Microbiology Chapter 3

You have been given an unknown sample with an unknown number of bacterial cultures from your course instructor to identify. Determine the correct sequence of steps you need to adopt in order to identify your unknown. Gram staining Microscopic examination Isolate colonies (4 quadrant method) Endospore/Flagella/Capsule staining and/or Biochemical testing 1, 3, 2, 4 1, 2, 3, 4 3, 1, 2, 4 2, 1, 4, 3

3, 1, 2, 4

You have been given an unknown sample with two bacterial cultures from your course instructor to identify. Determine the correct sequence of steps you need to adopt in order to identify your unknown. Gram staining Microscopic examination Isolate colonies (4 quadrant method) Endospore/Flagella/Capsule staining and/or Biochemical testing 3, 1, 4, 2 1, 3, 2, 4 3, 1, 2, 4 3, 2, 1, 4

3, 1, 2, 4

Select the correct sequence of chemicals used in the Gram stain procedure. Ethanol Safranin Crystal violet Gram's iodine 2, 1, 4, 3 3, 4, 2, 1 3, 1, 2, 4 3, 4, 1, 2

3, 4, 1, 2

Which of the following microbes can be viewed easily with a bright-field microscope once they have been stained? (Select all that apply) Treponema pallidum Candida albicans Escherichia coli Staphylococcus aureus

Candida albicans Escherichia coli Staphylococcus aureus

During dark-field microscopy, the black specimen is surrounded by an illuminated background. True False

False

? is defined as the ratio of image size to object size.

Magnification

Which of the following is an advantage of scanning electron microscopy? SEMs are expensive and large. Most SEM samples require minimal preparation actions. SEMs carry a risk of radiation exposure that is associated with the scattering of electrons. The preparation of samples may result in artifacts.

Most SEM samples require minimal preparation actions.

Select the CORRECT statement. (Select all that apply) Specimens that are examined using fluorescence microscopy may be naturally fluorescent or stained with fluorescent dyes. Fluorescence microscopy uses bright-field microscopy technology. When the UV light source is activated, the fluorescent portion of the specimen glows against a light background. Fluorescence microscopy uses lasers.

Specimens that are examined using fluorescence microscopy may be naturally fluorescent or stained with fluorescent dyes. Fluorescence microscopy uses bright-field microscopy technology. Fluorescence microscopy uses lasers.

As resolution ______ the clarity of the image ______. a.increases; increases b.decreases; decreases c.decreases; increases d.decreases; stays the same e.increases; stays the same

a

Light is ______ when it passes from one medium to another with a different optical density. a.refracted b.resolved c.magnified d.focused e.Both b and d are correct.

a

Scanning tunneling microscopy and atomic force microscopy are fundamentally different from other types of microscopy because they ______. a.use a nanoprobe that scans the surface of the specimen to produce an image b.use a scattered electron beam to produce an image c.assemble an image from light defracted off the surface of the specimen by prisms d.only work on living specimens e.Both b and d are correct.

a

All of the following are stains attracted to a bacterial cell wall EXCEPT (Select all that apply) alcohol crystal violet Gram's iodine safranin

alcohol Gram's iodine

The three-dimensional aspect of the Stentor image is created by ______. a.the use of dyes b.changes in the phases of light as it passes through the specimen c.coating of the specimen with metals d.the type of glass in the eyepiece of the microscope e.the large size of the specimen

b

Which microscope generates a three-dimensional image and converts differences in refractive indexes in a specimen to differences in color as the result of using prisms? a.phase contrast microscope b.differential interference contrast microscope c.confocal microscope d.dark-field microscope e.Both a and c are correct.

