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Cell Size Lab (potato)


What is the effect of cube size on the ability of the cell to interact with their external environments?


(Summarize what you know about the size of cells, surface area and volume, and the interaction of cells with their external environments.)


(Predict what will happen to the interaction of cells with their external environments when the size of the cubes are increased.)


Safety goggles Potato Metric ruler Spoon or tongs,
Iodine solution Knife Beaker, 100mL Distilled water ~60 mL


  1. Safety goggles will be worn at all times.
  2. Each group will cut three potato cubes: a 0.5cm cube, a 1cm cube, and a 2cm cube. Cut as accurately as possible.
  3. Place the cubes in the bottom of the beaker such that the potato cubes are not touching the sides of the beaker or each other.
  4. Pour in distilled water until the potato cubes are just covered. Add ___ drops of iodine solution.
  5. Every ___ minutes swirl the iodine solution gently. After ___ minutes, use a spoon or tongs to remove the blocks and blot dry with a paper towel.
  6. Pour the iodine solution into the waster container the instructor showed you.
  7. Promptly cut each block in half and measure the depth to which the brown color has penetrated.
  8. Sketch each block's cross section.


(Record all data on a data table. Include that data table and any calculations and graphs in this section)

Length of a cube side Surface area (cm2) Volume (cm3) Penetration distance (cm) Surface area / volume ratio


  1. Make two x-y scatter plot graphs:
    1. side length vs. the surface area AND side length vs. the volume .
    2. the volume vs. the surface area.
  2. For each cube make a calculation of the percentage of penetration.
    1. % penetration = volume of color change / total volume
    2. Volume of color change = Total volume – Not brown volume
    Length of a cube side (cm) Volume (cm3) Penetration distance (cm) Length of not brown cube side (cm) Not brown volume (cm3) % penetration
  3. Use a scatter plot to show S/V Ratio vs. percent of penetration.


(Write your conclusion in this section. Be sure to follow all guidelines for writing conclusions to experiments and include data and an explanation of how the data supports your conclusion)