Notes

1. What is a potato? It is a vegetable also known as a tuber made up of cells. +2

2. Why did the diffusion of iodine into the potato cube cause the color change from white to black? Cells of the potato absorbed the iodine through the cell membrane (diffusion). +2

3. If each cube represented a living cell, and the iodine solution was a substance needed within the cell, what problem might the largest cell have? The largest cell would have trouble getting nutrients to all parts of the cell fast enough to support its size. +2


4. Examine your data in table 2. What pattern do you notice in the relationship between cube size and the rate of diffusion? The rate of diffusion is constant. +2


5. Examine your data in table 1. Describe what happens to the surface area and the volume as the cell grows larger. As the cell grows larger the volume amount increases at a higher rate then the surface area thus as cells increase in size they lose the high ratio of surface area to volume. +2


6. Still considering table 1, what happens to the ratio between surface area and volume as the cell grows larger? The surface area and volume ratio start to show less of a difference in the amount of each total (12:1 -> 6:1 -> 3:1) . +2


7. According to your data, which cell was most successful at receiving the needed nutrient (iodine solution) in the allowed time? The smallest cell (.5 cm). +2

8. What can you say about the surface area to volume ratio that will best meet the needs of living cells? In order to get the nutrients needed for survival into all parts of the cell it is necessary for the cell to remain small with a high surface area to volume ratio. +2


9. Why is surface area significant in this situation? Surface area allows for contact space for nutrients to enter the cell, the higher the amount of surface area compared to amount of volume the more nutrients the cell can obtain and quickly distribute to the volume of the cell. +2

10. Use what you learned in this lab to answer the research question. Individual cells do not grow large because the cell would be unable to distribute the needed nutrients to the cells increasing volume. As the size increases the volume increases at a faster rate then the surface area thus slowing the cell ability to move nutrients into the interior of the cell were it is needed for survival. So the cell divides and stays small which creates many cells with high amounts of surface area per volume ratios. +2


11. Evaluate your initial hypothesis (as stated in the PreLab). Answer will very but this should discuss whether the hypothesis was supported or not by the data and which cell size is best. +2

12. Graph the Percent Volume of Cube Changed by cell size (0.5, 1 and 2cm), then use your graph to predict the percent Volume of Cube Changed for a hypothetical cube of .25 cm, and one of 4 cm.

It looks as if the 4 cm cell would have a negative amount of nutrients getting in but this is not possible but it certainly shows that the larger cell get much less then the smaller cell. The .25 trend seems to show that 104% of the cell will get nutrients which is also impossible but the entire cell could be getting nutrients (100%) much more efficient then the larger cell. +4



Trend line graph below.