Chapter 3 Reading Questions

What is the numerical aperture range?

0.1 in the lowest-power lens to approximately 1.25 in the highest-power (oil immersion) lens

A fluorescent microscope uses which of the following to view a specimen? An atomic probe Visible light An electron beam Ultraviolet light

Ultraviolet light

The color-bearing portion of a dye is termed the ________ and has a charge that attracts it to certain cell parts bearing the opposite charge.

chromophore

The condenser converges (focuses) light to a single point on the specimen in a ________ microscope.

compound

A scanning _________ microscope uses a laser beam of light to scan various depths in a specimen.

confocal

The _______ _________ contrast microscope produces well-defined images that are vividly colored and appear three-dimensional.

differential interference

____________ staining is designed to distinguish between spores stained with malachite green and the vegetative cells from which they are produced.

endospore or spore

Different types of culture _________ provide nutrients for microbial growth

media

The _______ _______ is a mathematical constant derived from the physical structure of the lens of a microscope.

numerical aperture

The _______ _________ is the mathematical constant that describes the relative efficiency of a lens in bending light rays.

numerical aperture

The resolving power of a microscope is calculated by dividing the wavelength of light by double the _______ of the objective lens. magnification power numerical aperture length refraction

numerical aperture

Microscopes are equipped with a nosepiece holding three ________ lenses which vary in magnification.

objective

_______ - ________ are reliant on varying densities in the structure of a microorganism which allows us to see the specimen.

phase-contrast

_______ stains require only a single dye.

Simple

The numerical aperture in the oil immersion lens is approximately which of the following? 1.25 0.50 0.75 1.00

1.25

The numerical aperture in the oil immersion lens is approximately which of the following? 1.25 1.00 0.75 0.50

1.25

Light and electron microscopes magnify the specimen in stages by how many lens systems? 5 3 1 2 4

2

Magnification of an object or specimen by a compound microscope occurs in how many phases? 2 5 3 1 4

2

Which of the following staining procedures is used to detect Mycobacterium tuberculosis? Endospore stain Gram stain Negative stain Acid-fast stain

Acid-fast stain

To be effective, a microscope must have which of the following characteristics? UV fluorescence capabilities Adequate magnification Clarity of image Resolution

Adequate magnification, clarity of image, and resolution

What is involved in making a smear? Air drying a liquid application on a glass slide Applying a liquid suspension to a cover slip Spreading a thin film of suspended cells on a glass slide Staining the slide background and then applying cells

Air drying a liquid application on a glass slide Spreading a thin film of suspended cells on a glass slide

Which of the following pairs are correct? Cationic dyes = Acidic dyes Anionic dyes = Acidic dyes Cationic dyes = Basic dyes Anionic dyes = Basic dyes

Anionic dyes = Acidic dyes Cationic dyes = Basic dyes

Which immunological compounds can be used in conjunction with fluorescent dyes to better visualize microorganisms? Antibodies Complement proteins Neutrophils T cells

Antibodies

Which of the following genera are capable of producing endospores? Streptococcus Staphylococcus Escherichia Bacillus Clostridium

Bacillus Clostridium

I am attempting to stain a bacterium that has a negatively charged cell surface. Which dye should I use?

Basic

Why is the use of immersion oil sometimes necessary when using a microscope? Because oil keeps the specimen wet Because oil evaporates slower than water Because oil doesn't dissolve the specimen Because oil has the same refraction as glass and lens

Because oil has the same refraction as glass and lens

Which of the following wavelengths should give the best resolution? Red Yellow Green Blue

Blue

Which type of microscope forms its image when light is transmitted through a specimen? Bright-field microscope Phase-contrast microscope Dark-field microscope

Bright-field microscope

Identify the four types of visible-light microscopes. Bright-field Phase-contrast Scanning tunneling Atomic force Dark-field Confocal Interference

Bright-field, dark-field, phase-contrast, and interference

How does a transmission electron microscope produce its image? By transmitting a laser beam through the specimen By transmitting light through the specimen By transmitting electrons through the specimen

By transmitting electrons through the specimen

Identify the benefits of using a hanging drop mount. Can assess shape Can assess cellular arrangement Can assess size Can assess motility Can assess whether Gram-negative or positive

Can assess shape Can assess cellular arrangement Can assess size Can assess motility

How much resolution can an electron microscope obtain (i.e. what can it see)? Can see structures as small as 100 nm Can see structures as small as 0.5 nm Can see structures as small as 0.5 mm Dark-field microscopes can magnify better.

