BIO201 Lab 4

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Lab 4 Diffusion and Osmosis BIO201L Student Name: Thanh Hong Di Nguyen Access Code (located on the lid of your lab kit): AC-XOT0FS Lab Report Format Expectations Utilize college level grammar and professional formatting when completing this worksheet. Submissions without proper formatting, all required photos or sufficient responses will be rejected. Pre- lab Questions 1. Define the following terms. a. hypertonic solution: Hypertonic solution indicates a higher or excessive concentration of solution compared to the cell. It has a high solute and low water concentration. b. hypotonic solution: Hypotonic solution has a lower concentration of solution compared to the body fluids. It has a low solute and high water concentration. Therefore, there will be a water movement from the outside to the inside of the cell; this makes the cells to become swelling. c. isotonic solution: Isotonic solution has the same or equal of concentration of the solution between the inside and outside of the cells. 2. Define osmotic pressure. As we understand, osmosis is the movement of the water from the low concentration of solute to the high concentration of solute. Its osmotic pressure is the force needed to stop the osmosis across the semipermeable membrane. 3. Explain what would happen to a cell placed in a hypertonic solution. If a cell is placed in a hypertonic solution, the cell will be shrunk. This is because the solvent from the inside of the cell will be pulled out from the low concentration of solute to the higher concentration of solute which is located outside the cell.

Lab 4 Diffusion and Osmosis BIO201L EXPERIMENT 1: DIFFUSION THROUGH A LIQUID Introduction Questions 1. State the molecular weight of the blue dye in grams per mole. Molecular weight = 793 g/mole. 2. State the molecular weight of the red dye in grams per mole. Molecular weight = 496 g/mole. 3. Why does this experiment require two dyes of different molecular weights? Answer this question, ensuring you explain the purpose of these two dyes in relation to the experiment. Molecular weight indicates the mass of the molecule. As it mentioned, these two dyes have different molecular weights. The purpose of these two dyes in this experiment allows us to understand the relationship between the molecular weight and rate of difusion. It determines whether the heavier or lighter weight of molecules diffuses faster in a viscous environment.

Lab 4 Diffusion and Osmosis BIO201L Data and Observations Record the diameters you observed for both dyes in the table below. Table 1: Rate of Diffusion in Corn Syrup Time (sec) Blue Dye Red Dye 10 0.7cm 1.2 cm 20 1.0 cm 1.5 cm 30 1.2 cm 1.8 cm 40 1.2 cm 2.0 cm 50 1.3 cm 2.1 cm 60 1.4 cm 2.2 cm 70 1.6 cm 2.3 cm 80 1.6 cm 2.4 cm 90 1.7 cm 2.4 cm 100 1.8 cm 2.5 cm 110 1.8 cm 2.5 cm 120 1.9 cm 2.5 cm Calculate the speed of diffusion and present this, along with the required data, for both dyes below in Table 2. To calculate the hourly diffusion rate, multiply the total distance diffused by 30 . Table 2: Speed of Diffusion of Different Molecular Weight Dyes Structure Molecular Weight Total Distance Traveled (mm) Speed of Diffusion (mm/hr)* Blue Dye 793 g/mole 19 mm 570 mm/hr Red Dye 496 g/mole 25 mm 750 mm/hr Results and Discussion 1. Examine the plot below. How well does it match the data you took in Table 1?

Lab 4 Diffusion and Osmosis BIO201L This plot is comparative or closely matched to my data in Table 1. They both show similar results in determining which dye is faster than the other and how the relationship between the molecular weight and the rate of diffusion in corn syrup. However, the diameters of dye diffusion I collected are much higher than the illustrated data. I believe this is because of the different pipettes (mine is a small plastic pipette, and it is different from the professional micropipette. My pipette with a large diameter end produces a big drop; therefore, the numbers are much higher. 2. Which dye diffused the fastest? Both data show the red dye diffused faster than the blue one. 3. How does the rate of diffusion correspond with the molecular weight of the dye? According to both data, the red dye with the lower molecular weight diffuse faster than the blue one with the higher molecular weight. Both dyes diffused rapidly for the first 30 seconds. . 4. Does the rate of diffusion change over time? Why or why not? After the first 30 seconds, they reach a plateau in which it spreads very slowly, not increasing promtly as before or decline. This is because the dye becomes less concentrated as it diffuses to corn syrup. EXPERIMENT 2: DIFFUSION - CONCENTRATION GRADIENTS AND MEMBRANE PERMEABILITY Introduction Questions

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