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Biol 1000 Lab 3

York University
Uploaded: 5 years ago
Contributor: rahmansharam
Category: Biology
Type: Lecture Notes
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Filename:   Biol 1000 Lab 3.docx (16.3 kB)
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Credit Cost: 1
Views: 1700
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Last Download: 5 months ago
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Observing Effects of Solutions of Different Tonicity on the Leaf Cells of Rotala Indica Using Microscope Abdul Rahman 216574253 Laboratory C.11 Arnab Shuvo Assignment: Laboratory 3 - Plasmolysis: Investigating the Effects of Osmosis using the Microscope Date: October, 29th, 2018 2018 - 2019 SC/BIOL 1000 - Biology I - Cells, Molecular Biology and Genetics ( LAB) York University Material and Methods: In observation of a maximum concentration of 2M NaCl stock solution, the Rotala Indica’s leaf cells were assigned to a series of four different dilutions to determine at which concentration will plasmolysis occur. Initially, a compound microscope was set up at a 10X magnification to observe leaf cells undergoing plasmolysis process. Next, four separately-cut leaves of the aquatic plant, Rotala Indica, were used as the specimen in this laboratory. In addition, 15mL conical tube almost filled to the top with 2M of NaCl placed inside it was used as the solute. Alongside the mentioned solute, pond water was used as the solvent in the experiment. Coverslips and glass slides were to be used in accordance with the microscope. A pair of Pasteur pipettes, two rubber bulbs, scissors, and tweezers were provided in order to cut the leaves from each other and apply the solution to them. Furthermore, we were provided with four other 15mL conical tubes to create the four different solutions which would be applied to the leaves. Ultimately, a timer was used to record the time at which plasmolysis would occur. To start off, obtain a compound microscope and start to set up Kohler illumination. Due to 400x magnification previewing a blurry image, 10X magnification was used for a more clear view of the plant cells. Next up, it is necessary to have the dilution calculations done using the given C1V1=C2V2 concentration formula where C1 is the final concentration, V1 is the volume you want to make, C2 is the concentration of the stock solution and V2 is the volume of the stock solution required. Moreover, identify the 4 different working solutions. Due to the fact that there is only a certain amount of NaCl available, the concentration should not be over 0.8M that is also the amount used in this experiment. In addition, 5 mL is the maximum amount of the working solution to be made. And then using the formula provided above, determine the volume of solute (2M NaCl) and pond water needed. Next, using the four 15 mL conical tubes, create the four different dilutions from the data collected. Afterwards, place the four separately-cut Rotala Indica leaves on four different glass slides and using the Pasteur pipettes apply approximately 2 drops of the dilution to each of the leaves and start the timer. Next, place the glass coverslips on the leaves. After 5~10 minutes, place the glass slides on the microscope stage and adjust it so you have a clear view of the cell and using the compound microscope check to see if plasmolysis has occurred on any of the four dilutions. In our observation, dilution #1 with the volume of NaCl stock used was 1.25 mL and the volume of pond water used was 3.75 mL, experimented to have approximately ~ 60% of the cell experiencing plasmolysis in the Rotala Indica leaf cells. To confirm that plasmolysis has taken place, we had to observe the cells to see if it has shrunk and the cell membrane has separated itself from the cell wall and starts to shrink. After the experiment is done, switch off the microscope, clean up your station, and give the extra leaves left to your TA. Results: NaCl Stock Concentration Working Solution Concentration Volume of working solution to be made (mL) Volume of NaCl stock required (mL) Volume of water required (mL) Did Plasmolysis occur? (percentage %) 2 M 0.5 M 5 mL 1.25 mL 3.75 mL Yes (~60%) 2 M 0.75 M 5 mL 1.9 mL 3.1 mL Yes (~40) 2 M 0.8 M 5 mL 2 mL 3 mL No (~30) 2 M 1 M 5 mL 2.5 mL 2.5 mL No (~20) Table 1: Data recorded using the concentration formula plus the percentage at which the plasmolysis has occurred during the experiment, over 5 - 10 minutes period of time. Conclusion We determined that 2M of NaCl stock solution at a concentration of 0.5M triggers plasmolysis in Rotala Indica leaf cells. To verify this experiment we defined and approximated the plasmolysis process observing the cell membrane being separated from the cell wall when approximately ~60% of the cells have undergone the plasmolysis process.

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