Microbiology Lab Practical Exam 1 Questions & Answers Correct 100%

Recognize and Name Parts of the Microscope - Answer See Google Doc (#1) Ocular Lens - Answer Individual Magnification: 10x Total Magnification: 10x (10 x 1) Scanning Lens (Red) - Answer Individual Magnification: 4x Total Magnification: 40x (10 x 4) Low Power Lens (Yellow) - Answer Individual Magnification: 10x Total Magnification: 100x (10 x 10) High Power Lens (Blue) - Answer Individual Magnification: 40x Total Magnification: 400x (10 x 40) Oil Immersion Lens (White) - Answer Individual Magnification: 100x Total Magnification: 1000x (10 x 100) How to Calculate Total Magnifications - Answer Objective Lens x Specific Lens Recognize and Name Basic Bacterial Shapes - Answer See Google Doc (#2) Recognize and Name Basic Bacterial Arrangement - Answer See Google Doc (#3) Types of Media: Broth - Answer liquid media (inoculated with loop) Types of Media: Slant & Deep - Answer solid media (inoculated with loop or needle) Agar and its Function - Answer -solidifying agent for media -most bacteria cannot metabolize it -high melting point: 100 C -remains liquid until cooled to 42 C Making a Simple Stain - Answer 1) Using a clothespin, place the smear on a staining rack 2) Cover the smear with stain- (methylene blue or crystal violet or safranin) 3) Use different stain for each bacterial species 4) Let the stain sit on a slide for 60 seconds 5) Wash the excess stain with distilled water 4) Do not apply water directly to the smear; allow water to run through the slide 5) Gently blot the smear with bibulous paper 6) To record your observations, use oil immersion technique 7) You can put the oil directly on the smear; do not have to use a cover slip How to Make Smears - Answer -broth: insert the sterile loop into the broth, place 4-5 loopfuls of bacterial suspension on your slide, and spread the bacteria evenly over the slide -slant: place a loopful of distilled water in the middle of the glass slide, touch a cooled, sterile loop to the surface of the bacterial growth in a slant culture, the correct amount will barely be visible on the loop; do not scrape along the surface to gather a large clump of bacteria, mix the bacteria on the loop into the drop of water on your slide, and spread as thinly as you can, let air dry, and heat fix Purpose of Heat Fixing - Answer fixing denatures bacterial proteins and causes the cells to adhere to the glass slide- prevents the sample from being washed off the slide How to Make a Wet Mount Slide - Answer 1) place a drop of sample onto slide 2) cover slide with cover 3) view under microscope Characteristics Can Be Observed Using a Wet Mount Slide - Answer bacterial motility How to Recognize a Negative Stain - Answer -has negatively charged chromophore which is repelled from the cell surface -stains background instead of bacterial cells -cells appear clear against the background