Portage Learning / BIOD 171 Lab Exams 1-8 1 1. What three elements are used in an autoclave to sterilize equipment? heat, pressure, and steam 2. What is the minimum temperature an autoclave must be set at to achieve sterile condition? 125°C 3. If you are working in a lab in which an autoclave is not available, and you are pressed for time, which would you chose to best sterilize your equipment? Hot steam or hot air? Explain why you chose your answer. Hot steam is the best choice as you can achieve a sterile environment in a matter of minutes whereas hot air will take several hours to achieve the same effect. 4. What type of incubator is pictured below? Fixed incubator Lecture Exams Portage Learning / BIOD 171 Lab Exams 1-8 2 Answer the following questions. 1. At what temperature is the fixed incubator set to, as presented in the lab video? 37°C 2. At what temperature should you refrigerate bacterial samples? Explain why this is beneficial. 4°C. This temperature slows bacterial growth and prolongs the life of the sample. 3. What are the FOUR types of gloves presented in the lab video? Latex, Nitrile, Thermal cold, Thermal heat 4. What THREE rules were discussed in regards to lab safety that would protect you and others from contamination? 1. Never eat or drink in the lab 2. Always wear appropriate PPE 3. Never leave the lab wearing PPE 5. What are the main sections that should be found in a lab notebook? Name at least 4. Objective, Procedure, Notes, Results and Deviations Answer the following questions. 1. You are a lab instructor and Paul Smith has turned in his lab notebook for you to grade the lab experiment #2 on microscopy. Based upon what was covered in the lab video, how should Paul have entitled his lab experiment? PS02 Microscopy 2. You arrive to your first day of work at a new lab. You are taking over for someone who took a new job at another lab. Your boss informs you that because of time restraints, this person did not exactly follow the experimental protocol. In order to proceed, you must know what he did differently. (1) According to the lab lecture, under what section of his notebook would you look to find the experimental steps? (2) As changes to the experimental steps were made, what are these differences called and how should it appear in the lab notebook? Portage Learning / BIOD 171 Lab Exams 1-8 3 (1) Procedure—this is where the steps for the experimental protocol are recorded. (2) Deviations. All deviations should be written in red to immediately bring attention to the changes in the protocol. Answer the following questions 1. Identify the part of the microscope indicated by the arrow. Neck (or arm) 2. Identify the part of the microscope indicated by the arrow. Stage 3. Identify the part of the microscope indicated by the arrow. fine focus Portage Learning / BIOD 171 Lab Exams 1-8 4 Answer the following questions 1. You are about to study a bacterial sample under a light microscope. You look into the oculars and see two circles. What adjustments need to be made? Compress or expand the oculars until a single circle can be seen while using both eyes simultaneously. 2. What 2 parts of the microscope contributes to the total magnification to your sample? Objective and oculars (eyepiece) 3. As you looking through the microscope you wish to dim (or limit) the amount of light entering into the eyepiece—what component of the microscope other than the light source itself can be adjusted to make these modifications? Diaphragm Answer the following questions 1. What objective power is best suited if you are uncertain what the sample is and where to begin? 4x (or lowest power objective) 2. You are viewing a sample of bacteria that is 3 mm in diameter through a 40x objective lens. The eyepiece has a magnification power of 10x. What size will the sample appear through the eyepiece? 1200 mm in diameter (or 400x’s larger) 3. Based on the microscope shown in the lab lecture, which objectives would NOT require placing oil on the slide? 4x, 10x and 40x Answer the following questions. 1. List the 4 main steps used to prepare a WET mount and indicate which (if any) step is optional. 1 – Clean slide 2 – Circle area on slide with wax/hydrophobic pen Portage Learning / BIOD 171 Lab Exams 1-8 5 3 – Apply organism to slide Portage Learning / BIOD 171 Lab Exams 1-8 6 4 – View under microscope *Note: there are no optional steps in the wet mount. 2. When preparing a glass slide for a dry mount, what cleaning solution was used? 70% ethanol 3. You wish to study the motility of a particular bacterium. What type of mounting technique would you use? Explain your answer. A wet mount technique is the best technique to use when studying motility of an organism because the sample remains viable (heat fixing kills the sample). 4. What dye do Gram-negative bacteria primarily retain? Safranin Answer the following questions. 1. Why do Gram-negative bacteria stain red? Gram-negative bacteria have a thin peptidoglycan layer in their cell wall. During the alcohol rinse step, the cell wall cannot retain the crystal violet dye. It will be washed away. The cell wall will then absorb the counter stain, safranin. 2. Identify the stain and shape of the bacteria pictured below.