Copy of Lab 2 Equipment Post-lab_FA22

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Feb 20, 2024

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Post-lab Assignment LAB 2: Equipment Use Bio 1AL Fall 2022 Last Name __________Kim______________ First Name ___________Juliana___________ Lab Section #_____223______ Lab 2 Post-Lab 1) Based upon your absorption spectrum of DCPIP, record your value for λ max . (0.5 pt) Λ max : 606.3 2) DCPIP standard curve a) Graph the quantitative relationship between absorbance and DCPIP concentration using the DCPIP standard curve absorbance values that you recorded. See the Correlation and Regression Analysis page in bCourses. Use an xy scatter plot chart type in Excel, and fit the data with a linear trendline. Show the equation of the trendline and R 2 value on the graph. Save the graph in Excel as an image ( Ctrl Click on the graph > Save as Picture or take a screenshot ) and paste the image below. (1 pt) X-axis: DCPIP Concentration ( µM) Y-axis: Absorbance (nm) b) Describe in your own words what your R 2 value means. (0.5 pt) Our R squared value came out to 0.9627 meaning that 96.27% of the variation in absorbance values is explained by the linear relationship with DCPIP values. 2-1

Post-lab Assignment LAB 2: Equipment Use Bio 1AL Fall 2022 c) Use your standard curve to determine the concentration (in µM) of the unknown DCPIP solution. Report the absorbance that you measured for the unknown DCPIP solution. Use the equation of the trendline for your calculation, and show your work. Include units. (0.5 pt) Absorbance of unknown DCPIP solution: ______0.834 nm_______ Concentration of unknown DCPIP solution: ____26.49 µM _____ (Show your work below). Y = 0.0255x - 0.1584 (0.834 nm) = 0.0255 x - 0.1584 0.6756 = 0.0255x X = 26.49 µM 3) Pipetting : Record your five values for pipetting 100 μL and those of your lab station partner. Note if you did not have a station partner then get the data from another student. If there were three students in your group, then please record the data of one of them. a) You will be running a t-test on your data. State the null hypothesis for the t-test. (0.5 pts) We hypothesize that the difference in the group means will be zero. b) Calculate the mean, standard deviation (see Excel Graphing Resources), and percent error from the expected weight for the 100 μL sample. Run an Independent Sample t-test using VassarStats, and record the relevant values below. See the Comparing Two Means page in bCourses for guidance on performing and interpreting the t-test. (2 pts) Your data Lab partner’s data Observed weights (g) 0.0976 0.0981 0.0999 0.0975 0.1 0.1002 0.0994 0.0989 0.1001 0.0999 Mean weight (g) 0.0994 0.09892 Standard deviation (g) .00104 0.00115 Percent error from expected (%) 0.6% 1.08% t-test results t = __0.69__, df = __7.92__, p (2-tailed) = __0.5086__ c) Based on the t-test results, what should you do with regard to the null hypothesis? (circle one) (0.5 pt) Reject the null hypothesis Fail to reject the null hypothesis 2-2

Post-lab Assignment LAB 2: Equipment Use Bio 1AL Fall 2022 4) In lecture, micropipette accuracy and precision were discussed. (0.5 pt) Which statistical measurement is most relevant and likely to be altered by errors arising from problems with: Pipettor accuracy ? (Circle/Highlight one): Mean Standard Deviation Pipettor precision ? (Circle/Highlight one): Mean Standard Deviation 5) Reticle calibration . Complete the table below using the data you recorded in Table 3 of the Lab 2 Procedures. (1.5 pt) Total Magnification # of Subdivisions in 100 μm Calibration (μm) = distance between each subdivision 100X # = ___10____ 100 μm / # = ___10___ μm 200X # = ___19___ 100 μm / # = __5.26__ μm 400X # = ___39____ 100 μm / # = _2.56_ μm 6) Depth of Field . Examine the slide with the solid glass rod and hollow glass tube. In the left circle, draw the appearance of a solid rod when the 20X objective is focused in the midpoint of the solid rod. In the right circle, draw the appearance of the hollow tube when focused in the midpoint of the hollow tube. Include scale bars labeled with the distance that they represent . (1 pt) Drawing instructions: If you hand-drew the drawings, you can take a picture of the drawings and insert the image below. You may also double click on the image below and complete the drawings using the Google Drawing tools. Which is on top : the solid rod or the hollow tube? (0.5 pt) (Circle/highlight one) Rod Tube 2-3

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