Can see structures as small as 0.5 nm

_______ staining is designed to observe the unstructured protective layer surrounding some bacteria and fungi.

Capsule, Negative, or Capsular

Negative staining of a cell can yield results concerning which of the following? Cell size The presence of a capsule The presence of flagella The type of cell wall Cell shape and arrangement

Cell size The presence of a capsule Cell shape and arrangement

________ are large masses or mounds of cells, all belonging to a single type of microorganism.

Colonies

Which of the following is a macroscopic discrete cluster of cells that forms on a solid nutrient surface arising from the multiplication of a single cell? Culture Inoculum Colony Growth

Colony

Which term is used to describe a cluster of visible bacteria of the same species on an agar plate? Mold Colony Lawn Plaque

Colony

Which of the following is the typical "color" of microorganisms? Red Colorless Purple Green Blue

Colorless

Which of the following is the defining difference between compound microscopes and simple microscopes? Compound microscopes have two stage adjustment knobs. Compound microscopes have multiple lenses. Compound microscopes have an iris diaphragm. Compound microscopes have an "arm".

Compound microscopes have multiple lenses

Which of the following microscope components is used to converge (or focus) the rays of light to a single point on the specimen? Condenser Stage Coarse adjustment knob Iris diaphragm Lamp

Condenser

Which of the following microscopes uses a laser beam? Confocal Interference Bright-field Fluorescence

Confocal

Through different staining techniques it is possible to increase the ________________ on the slide making it easier to view details of the specimen.

Contrast - The primary purpose of staining is to increase CONTRAST!

Which of the following terms is used to describe a collection of bacteria growing in broth or on agar? Growth Fastidious Culture Colony

Culture

Which microscope uses standard light which is directed only at the sides of the specimen? Phase contrast Dark-field Electron tunneling Bright-field

Dark-field

Which of the following microscopes provide detailed views of unstained, live specimens? Bright-light microscope Differential interference microscope Phase-contrast microscope Dark-field microscope Confocal microscope

Differential interference microscope and dark-field microscope

Which of the following microscopes uses subatomic particles, not light waves, as an illumination source to provide high magnification and high resolution? Confocal Dark-field Fluorescence Differential interference Electron

Electron

Which of the following has the greatest magnification power? Dark-field microscope They are all the same! Light microscope Electron microscope Fluorescent microscope

Electron microscope

Capsule staining is used to observe the unstructured protective layer surrounding some of which groups of microorganisms? Fungi Viruses Bacteria Helminths

Fungi and bacteria

T/F: A wet, hanging drop mount can assess whether an organism is Gram-negative or positive.

False

T/F: Light-based microscopes can obtain greater magnification than electron microscopes.

False

T/F: True or false: All specimens are prepared in the same manner for microscopic examination.

False

Which staining is based on the dying of external cell structures used for locomotion in order to enlarge them and make them visible? Capsular Flagellar Negative Gram

Flagellar

________ staining is a method of revealing flagella.

Flagellar or Flagellum

Which of the following methods would be preferred to visualize a microorganism for a true assessment of size, shape, color, and motility? Basic stain Hanging drop method Gram stain

Hanging drop method

Which of the following is a common method for attaching bacteria to a glass slide? Alcohol fixation Formalin denaturation Heat fixation

Heat fixation

How is the endospore stain similar to the acid-fast stain? Both stain the endospore. Heat is applied to force the dye in. A mordant is used to set the dye. Acid alcohol is used to wash the dye out of the cell.

