Question

Background: Cells are so small that their existence went unnoticed until the microscope was invented. The microscope allows scientists to examine the cellular makeup of living organisms for the first time. A question that arises is: why are cells so small? Is there a factor that limits the size of a cell? In this lab, you will investigate the possibility that diffusion of nutrients into the cell may be a limiting factor on cell size. In this lab, you will work with raw potatoes, cut into cubes to mimic a working model of a cell. You will cut the potatoes into cubes of p QQ1re-determined size and then place the cubes in a dish containing a food-coloring solution. When the food coloring diffuses into the potato, it will produce a visible stain. After incubating all potato cubes that are simulating cells in a food-coloring solution for the same time period, you will slice open each of them to determine how far the food coloring diffused. By comparing the distance that the food-coloring diffuses into each size of cell that you make, you will be able to draw conclusions about whether the rate of material transport may be one of the limiting factors on cell size. Question How does cell size affect the rate of diffusion of materials into a cell? Materials

Answer 1

When the cell increases in size, the volume increases faster than the surface area, because volume is cubed where surface area is squared. When there is more volume and less surface area, diffusion takes longer and is less effective.