculate the
surface area, volume, and the ratio between the two.

**MATERIALS:**

Scissors

Construction paper

Tape

Metric ruler

**PROCEDURE:**

1. Construct three cell models like the
pattern shown. The dimensions of a side will double each time, with the sides
being **2 cm**, **4 cm**, and **8 cm**. Fold and tape into cubes with
the tabs to the inside. Record the dimensions in the **DATA TABLE** (the
first one is done for you in the table).

DATA
TABLE: Cell Size Comparison |
||||

Cell |
Dimensions (cm) |
Surface Area (cm ^{2}) |
Volume (cm ^{3}) |
Ratio Surface area to Volume |
---|---|---|---|---|

1 |
2 X 2 X 2 |
|||

2 |
||||

3 |

*CALCULATIONS:*

2. Calculate the total surface area for each cell model by the following formula:

3. Calculate the volumes for each cell model by the following formula:

4. Calculate the surface area-to-volume ratio for each cell model by the following formula:

ratio = | surface areavolume |
---|

- These ratios show how many times
larger the surface area is as compared to the volume. Notice that it becomes
less than one very quickly.
**QUESTIONS:**1. Which model has the largest surface area?

2. Which model has the largest volume?

3. Which model has the largest ratio?

4. To maintain life, and carry-out cellular functions, materials must be able to move into and out of the cell. Also, material needs to be able to move within the cell. What might be the advantage of having a large surface area?

- 5. What might be the disadvantage of
having a large volume?