Heat is applied to force the dye in.

Identify which of the following could potentially affect the manner in which a specimen is prepared for microscopic examination. If the specimen is living or preserved If you want to use fluorescence microscopy If you are in a hurry If you want to observe motility If you want to see the overall structure or something specific

If the specimen is living or preserved If you want to use fluorescence microscopy If you want to observe motility If you want to see the overall structure or something specific

What can be used to enhance the amount of light passing through the specimen and the many lenses to reach the eye? Safranin Water Immersion oil Crystal violet Decrease the temperature

Immersion oil

Identify a dye that results in a negative stain. Alcohol India ink Eosin Cyanosin

India ink

Which can be used to produce a negative stain? India ink Nigrosin Crystal violet Safranin Iodine

India ink and nigrosin

Which term identifies the introduction of microorganisms into an environment in which they will multiply? Incubation Inoculation Inspection Identification Seeding

Inoculation

Which of the following six "I'"s deals with the evaluation of cultures both macroscopically and microscopically? Isolation Inoculation Inspection Incubation Identification

Inspection

Which of the following are part of the six basic techniques used to grow, examine and manipulate microorganisms in the laboratory? Inspection Infection Interrogation Isolation Inoculation

Inspection, isolation, and inoculation

Which describes any technique that results in individual bacteria separate from others? Isolation Infection Inoculation Incubation

Isolation

A scanning confocal microscope is characterized by which of the following? Its use of a beam of electrons to scan the specimen Its use of ultraviolet radiation to scan the specimen Its use of a laser beam to scan the specimen

Its use of a laser beam to scan the specimen

Which of the following describes how dark-field microscopy works? Light is focused into the specimen from the sides. Blue light is used. Light comes from the top down rather than bottom up. UV light is used.

Light is focused into the specimen from the sides.

Magnification results from the interaction of which of the following? Optical aperture and light source Lens curvature and optical aperture Light waves and lens curvature

Light waves and lens curvature

A wet mount is suitable for observing which of the following? Living, motile or non-motile cells Dry, motile or non-motile cells Stained, motile or non-motile cells

Living, motile or non-motile cells

Which of the following identifies the method that requires you to serially dilute microorganisms by passing them from one tube of cool but still liquid agar to another, and then eventually pouring them into petri plates with the intended purpose of obtaining individual colonies? Loop dilution method Streak plate method Spread plate method

Loop dilation method

Which of the following is a vital characteristic of a reliable microscope? A UV light source Magnification Image software

Magnification

Identify the simple stain(s). Malachite green Methylene blue Crystal violet Gram stain

Malachite green Methylene blue Crystal violet

__________ staining is a general type of staining that does not disrupt the cell structure with heat fixation and can indicate the presence of a capsule.

Negative

Which of the following staining procedures produces a reverse image of that created by a positive stain, thus forming a silhouette around the microorganism's outer boundary? Negative stain Simple stain Differential stain Gram stain

Negative stain

Which of the following are applications of bright-field microscopy? Observation of dark specimens in a white field Observation of fluorescent samples Observation of the internal structure of viral particles Observation of live and preserved stained specimens

Observation of dark specimens in a white field and observation of live and preserved stained specimens

Organelles, granules, and bacterial endospores are best observed using which microscope? Phase-contrast Scanning-electron Dark-field Bright-field

Phase-contrast

When Nocardia is stained with the acid-fast stain, the microbes exhibit what color? Blue Violet Green Pink

Pink

Which of the following represent inoculation of a microbial sample? Sequencing of the microbial DNA Placing a sample in sterile medium Examining a microbe under the microscope Maintaining a sample at body temperature Streaking a sample on an agar plate

