Microbiology Lab Exam 1 Study Guide | With Complete Questions and Answers (Graded A+)

If an autoclave is working properly what color will the BTsure vial be after a 15min autoclave cycle? - ANSWER - Purple How do you use and Enteropluri tube? - ANSWER - Read the positive agar windows and circle the corresponding numbers. Add up each grouping of numbers to obtain a 5 digit biocode. Look up the biocode and find your unknown bacteria. What is the difference between a pure culture and a mixed culture? - ANSWER - A pure culture contains a single bacteria and will present itself as a distinct colony morphology throughout a streak plate. A mixed culture is characterized by 2 or more bacterial organisms and is presented on a streak plate as 2 or more dissimilar colony morphologies. What are some reasons you would see a completely dark field when looking through a micorscope? - ANSWER - The power is off or the machine is not plugged in, the objective is not clicked into place, or the bulb is burned out. Why do we use immersion oil? - ANSWER - Immersion oil increases the resolution, by decreasing the light refraction, making the image appear sharper. when viewing a smear with the oil immersion lens the final magnification is - ANSWER - 1000x;10x ocular x 100X objective what is the purpose of heat fixing - ANSWER - kill the bacteria, adhere to glass anddenature the proteins of bacteria name oneof the stains or regents used in the gram stain procedure - ANSWER - gram crystal violet, gram iodine, gram sfaranin, 95% ethanol why are aseptic techniques used in the lab? - ANSWER - to ensure that we do not contaminate what we are working with as as to ensue that we do not acciently inoculate ouselves. example of aseptic techniques are flaming the loop/needle sterilizing it, breifly flaming the test tube before and after obtaining the sample.