Part A: Title: Diffusion Diffusion is the spontaneous movement of particles from where they are more concentrated to where they are less concentrated. For this experiment, a 14 cm glass was filled with cold tap water. A drop of red food coloring was dropped in the cup. A stopwatch was used to measure the time it took for the food coloring to get to the bottom of the cup. The average diffusion rate was . 78 cm a second. If a different color was used, I do not think it would have made a difference in the results. The mood of the person experimenting could possibly alter the results.
For example, if a person is under stress, they may accidentally squeeze too much altering the rate of diffusion. If the water was warmer, this may have sped the diffusion process because the molecules would have been moving faster. If the water was freezing, this may have slowed the diffusion process because the molecules may have been moving slower. Part B: Title: The effect of salt concentration on osmosis in potato. Introduction: 1. The purpose of doing this lab is to observe the effects of various solute concentrations on osmosis in a potato. 2.
During osmosis, water moves from the side of the membrane where they are most concentrated to the side where they are less concentrated. If the concentration is equal on both sides, there will be no movement. 3. I hypothesize that the mass of the potato will decrease as the salt in the solution increases. This is because the solution around the potato will draw the water from the potato, causing it to decrease in size. Method: To begin this experiment, 1? teaspoons of salt was added to a beaker containing 100 mL of distilled water. This was the 7% solution. 0 mL of this solution was poured into a second beaker and 50 mL of distilled water was added. This produced the 3. 5% solution. 50 mL of this solution was added to a third beaker, then 50 mL of distilled water was added to make the 1. 75% solution. Out of the third beaker, 50 mL of the solution was discarded. In the fourth beaker, only 50 mL of water was added. After the solutions were mixed, a potato was cut into four sections. Out of each section, two pieces were cut, using a steak knife, into small blocks with the measurements of 10mm x 10mm x 40mm.
At this point, each piece measured 4,000 cubic mm in volume. Two potato pieces were then deposited into each solution. The potato pieces were then left in the solutions for 9 hours before being measured again. Results: Write “Results” as the heading for this section It was found that the potato pieces that were put into the highest salt concentration solution decreased the most in volume. The potatoes that were placed in the 3. 5% solution decreased in volume, but not as much as in the 7% solution.
Both decreased in size because the water from the potato cells were drawn out to the water solution. The potato piece that was placed in the 1. 75% solution virtually stayed the same size. This was the isatonic solution. The solution on the outside of the potato cell was the same as the solution on the inside, so no water moved. The potato that was placed in the distilled water alone increased in size because the water was drawn into the potato cell. This is because there was a higher concentration of water molecules on the outside of the potato than on the inside.
See table 1. Table 1. Potato core measurements | 0% salt solution| 1. 75 salt solution| 3. 5% salt solution| 7% salt solution| Beginning average volume (cu mm)| 4000 mm| 4000 mm| 4000 mm| 4000 mm| Ending average volume (cu mm)| 5220 mm| 3820 mm| 2940 mm| 2520| Percent difference (only if beginning measurements are different from each other)| 23%| 4. 5%| 27%| 37%| Discussion: Write “Discussion” as a heading for this section. Answer the following four questions – each in its own paragraph. 1.
Why did the results come out the way they did? Explain the biology behind the water movement into and out of the cells in each solution. Here’s another hint: This is where you show whether or not you understood what you were observing. You should consider each of the four solutions and explain what happened using the terms “hypertonic” “hypotonic” and “isotonic. ” In osmosis, the flow of the water from or to a cell depends on whether the cell is immersed in a solution that is isotonic, hypotonic, or hypertonic to the solution.
If the cell is isotonic to a solution, this means that the solute concentration of a cell and its environment is the same and therefore there will be no movement of water. If the solute concentration is lower than that of the cell, then water will flow into the cell, causing it to expand. If the solute concentration is lower than that of the cell then water will flow out of the cell, causing it to shrink. 2. Were your hypotheses right or wrong? Tell how those hypotheses would have to be modified in another experiment. My hypotheses were correct. . What mistakes (uncontrolled variables) might have affected how the results came out. Suggestion: Think of all the places in your method and materials where accuracy may not have been the best. Describe several. There could have been several variables that could have affected the results of this lab. One would have been if the salt measurements were incorrect. If more or less salt was added than realized, this would have caused the results to be incorrect. Another variable could have been the size of the potatoes being measured incorrectly.
If the pieces of the potatoes were not cut evenly and consistent with each other, but were recorded as being the same size, this would have caused the end results to be incorrect because the starting size was not measured properly. 4. Describe a real or hypothetical situation in your future professional life where you might apply what you have learned in this lab to a real-life situation. Before you begin, study your instructor’s directions on how to write a good application paragraph and review any feedback given by your instructor on other essays and labs relating to this important question.
Osmosis can be related to dehydration in humans. In the field of nutrition, keeping properly hydrated is often stressed and is important in order to function properly. Certain foods with a lot of salt can cause the body to become dehydrated if a person does not properly hydrate themselves. Dehydration can cause a many problems such as fatigue, dry mouth, dry skin, and even death because water is being drawn from those cells. I can use this information to explain to a client or patient the effects of not drinking enough water and the importance of staying hydrated.