Microbiology Lab Practical 1 (TAMUCC) Exam Questions and Answers 100% Pass

Microbiology Lab Practical 1 (TAMUCC) Exam Questions and Answers 100% Pass How is total magnification calculated? - Multiply the ocular lens (10x) by the objective lens 10x*10=100x 40x*10=400x 100x*10=1000x OCULAR TIME OBJECTIVE what is the function of immersion oil when using the oil immersion objective? - the immersion oil allows for magnification and increases the contrast of the specimen What is meant by the term parfocal? - Once the lens is focused on a particular area it will remain focused on the particular area regardless of changing the objective why aren't the magnifications of both lenses of binocular microscope used to calculate total magnification? - Because the image only goes through one ocular to reach both eyes Why is the 10x placed in position when the microscope is stored or carried? - The low-power objective is farther away from the stage than the other objectives so the lens is less likely to get scrapped during handling. What is an aseptic technique? What is its importance? Why do you always have to do it in the microbiology lab? - -Microbiologists use aseptic technique for a variety of procedures such as transferring cultures, inoculating media, isolation of pure cultures, and for performing microbiological tests. 2 | P a g e Created by Katelyn Whitman © 2025, All Rights Reserved. 100% PASS GUARANTEE -Proper aseptic technique prevents contamination of cultures from foreign bacteria inherent in the environment. what are some aseptic techniques used when transfering cultures from plate to broth tube and agar slant? - 1. Prepare your desktop by swabbing down its surface with a disinfectant. 2. Wash your hands 3. With a marking pen, label a tube of sterile nutrient broth with name, date and specimen 4. Sterilize the inoculating loop by holding it over the flame of a Bunsen burner until it becomes bright red. The entire wire must be heated. what is a culture medium? - An artificial environment that provides water and nutrients for the microorganism Types of culture media used in the lab based on form - NA (Agar) Slant: solid at 50C or above, if below liquid NB tubes: liquid, cloudy, yellow NA Agar Plate: solid cloudy yellow What is pure culture? - population of cells derived from a single cell What is a mixed culture? - microbial culture consisting of two or more species How do you sterilize an inoculating needle or loop? - by putting it in the flame until the needle turns orange to know that it has been sterilized Explain why petri dishes labeled on the edge of the bottom place and not on the lid? - After the culture medium is set, and streaked with the required microbe/stock, the lid is put on and the petri dish is incubated upside down to minimize contamination. So, it is easier to read the label on the bottom. Also, if the lids are accidentally exchanged, it will be less of a problem. 3 | P a g e Created by Katelyn Whitman © 2025, All Rights Reserved. 100% PASS GUARANTEE why are inoculated agar plates incubated in an inverted position? - To prevent condensation of water on the lid. Water can mix in with the bacteria not allowing for individual colony growth. How is bacterial growth determined in Agar Plate? - in the agar plate the bacteria is spread using either a quadrant streak or t-streak which allows the bacteria to grow in isolated colonies and the growth can be determined by -size, shape, margin(smooth/rough), surface(dull/shiny/soft), elevation, texture, optical properties, and color How is bacterial growth determined in Agar Slant? - growth patterns can be determined by texture, optical properties, margin(smooth/dull), and color. How is bacterial growth determined in Agar Broth? - growth patterns can be determining if it is turbid, any sediments, pellicle (rim at the top of the broth)