Microbio 150 Lab exam 1 PVCC 2025 Questions & Answers with 100% Correct Answers | Verified

When preparing to view a specimen on a compound microscope in the lab, one should __________ begin with the 4x objective - Always Where should used gloves be disposed of in the microbiology lab - In the bio-hazard waste container Before putting a dust cover over the microscope and placing it in the cabinet, which objective lens should be rotated over the stage - 4x On the microscope, what concentrates the light on the specimen? - Condenser lens On the microscope, what bends light passing through the specimen to create a real image - Objective lens On the microscope, what allows for more or less light to be directed onto the specimen - Iris diaphragm On the microscope, what gives you clarity of the image - Resolution Why is desiccating your inoculating loop important? When should this be done? - To ensure it is sterilized, done so no cross contamination happens During an aseptic transfer, when do you pass the mouth of the test tube through the flame? - Before and after dipping loop in During the broth to slide aseptic transfer, a __________ was used to obtain a pure culture from a __________. - Loop, broth Prior to staining, smears of microorganisms are heat-fixed in order to - Attach it firmly to the slide The term that refers to the purposeful addition of microorganisms into a nutrient medium is - Inoculation True or false: In the microbiology lab, it is acceptable to move your loop around while waiting for it to dry. - False Which stain was used during the negative staining procedure? - Nigrosin Which stain was used during the simple staining procedure? - Methylene blue True or false: During a negative stain, the bacteria are heat fixed. - False Bacteria in the Mycobacterium genus have the presence of what component in the cell wall that causes them to be acid-fast? - Peptidoglycan After the decolorizer has been added, gram-positive organisms appear __________ and gram-negative organisms appear __________. - Purple; colorless Why is iodine (or a mordant) used in the Gram staining process? - It forms a complex with crystal