Diffusion and Osmosis Ap Bio

Topics: Osmosis, Diffusion, Concentration Pages: 5 (1371 words) Published: December 5, 2012
4A- The hypothesis was partially supported because glucose left the bag and is proven by the positive test on the surrounding water. Also the beaker turned orange because of osmosis which attests to glucose leaving the bag. Iodine Potassium Iodine and water entered the bag. This was proven by the color change in the starch test as the bag turned black also because of osmosis. The only thing that the hypothesis lacked was that starch did not move at all. The beaker stayed yellow before and after because the bag is not permeable to starch. 4B- The hypothesis was supported because the diffusion rate was faster shown from the agar blocks. The materials passed through the membrane easily and quickly in the small cells than the large, making them more efficient. The smaller the cell is, the faster it can transport signals. The bigger cell took longer because it took up more surface area than the smaller cell. 4C- The hypothesis was supported because the yellow bag which had the largest amount of sucrose solution gained more mass than the others. Therefore it had the greatest molarity as more molarity means more percent of change in the mass. The yellow was a hypertonic solution, causing it to gain more mass and molarity. 4D- The hypothesis was supported because having no net movement meant that the sucrose solution 0 M would be isotonic in the slice of potatoes. The line from the graph that crosses the x-axis represents the molar concentration of sucrose with water potential that is equal to the potato tissue water potential. In this concentration there was no net gain or loss of water from the tissues. 4F- The hypothesis was supported because when the onion cell was placed in 15% NaCl, it went through plasmolysis and the cells because to shrink and the purple coloring have wider distance from each cell walls. However, as the onion cell was placed in freshwater the water moved in reached equilibrium, balancing everything and returning the cell back to its original state.

Lab 4A:
What entered the bag?| Where’s the proof?| Why did this happen?| Water| | |
IKI| | |
| | |
What Left the bag?| Where’s the proof?| Why did this happen?| Glucose| | |
| | |
| | |
What did not move?| Where’s the proof?| Why did this happen?| starch| | |

2) Based on your observations, rank the following by relative size, beginning with the smallest: glucose, water, IKI, membrane pores, starch molecules.

The smallest to largest is: IKI molecule, water molecule, membrane pores, glucose, and then starch.

3) What results would you expect if the experiment started with a Glucose/IKI solution inside the bag and only starch and water outside? Why?

The dialysis tubing would not diffuse but the water would because the molecule is too for it to fit in the membrane of the dialysis tube. The IKI would diffuse out but not the glucose. This is because it is too big to fit. The tubing will be brown because of the iodine and the beaker will not be clear but foggy because of the starch. The beaker will turn blue as IKI diffuses out and reacts with starch, however, the tubing will remain brown because starch does not move and cannot pass.

Lab 4B:
1) • Which solution is an acid?
The solution that was an acid was HCl.
2) • Which solution is a base?
The solution that was a base was NaOH.
3) • What color is the dye in the base? In the acid?
The color of the dye in the base, NaOH, was foggy while the acid, HCl, was clear. 4) • What color is the dye when mixed with the base?
The color of the dye when mixing with the base was pinkish/purple. 5) • What does the rate of diffusion mean for cell size? Diffusion occurs through the cell surface area. As the cell size increases there is a decrease in the ratio of the surface area to the volume. When the cell size decreases there is an increase in the ratio of the surface area to the volume. Greater volume means greater metabolic...
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