Movement in and out of Cells (Beetroot) L ab Report Aim: The aim of this experiment is to e xplore the factors that affect the t he movement of materials in and out of cells by measuring light transmission. We will be using a beetroot plant to investigate the two factors; surface area of the beetroot and the change c hange in external environment, which affect the movement of beta lain(color pigment) out of the beetroot cells. Hypothesis: Beetroots have a color absorbing pigment called beta lain. This pigment gives the beetroot plant a strong red/purple color . This pigment is found within the vacuole of beetroot cells. The pigment gets removed from the vacuole as it’s external environment changes. I predict that the 4mL of 50% alcohol in which the beetroot would be placed in, would contain the most amount of pigment, which would have diffused from the beetroot’s vacuole. The alcohol would break the protein bonds increasing the permeability. Osmosis will then occur, the water molecules will move from a high water co ncentration(inside the cell) to an area of low water concentration(the solution). Hence, all the pigment will come out from the vacuole into the solution. Furthermore, when the light transmission transmission will be measured, I estimate the value of the amount of transmission will be low. This is because since the solution is expected to be of a dark color, most of the light will be absorbed, hence giving a low reading. Variables Dependent variable: The percentage of light t ransmitted. Independent variable: External environment Surface area Controlled Variables: Variable to be controlled How it is to be controlled The size of beetroot discs must be kept same Size of beetroot discs around 2mm each. The amount of solution for each type that the Amount of solution beetroots are placed in must be kept same. Each solution must be 4mL. The timings must be same the same. The Time beetroot pieces are left in each beetroot pieces should be put in all at the solution for same time for 15 minutes at least. The external environment of the experiment External environment the experiment is setup must be kept constant. Avoid any harsh conducted in heat or cooling temperatures. Materials Scalpel ruler 5 test tubes and a rack distilled water 25% and 50% Alcohol beetroot (Beta vulgaris) White tile for cutting 3 droppers ( for 25%alcohol 50% alcohol and water) thermometer
tripod stand and wire gauze bunsen burner water bath spectrometer
Method: 1. Use a ruler and scalpel to cut the cylinder of beetroot into 25 discs 2. Set up a boiling water bath using a beaker and a bunsen burner 3. Take 5 discs and cut them further into smaller pieces (these will be added into the t est tube with the LSA test) 4. Rinse the beetroot until the water turns clear 5. Label and prepare 5 test tubes as follow 6. Add 5 discs in each test tube, leave the tubes undisturbed for 15 m inutes as seen in Fig1.1 7. Shake the tubes gently and observe t he colors by placing them on a w hite tile 8. Then use the spectrometer to record the percentage of light transmitted. 9. Take a small amount of liquid from each test t ube into different cuvette and record the data, using Logger pro.
Fig1.1
Fig1.2
Data Table: Test Tube
Light Transmission (%)
Color
A
51.04
Light faint pink
B
56.76
Bright pink
C
3.14
Dark wine red
D
0.45
Bright pink darker than B
E
24.04
Light pink
Graph: The graphs of this experiment were produced using the Logger Pro software, when measuring the percentage of light transmission through each of the solutions. Conclusion: As can be seen from the results obtained my hypothesis was correct. The solution, which contained the most pigment was solution C. Solution C was 50% alcohol. The strong concentration of alcohol dissolves the cellular membrane and phospholipids in the beetroot cell. This then causes the permeability to decrease, causing osmosis to occur at a faster rate, which as a result makes the beta lain in the vacuole, exit out into the solution, making the solution dark colored. The light transmission through this solution was one of the lowest, however not the lowest, as expected. The percent of light transmitted through test tube C was 3.14%, whereas the light transmitted for test tube D, which had beetroot pieces in hot water, has a light transmission of 0.45%. We can assume that this is probably a methodical error as the color of the solution is lighter than test tube C. When the beetroot is placed in boili ng hot water, the heat denatures the cell membranes, also making osmosis occur at a faster rate. The beta lain pigment passes through easily from the vacuole into the solution, also giving it a dark pink color. Furthermore, we notice in test tube D when the surface area of the beetroot pieces is increased, even though the color isn’t dark, the light transmission is lower. This i s also because increasing the surface area means more beta lain is able to enter the solution. While measuring the light transmissions of each of these solutions, the darker the colors are the lower the light transmissions percentage as darker colors are absorbed while light colors are reflected. Evaluation: The reliability of the results was accurate to a certain extent. Since we were using electronic equipment and an electronic software to measure our results, there could have been some unavoidable errors. We were able to control most of our variables well. The size of beetroot discs was tried to kept at 2mm each, however this was not possible to keep 100% accurate, as we had to cut a total of 25 discs, all of which couldn’t be the same size. We did use a ruler to try and approximately make all pieces the same size as it would affect our result if some pieces were thick and some were thin. The amount of each solution was kept exactly the same. We used measuring cylinders to accurately measure the solution before placing the beetroot pieces inside. Lastly, we used stopwatches to keep accurate timings for the amount of time the beetroot pieces were left inside. We ensured that the beetroot pieces were only kept in for 15 minutes. Also the external environment of the experiment set up was kept constant. We conducted the experiment, keeping all test tubes away from any source of heat or air conditioning, which could have affected our results.
