40 Post Lab Quiz 1 Pipets and Pipetting Post Lab Quiz 1 What volume does the pipet below contain this is a 5mL pipet Just type in the volume not the units e g 3 7 not 3 7 ml 2 What type of pipet is shown below Correct Answer 3 0 A Volumetric B Serological C Mohr D Mechanical 3 What is the size of the pipet shown above A 1 ml B 2 ml C 5 ml D 10 ml Correct Answer B Correct Answer A Your Response D 4 What volume does the pipette above contain Just type in the volume not the units e g 0 50 not 0 50 ml Correct Answer 0 67 Your Response 6 7 Correct Answer C 5 You are asked to pipet 2 6mL into a reaction mixture There are four pipets on the lab bench A B C D Which one do you use A P100 micropipet B 1 0mL pipet 6 Why did you choose this pipet C 5 0mL pipet D 10 0mL pipet Correct Answer Greatest accuracy Your Response its the smallest pipet just big enough to hold 2 6mL 7 Arrange the following steps in a possible correct order for calibration of the spectrophotometer 1 is first and 6 is last Insert blank and set Transmittance to 100 A Switch MODE to Absorbance B C Remove blank and insert sample D Set the wavelength to 510 nm E Set Transmittance to 0 sample holder is empty F MODE Transmittance 8 Which of the following solutions is the least concentrated Correct Answer A 6 B 4 C 5 D 1 E 3 F 2 Your Response A 5 B 4 C 6 D 2 E 3 F 1 A 1 B 2 C 3 D 4 Correct Answer B 9 As the concentration of a colored solution the value A B C Increases absorbance increases Increases transmittance increases Increases absorbance decreases D Decreases absorbance increases E Decreases transmittance decreases Correct Answer A 10 Using the standard curve shown below for cobalt chloride solutions estimate the molar concentration of cobalt chloride for a solution that has an absorbance reading of 0 4 odu A B C D E 02 03 04 05 06 F G H I 07 08 09 1 41 Post Lab Quiz 2 Enzymes 1 Use the standard curve below for cobalt chloride concentration to estimate the concentration of a cobalt chloride solution that had an absorbance reading of 0 7 ODU Correct Answer G Figure 1 Absorbance of cobalt chloride vs molar concentration of solution A 0 04 M B 0 06 M C 0 1 M D 0 05 M 2 The relative color intensity of the solution in our experiment s reaction tubes Select one is a consequence of production of Benzoquinone is an indicator of enzyme activity A B C may differ depending on the pH temperature or the concentration of the substrate D all of the above 3 Enzymes catalyze reactions by adding energy Correct Answer D Correct Answer D Correct Answer False 4 Which of the following is most correct for an enzyme catalyzed reaction A The shape of the enzyme is important but the shape of the substrate is not important B The shape of the enzyme is not important but the shape of the substrate is important C Both shape of the enzyme and the shape of the substrate are important D Neither shape of the enzyme nor the shape of the substrate are important Correct Answer C 5 The following graph shows the results of an enzyme catalyzed reaction experiment Figure 2 Millimoles of product vs reaction time in seconds The rate of the catalyzed reaction is millimoles per minute 6 The hypothesis is rejected when treatments are meaningfully different from one another A Alternative B Experimental C Null D Universal 7 The alternative hypothesis states that the treatment or treatments will have no effect on the process being investigated Correct Answer 0 1 Your Response 01 Correct Answer C Correct Answer False 42 Post Lab Quiz 3 Osmosis 1 Determining the Relative Osmotic Concentration of Plant Cells Below is the graph of experimental results determining the osmotic concentration of plant tissue At what molarity is the sucrose solution isotonic to the cells Solve for x when y 0 A 0 300 M B 3 202 M C 0 3123 M D 0 3123 M 2 What is the independent variable in this experiment 3 What is the dependent variable in this experiment Correct Answer D Correct Answer Sucrose concentration Correct Answer Percent Change in Mass 4 Determination of Diffusion Rate of Molecules of Varying Size and Polarity across the Cell Membrane Below is a bar graph of experimental results examining the permeability of RBCs to various alcohols The plots are of hemolysis times in seconds Shown in the plot are the means S E for 3 replicates Are there any statistically significant differences that the data shows A Only the difference between methanol and propanol is statistically significant B Only the difference between methanol and ethanol is statistically significant C The difference between propanol and the other alcohols is statistically significant D There are no significant differences shown in the data 5 What is the independent variable in this experiment 6 What is the dependent variable in this experiment 7 Why are replicates important in this experiment Correct Answer C Correct Answer Alcohol type Correct Answer Hemolysis time Correct Answer to be able to assess if the differences are meaningful Your Response Replicates help to determine whether the difference detected is experimental error or a difference which is related to the variable being manipulated The replicates in this experiment are important to increase the reliability of the data and determine any significant differences between the alcohols 43 Post Lab Quiz 4 Osmosis 2 1 If two solutions contain equal concentrations of solute they can be described as in terms of their respective osmotic concentrations isotonic A B hypotonic C hypertonic Correct Answer A 2 The following graph shows the change in mass for a tissue sample in various concentration of sucrose solutions At what molarity is the sucrose solution isotonic to the cells A 18 03 M B 0 34 M C 0 40 M D 3 05 M 3 In the experiment in question 2 what is the dependent variable A Sucrose concentration B Time C change in mass D Molecular weight 4 If you soak potato slices in 0 1 M sucrose solution sucrose and water for one hour and you find that they weigh more after being soaked i e they gain mass what can you conclude about the potato cells A B C they are hypotonic compared to the solution they are isotonic compared to the solution they are hypertonic compared to the solution 5 Certain molecules have difficulty crossing from one side to the other of cellular membranes If you were designing a drug that you wanted to easily pass through the cellular membrane would you try to make the compound more or less hydrophobic A Less B More Correct Answer B Correct Answer C Correct Answer