In Full Color

Juniors and seniors in AP Biology experimented with cubes and colors to determine the importance of the surface area and volume of cells to the diffusion of particles through the cell membrane. After cutting agar prepared with an acid-base indicator into cubes of different sizes, the students placed the cubes into a basic solution and watched the cubes turn bright pink. After 30 minutes, they cut the cubes in half and measured the width of the area inside the cube that had not yet turned pink. In their analysis, they'll apply what they observed to answer questions about the ratio of surface area to volume in the function of human cells.