Microscopy Worksheet (30 points)
Name:___________John Gibson_______________________
Section # (801-819)__________807A______________
Instructor Name:__________George Gikas_________________
(2 pts) How many oculars does your microscope have? What is the magnification of your ocular(s)?
1 set of binocular oculars (2 lenses). Magnification is 10x.
Think back to when you were moving the slide left-right and backwards-forwards.
(0.5 pt) When you move the slide slowly to the right. In what direction does the image in the ocular move? Is this the same or different than what the slide is doing?
Left
(0.5 pt) Is the image in the ocular inverted or the same relative to the specimen on the stage? (think about the “e” slide)
Inverted
(2 pts) What are two ways you can adjust the amount of light on your specimen?
Power knob of the light.
Iris diaphragm.
(2 pts) How do you focus your microscope? Why is it important to focus in low power and avoid using the course adjustment at higher power?
Use the coarse knob to raise/lower the stage at the lowest power.
It is important to use the low objective power because the low objective is short and give room to move the stage up/down.
Avoid using the coarse knob at higher power because the upward movement of the stage with the coarse knob is quite large and can press the glass side onto the objective, damaging both the objective and the glass slide.
Then use the fine focusing knob to fine-tune the focus.
(1 pt) What is the total magnification of a specimen when viewing the specimen with the 40x objective? Show your calculation
Answer: 400x
Calculation: 10x (ocular) * 40x (objective) = 400x .
(1 pt) Can you see the same amount of your ruler at high power as you did at low power? What is the relationship between field size and magnification?
No, the field size and magnification are inversely proportional.
(2 pts) Based on your measurements, what is your field size at 4x? Use that information to calculate the field size at 40x. Show your calculations.
5mm field size with 4x objective.
Mag1*F1=Mag2*F2
4x * 5mm = 40x * F2
F2 = 4x * 5mm / 40x = 0.5 mm
(4 pts) Define:
Isotonic
The environment solution’s solute concentration is the same as the cell cytosol’s solute concentration.
Define hypertonic
The environment solution’s solute concentration is higher than the cell cytosol’s solute concentration.
Define hypotonic
The environment solution’s solute concentration is lower than the cell cytosol’s solute concentration.
Define plasmolysis
The environment solution’s solute concentration is higher than the cell cytosol’s solute concentration. The cell or organelles of the cell shrink due to water leaving.
(2 pts) What happened to the Elodea cells when you added distilled water to the slide vs. the 10% NaCl? Describe the choloroplasts.
Distilled water: The chloroplasts are pushed and moved toward the cell wall.
10% NaCl: The chloroplasts bunched up at the center of the cell.
(4 pts) What happened to the Elodea cells when you added tank water back to the slide? Based on some research, is plasmolysis reversible? Why was/wasn’t it in your observations? Why or why not?
Adding tank water reverses the chloroplasts’s movement.
The research paper https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4844282/ says plasmolysis is reversible. It also says that the vacuole drives the movement of the organelles at the center of the cell.
I observed the reversal of the plasmolysis readily because the cell was robust enough and no damage was done to the cells during plasmolysis.
The research paper says that microtubules need 24 hours to restore to their original state after plasmolysis. However, other cytoskeleton components may be restored to their original shape much quicker.
(2 pt) Using your averaged data you are going to compare it to the average class data. Frist, make sure you have your triplicates averaged. Second, average the class data for each solution. Display this as a table and insert it at the end of the worksheet.
Table A. Average Percent Weight Change Of Potatoe Osmosis
Reference: Data collected can calculated by the authors of this report.
Legend: The potatoes are of 1 cm diameter cylinders cut into 1 cm height for each tube’s osmosis experiment.
(4 pts) Using the data from the table make a bar graph with both your data and the class data the solutions on the x-axis and that percent change on the y-axis. Insert the graph at the end.
Figure A. Average Percent Weight Change Of Potatoe Osmosis vs. NaCl Concentration
Reference: Data produced by authors and classmates of this report
Legend: Blue bars are data of the author’s group. The red bars are class average data.
(3 pts) Describe how close your averaged data is to the class average data. What conclusions can you draw about data generated once, in triplicate, or many times?
My average percent change data is close to the class average percent change data. Within in 10 percentile points difference.
I conclude that single individual percent change has large differences among the same NaCl concentration. For example, 3b’s 4.0% change is twice as large as 3a’s 1.9%.
The triplicate data average makes the deviation of individual experiments smaller, for example, 3a/3b/3c average at 2.8%, and 3b’s 4.0% is not as big a deviation between 1.9% and 4.0% . So, triplicate data average is more representative of the general result.
More repeats produce more accurate results.
The many experiments by the whole class make a yet, better representation of the experiment result. The class average trend has a smooth slope down as the NaCl concentration increases. My group’s average trend has a sharp zig-zag turn, which does not physical sense and is likely experimental procedure variations, such as drying the potato too little or too much before weighing.
Comments
Post a Comment