b

A fluorescent dye absorbs the energy from ______ and emits light in the visible spectrum. a.an electron beam b.another fluorescent dye c.ultraviolet light d.phalloidin e.fluorescein

c

A transmission electron microscope uses ______ for lenses and a(n) ______ to form the image. a.electromagnets; nanoprobe b.glass; nanoprobe c.electromagnets; electron beam d.glass; electron beam e.electron beams; electromagnets

c

Image size divided by actual size is a measure of ______. a.resolution b.refractive index c.magnification d.numerical aperture e.focal length

c

In which type of microscope does the specimen appear against a black background because of light being reflected off the surface of the specimen into the objective lens? a.differential interference microscope b.confocal microscope c.dark-field microscope d.super-resolution microscope e.bright-field microscope

c

Staining procedures that use multiple dyes are called ______. a.simple staining b.negative staining c.differential staining d.acidic staining e.mordant staining

c

Which of the following is a stain? (Select all that apply) crystal voilet carbol fuchsin Gram's iodine safranin

crystal voilet carbol fuchsin safranin

A positive test for a pathogen produced by a(n) ______ dye conjugated to a ______ shows as glowing spots when viewed with a(n) ______ microscope. a.acid; fluorescent antibody; dark-field b.basic; polyclonal antibody; bright-field c.neutral; fluorescent antibody; confocal d.fluorescent; monoclonal antibody; fluorescence e.acid; monoclonal antibody; electron

d

If a light microscope has a 10× ocular lens and a 40× objective lens, how large will the image of an amoeba 15 μm in diameter appear? a.150 μm b.600 μm c.1.5 mm d.6.0 mm e.750 μm

d

Place the listed chemicals in the correct order for Gram staining: safranin, iodine, ethanol, crystal violet a.crystal violet, safranin, ethanol, iodine b.iodine, safranin, ethanol, crystal violet c.iodine, crystal violet, safranin, ethanol d.crystal violet, iodine, ethanol, safranin e.crystal violet, iodine, safranin, ethanol

d

With a compound microscope, light intensity is controlled by adjusting the ______. a.condenser lens b.focus knob c.stage d.iris diaphragm e.ocular lens

d

STMs and AFMs produces images with _______________ that move over the surface of the specimen. diamond-tipped or metal-tipped probes electron beams magnets photons

diamond-tipped or metal-tipped probes

A(n) ______ microscope is a variation of a fluorescence microscope that uses point illumination and scanning to produce a three-dimensional image. a.scanning electron b.scanning tunneling c.atomic force d.differential interference contrast e.confocal

e

Tuberculosis is caused by Mycobacterium tuberculosis, a(n) ______ bacterium. a.non-acid-fast b.gram-positive c.gram-variable d.gram-negative e.acid-fast

e

All of the following characteristics apply to a TEM EXCEPT electrons are scattered off the surface of the specimen. the electron beam passes through a very thin specimen section. sample preparation is both expensive and extensive. some specimens undergo staining with harsh chemicals or cryofixation.

electrons are scattered off the surface of the specimen.

The application of two distinctly different stains is used with bacteria that have (Select all that apply) only one flagellum endospores. at least one flagella. a polysaccharide coating.

endospores. a polysaccharide coating.

All of the following are steps involved in making a smear EXCEPT applying a bacterial call suspension to a microscopic slide. air drying the slide with the bacterial cell suspension smeared over it. fixing the bacteria to the slide using 95% phenol. spreading of a bacterial cell suspension over the surface of a slide using a sterile inoculating loop.

fixing the bacteria to the slide using 95% phenol.

Organisms that are known to be peritrichous could be visualized using a/an endospore stain. capsule stain. flagella stain. negative stain.

flagella stain.

During Gram staining, the alcohol acts on membrane lipids. integral proteins. carbohydrates. peripheral proteins.

membrane lipids.

is defined as the clarity of an image.

resolution

Select the CORRECT pairing. scanning electron microscopy : electron beam scans specimen surface to produce 3-D image of specimen phase contrast microscopy : assembles scanned region into different focal planes differential interference contrast microscopy : two closely spaced fluorescent sources are imaged separately super resolution microscopy : electron beam is passed through specimen and focused by Electromagnet lenses

scanning electron microscopy : electron beam scans specimen surface to produce 3-D image of specimen

From the following choices, which would increase the resolution of an image the most? indigo light green light violet light orange light

violet light