Microbiology LAB Exam #1 Questions and Answers 100% Pass

Microbiology LAB Exam #1 Questions and Answers 100% Pass Microscope- The Condenser - focuses the light ging into the objective lens Microscope- The Iris Diaphragm - adjusts the amount of light going into the objective lens Microscope- Nosepiece - holds the objective lenses and rotates to change from one objective to another Microscope- Coarse Objective Knob - moves the stage larger distances to help get the object in focus Microscope- Fine Adjustment Knob - moves the stage smaler increments to help get the object in better focus Microscope- Objective Lens - magnifies the object. It is located near the object. Microscope- Occular Lens - magnifies the image of the object from the objective lens. It is located near the eye. Steps in using the microscope - 1) scanner power in place 2) place slide of specimen stage in place with stage clips 3) Using the course adjustment knob, raise the stage all the way up and then down slowly until you can see image of specimen 4) Readjust with fine adjustment knob Describe the purpose of the oil immersion lens - Used when oil is added to the slide. Oil must touch the object and objective lens to that the light does not refract futher 2 | P a g e Created by Katelyn Whitman © 2025, All Rights Reserved. 100% PASS GUARANTEE Parfocal - Parfocal microscopes are able to move from one objective to the next and still be in focus due to the length of the objective lenses Resolution - The ability to distinguish between two objects that are very close together. What is resolving power? - The measurement of resolution What are two ways to increase resolving power? - 1. By decreasing the wavelength of light (using a blue filter) 2. Increasing the numerical aperature What units are used to express resolving power? - nm or nanometers What is better, smaller or larger resolving power? - Smaller is better Light microscopes have a 200nm resolving power Electron microscopes have a .2nm resolving power What is chromatic aberration? - The effect when many colors are seen toward the edge of the microscope field of vision (like a prisim) How are microscopes corrected for chromatic aberration? - With a special achromatic lens (corrected for red and blue light) or by using a blue filter. The lab has blue filters in their microscopes which also increase resolution. Describe the process of making a wet-mount slide - 1) Add the specimen to the slide 2) Touch the edge of the cover slip with one edge of drop of specimen. 3) Let the cover slip drop gradually to the slide, covering the drop of specimen. Describe the purpose of making a wet-mount slide - To be able to see living organisms under the microscope in their natural state. 3 | P a g e Created by Katelyn Whitman © 2025, All Rights Reserved. 100% PASS GUARANTEE What is the advantage of using a wet-mount slide? - Can see movement and determine if microbes posses their own method of motility. Can also see the actual shape and arrangement of microbes. What is the dis-advantage of using a wet-mount slide? - The movement is very fast, microbes are transparent. Must use a "dark-field stop". What is a producer? - Are autotroph organisms that make their own food (through photosynthesis). What structure is an indicator of a producer? - Chloroplasts is an indicator that an organism is a producer. An example of a producer is what? - Algae are producers that are found in a pond. What is a consumer? - They are heterotrophic organisms that get their food from another source (nonphotosynthetic) Examples of a consumer are what? - Protozoans such as paramecium and multicellular animals like rotifers or daphnia. What is osmosis? - The diffusion of water What organelle of protozoans responds to osmosis? - The cell membrane is where diffusion occurs. Why do we use asephtic technique of bacteria? - To obtain pure cultures and to prevent contamination of pure cultures. When is it best to use a broth? - When you want to grow a lot of bacteria. When is it best to use a agar slant? - To subculture bacteria that does not need to be "isolated" and to store the bacteria for several months. When is it best to use an agar deep? - Used to determine motility and oxygen requirements of bacteria. 4 | P a g e Created by Katelyn Whitman © 2025, All Rights Reserved. 100% PASS GUARANTEE Describe the process of aseptic transfer from broth to agar slant - 1) Flame your loop 2) Hold broth at 45 degrees and pull off cap 3) flame lip of tube 4) obtain loopful of culture 5) flame lip of tube and replace cap 6)pull cap flame lip of slant 7)insert loop and zig-zag up the butt of the slant 8) flame lip of slant and insert cap Describe the process of aseptic transfer from broth to agar plate - 1) Flame your loop 2) Hold broth at 45 degrees and pull off cap 3) flame lip of tube 4) obtain loopful of culture 5) flame lip of tube and replace cap 6) open plate and zig-zag loop (without digging) across the surface of the agar 7) replace lid to plate Why is the top of the tube heated? - To force out air and keep contiminants from settling inside. When is a needle used rather that a loop when transferring bacteria? - 1) To pickup specific colonies without accidently touching other colonies of other species nearby. 5 | P a g e Created by Katelyn Whitman © 2025, All Rights Reserved. 100% PASS GUARANTEE 2) Also used to break up large chucks of bacteria 3) Used to inoculate agar deeps define and identify the following broth culture growth patterns -Flocculant - clumps of growth throughout define and identify the following broth culture growth patterns -Pellicle - A film of growth at the top of the broth define and identify the following broth culture growth patterns -Sediment - Precipitate that falls to the bottom of the tube define and identify the following broth culture growth patterns -Turbidity- - Growth evenly distributed throughout. define and identify the following agar slant growth patterns -Arborescent- - branched growth from the original streak define and identify the following agar slant growth patterns -Beaded - Isolated colonies to