Part 1: What factors limit cell size? 1. What is surface area?
Surface area is the sum of the areas of all the faces of a figure.

2. What is volume?
Volume is the amount of space inside of the figure.

3. What cellular function is negatively impacted by an increase in cell size?
Getting rid of waste

4. What happens if a cell gets too large?
When a cell gets too large it becomes too big for material to cross fast enough, which can result in the cell dying.

5. Name two ways in which a large cell can minimize the negative effects of its size.
They can split into many smaller cells or change their shape to provide more surface area.

Part 2: Surface Area and Volume

In this section, you will compare the surface areas and volumes of three different cubes. Each cube represents a different cell.
6. Use the sliders to change the cell dimensions to those listed in Table 1. Complete Table 1 by recording the following data for each cell:

o Indicate the area of one surface (Column 2).
o Record the surface area and volume (Columns 3 & 4).
o Calculate and record the ratio of surface area to volume (Column 5).
o Determine and record the distance from the center of the cell to the closest face (Column 6).

7. As cells get larger, does the surface area-to-volume (SA/V) ratio get larger, smaller, or remain the same?

8. How does the change in the SA/V ratio compare with the change in distance from the center of the cell to the nearest face?

Part 3: How can a cell change its SA/V ratio without changing its overall volume?

Refer to Table 2. Imagine that Row 1 contains data for a large cell, Row 2 contains data for that same cell, after dividing, and Row 3 contains data for that same cell, after it changes shape. These changes are pictured below:

Return to Site 3 and use the sliders to change the cell dimensions to those listed in Table 2.
9. Complete Table 2, just as you did Table 1.

10. Would the total volume occupied by the cell(s) change when the first cell divides (several times) to form eight cells? Explain.

11. Did the surface area change when the cell divided several times to form eight cells? Explain. Describe how this change might affect each cell's ability to function efficiently in its environment.

12. Did the volume change when the cell became longer and thinner? Explain.

13. Did the surface area change when the cell became longer and thinner? Explain. How might this adaptation help the cell to continue growth?

14. For each of the three cells, compare the changes in the SA/V ratios to the changes in the distances from the cell's center to nearest face. Do the two quantities change similarly? Explain.

Part 4: What is the best size for a cell? (Homework)

Make sure you read the information at Site 4 before leaving class.
Address the Focus Question: Why are cells so small? Discuss two reasons, using the results of your research and experimentation.