Surface Area to Volume Laboratory

The cell needs to obtain nutrients and oxygen through the cell membrane and expel wastes. The closer the organelles are to the cell membrane the more efficient that the transfer can occur.

1. Purpose: determine the Surface area to volume ratio of a four different cells.

2.Determine the theoretical volume of a cube cell and the actual volume a cube cell.

3.Determine the theoretical surface area of a cube cell and the actual surface area a cube cell.

4.Determine ratio of surface area to volume of a theoretical cell and actual cell.

5.Graph the data of the actual and the theoretical ratio

6.Calculate the percent error

Materials Formulas

PaperSurface area S= L x W X 6

Cm ruler

ScissorsVolume V = L xW x H

Graduated cylinders

Graph paperSurface area/Volume ratio = S/V

Tape

Sand% error = (actual - theoretical) x 100

theoretical

Method

Construct 4 cube boxes, 1cm sides, 2 cm sides, 3 cm sides and 4 cm sides. Use the template below.

Fill each box with sand and level off the top. Carefully dump the sand into the appropriate size graduated cylinder to find the actual volume. (Work over the plastic tray when adding sand to the box or measuring sand volumes in the graduated cyliner)

Calculate the Theoretical data and write all appropriate data in the chart below.

Cell Size / Actual surface area
S / Actual volume
V / Actual Ratio of
S/V / Theoretical surface area
S / Theoretical volume
V / Theoretical Ratio of
S/V / % error
actual ratio to theoretical ratio
1
2
3
4

Construct a graph of the Ratio of S/V. Make the Actual Ratio a Blue line and make the Theoretical Ratio a Red line. The Cell Size is the X axis and the Ratio is the Y axis.(Hint: use the ENTIRE graph, the bigger the graph the better)

As the cell size gets bigger, what happens to the:

Surface area?______

Volume?______

Ratio?______

What would account for differences between the actual ratio and the theoretical ratio?

Which cell size has the smallest % error?

Read the appropriate section in your text. Write a paragraph describing the value of the surface area to volume ratio to the living cell. Why don’t big organisms have larger cells than small organisms but have more cells than small organisms?


Name______per______date______