1. What Is The Connection?

12. A conceptual problem… Q = How do cells feed and excrete? A = Via their cell membranes So therefore, shouldn’t cells require MORE surface area?

14. Lab: Assessing the Rate of Cellular Diffusion v. Differing Surface Area to Volume Ratios Purpose: To determine how the size of a cell is related to its ability to perform diffusion Method: Measurement of conductivity of the solution. The greater the rate of diffusion, the greater the rate of change in conductivity (as measured in µS/cm/sec)

15. Calculating S.A.: Vol Ratios From block of sodium- infused agar, cut 3 2x2x2 blocks Cut 2 nd block into eight cubes Cut 3 rd block into 64 cubes Calculate cumulative S.A.: Vol. ratios for each set of cubes

16. Collecting the data Place the first 2 cm 3 cube into 300 mL of tap water Immerse the conductivity probe into the tap water bath Collect data, while STIRRING CONSTANTLY for 300 seconds Determine the slope in µS/cm/sec

17. Processing/Interpreting The Data Graph the rate (y- axis) vs. ratio of S.A.: Vol. (x-axis) Answer the analysis questions in your lab notebook