OPTIONS FOR INQUIRY

OPTIONS FOR INQUIRY

Modeling Cell Surface Area–to-Volume Ratio

A cell's surface area–to-volume ratio affects the amount of material that can diffuse across the membrane and throughout the cell. You will make cell models to determine how this ratio changes as cell size increases.

PROBLEM

Which cell has the greatest surface area–to-volume ratio?

[pic 1]  [pic 2]  [pic 3]

MATERIALS

∙        Ruler

∙        Modeling clay

PROCESS SKILLS

∙        Modeling

∙        Inferring

PROCEDURE

Part I

        1.        Make three model cells by using the clay to shape three cubes. Cell A should be 3 cm on each side, cell B should be 2 cm on each side, and cell C should be 1 cm on each side. Use the ruler to make exact measurements.

[pic 4]

        2.        Calculate the area of one side of each cell. Calculate the total surface area of each cell. Record your data in Table 1. Hint: Multiply the area of one side by the number of sides.

[pic 5]

        3.        Calculate the volume of each cell. Record your data in the table. Hint: Multiply the length by the width by the height of the cube.

[pic 6]

        4.        Calculate the ratio of surface area to volume for each cell. For example, for cell A, the ratio would be 54 cm2:27 cm3 = = 2:1 = 2. Record your data in table 1.

Part II

        5.        For this part, you will got to https://www.youtube.com/watch?v=o0ZxMGghK40 , watch the video starting at the 6th minute. Note that in the video, the dimensions of cell C are different from part I.

ANALYZE AND CONCLUDE

        1.        Analyze How does the surface area–to-volume ratio change as cell size increases? How might this affect the diffusion of materials throughout a cell        

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