Placing a sample in sterile medium Streaking a sample on an agar plate

_______ staining involves any staining technique in which the dye actually sticks to the specimen and gives it color.

Positive

Heat fixing a sample in microscopy is done for which purpose? Preserving various cellular components in a natural state Drying the liquid used to make the smear Making a more permanent mount for long-term study Highlighting cell structure for observation Simultaneously killing and securing the sample to the slide

Preserving various cellular components in a natural state Making a more permanent mount for long-term study Simultaneously killing and securing the sample to the slide

Gram positive bacteria exhibit with color after the Gram-stain? Green Blue Pink Purple

Purple

Which of the following is the initial image of a specimen formed by the objective lens? Real image Virtual image Fixed image

Real image

_______ power is the ability of a microscope to show detail.

Resolving

Which is the factor that most limits the clarity of a microscope's image? Resolving power Oil immersion objective Light source Magnification

Resolving power

Which of the following wavelengths should give the best resolution? Short wavelengths Ultra long wavelengths Long wavelengths

Short wavelengths

Identify disadvantages of wet mount preparations. Living cells cannot be visualized with wet mounts. Slide very susceptible to drying Dyes easily transferred to handler's fingers. Easy contamination of handler's fingers Damage to large cells by cover glass

Slide very susceptible to drying Easy contamination of handler's fingers Damage to large cells by cover glass

A collection of bacteria on a loop which is thinly spread across a glass slide, allowed to air-dry, and heat fixed is called a _______

Smear

Which of the following is unique to dark-field microscopes? Stop-condenser Nosepiece Coarse adjustment knob Ocular lens Objective lens

Stop-condenser

Identify the method of spreading a small culture sample over a solid medium in a pattern that gradually thins out the sample resulting in isolated colonies. Streak plate method Loop dilution/pour plate method Spread plate method Inoculation plate method

Streak plate method

The type of mount in which a specimen is prepared for optical microscopy is dependent upon which of the following? Whether the microbe is pathogenic or not The condition of the specimen The type of microscopy available The number of microbes present The aims of the examiner

The condition of the specimen The type of microscopy available The aims of the examiner

How does the loop dilution/pour plate technique result in colony isolation? Spread on the surface The sample is partially killed by the melted agar. The sample is serially diluted before dispensing into petri dishes. Introduced by a needle allowing isolated subsurface growth

The sample is serially diluted before dispensing into petri dishes.

Which of the following is defined as the magnification of the ocular lens times the magnification of the objective lens? Resolution Index of refraction Total magnification Resolving power

Total magnification

What is the method of choice to view detailed structural characteristics of both cells and viruses? Phase-contrast microscopy Fluorescence microscopy Transmission electron microscopy

Transmission electron microscopy

T/F: Acidic dyes tend to bind to alkaline structures.

True

True or false: The specimen used in SEM is metal-coated before it is bombarded with electrons.

True

What term is used to describe the image generated by the ocular lenses of a microscope? Real image Actual image Virtual image

Virtual image

Which of the following is the terminology used to describe the image of something viewed using a microscope? Real image Fixed image Actual image Virtual image

Virtual image

__________ technique is the set of procedures used in the laboratory to prevent the contamination of cultures with unwanted microbes and infection of the technician.

aseptic

________ dyes have a positive charge, whereas _______ dyes have a negative charge.

basic, acidic

________ - __________ microscopy is most effectively used to visualize living cells that would be distorted by drying or heat.

dark-field

The ________ stain is the most universal differential staining technique for bacteria, and it differentiates bacteria based on their cell wall structure.

gram

Basic dyes carry a _________ charged chromophore and acidic dyes have a ________ charged chromophore.

positively, negatively

_____ ______ or resolution defines the capacity of an optical system to distinguish tow adjacent objects or points from one another.

resolving power

The Gram stain uses a red dye known as ________, whereas the acid-fast stain uses carbol fuschin.

safranin

The first microscopes were _______ meaning they contained just one magnifying lens and few working parts.

simple

The ______ image of a microscopic specimen is the one that will be received by the eye and converted to a retinal and visual image.

virtual