Deck 4: Microscopy, Staining, and Classification

Question 1

Heat is used to drive the stain into cells in the staining procedure(s).

A) endospore stain
B) capsule stain
C) Gram stain
D) acid-fast stain
E) both acid-fast and endospore stains

Answer 1

E

Question 2

Which of the following are magnifying lenses?

A) dark-field stops
B) objectives
C) oculars
D) condensers
E) both objectives and the oculars

Answer 2

E

Question 3

A sample is prepared using osmium tetroxide as a stain. This sample has been prepared for a(n) microscope.

A) phase-contrast
B) fluorescence
C) atomic force
D) differential interference contrast
E) electron

Answer 3

E

Question 4

If a microbiology lab student left the safranin out of the Gram stain procedure, what would be the result?

A) All cells would be pink.
B) Gram-positive cells would be purple and Gram-negative cells would be colorless.
C) Gram-positive cells would be colorless and Gram-negative cells would be pink.
D) All cells would be purple.
E) Gram-positive cells would be pink and Gram-negative cells would be purple.

Question 5

Which of the following microscopes produces the highest resolution images?

A) differential interference
B) fluorescent
C) dark-field
D) scanning electron
E) atomic force

Question 6

The acid-fast stain is used to stain

A) bacteria with waxy cell walls.
B) endospores.
C) bacteria lacking cell walls.
D) living bacteria.
E) bacteria with capsules.

Question 7

Species and strains of microbes can be distinguished from one another phenotypically using

A) Gram-stain reactions.
B) electron microscopy.
C) ribosomal RNA analysis.
D) serological tests.
E) G + C content.

Question 8

High resolution images of the internal structures of microbial cells are obtained using microscopes.

A) atomic force
B) confocal
C) transmission electron
D) scanning tunneling
E) scanning electron

Question 9

The light source in a microscope is ultraviolet (UV) light.

A) fluorescent
B) phase-contrast
C) Nomarski
D) bright-field
E) dark-field

Question 10

Unstained cells that lack pigment are best observed on the microscope.

A) scanning electron
B) bright-field
C) scanning tunneling
D) phase-contrast
E) transmission electron

Question 11

Why does immersion oil improve resolution?

A) It increases the angle of refraction of the light.
B) It allows light to travel at a uniform speed on its way to the lens.
C) It decreases the working distance.
D) It increases the numerical aperture.
E) It increases numerical aperture and maintains a uniform light speed.

Question 12

You are shown a micrograph from a light microscope in which the specimens appear bright compared to the background. The micrograph is probably from a(n) microscope.

A) dark-field
B) Nomarski
C) bright-field
D) atomic force
E) phase-contrast

Question 13

A useful unit for measuring the size of most cells is

A) nanometers.
B) micrometers.
C) decimeters.
D) millimeters.
E) centimeters.

Question 14

Safranin dye is used as the counterstain in stain(s).

A) the endospore
B) the acid-fast
C) the flagellar
D) the Gram
E) both the Gram and the endospore

Question 15

The ability of a lens to gather light is referred to as its

A) numerical aperture.
B) magnification.
C) contrast.
D) resolution.
E) refraction.

Question 16

The rules of naming organisms are called

A) taxonomy.
B) classification.
C) identification.
D) nomenclature.
E) binomials.

Question 17

Which of the following is an INCORRECT pairing?

A) magnification; refraction of radiation
B) electron beams; shorter wavelength
C) contrast; staining techniques
D) dark field:high contrast
E) numerical aperture; curved glass

Question 18

The kingdoms included in the Linnaeus system of classification are

A) Animalia and Plantae.
B) Fungi and Protista.
C) Prokaryotae and Protista.
D) Protista and Plantae.
E) Animalia and Prokaryotae.

Question 19

All of the following are common to both the Gram stain and the acid -fast stain EXCEPT

A) primary stain.
B) a chemical mordant.
C) counterstain.
D) a decolorizing agent.
E) a decolorizing agent and a counterstain.

Question 20

Lasers are used to generate the images produced by microscopes.

A) fluorescent
B) atomic force
C) confocal
D) phase-contrast
E) both confocal and atomic force

Question 21

Why have some microbiologists proposed using ribosomal RNA as the basis for defining bacterial species?

A) Bacteria are not interbreeding populations, and ribosomal RNAs are highly conserved genes present in all prokaryotes.
B) Ribosomal RNAs are highly conserved genetic sequences present in all prokaryotes.
C) Bacteria vary too little in their physical and biochemical traits.
D) The ʺinterbreeding populationʺ criterion does not apply to bacteria.
E) Ribosomal RNA is the basis for domain assignment.

Question 22

Which of the following classification methods relies on the morphology of organisms?

A) biochemical tests
B) physical (phenotypic) characteristics
C) analysis of nucleic acids
D) serological tests
E) phage typing

Question 23

Carl Woese proposed the concept of the domain based on differences of which of the following cellular molecules?

A) DNA
B) ribosomal RNA
C) proteins
D) membrane lipids
E) transfer RNA

Question 24

A virologist wants to observe the surface features of virus particles she is studying. Which of the following microscopes would NOT be useful for her observations?

A) transmission electron
B) scanning electron
C) atomic force
D) scanning tunneling
E) differential interference contrast

Question 25

The light path illustrated in the figure represents a microscope.

A) phase contrast
B) dark-field
C) bright-field
D) fluorescence
E) differential interference contrast

Question 26

A new single-celled organism is discovered living in an ant colony. Which of the following classification methods would be appropriate for identifying to which domain it belongs?

A) physical characteristics
B) biochemical tests
C) phage typing
D) analysis of nucleic acids
E) serological tests

Question 27

In the Gram stain procedure, iodine serves as a

A) fixative.
B) mordant.
C) decolorizing agent.
D) counterstain.
E) primary stain.

Question 28

Why are modern light microscopes better than the ones Leeuwenhoek used?

A) Modern microscopes have a fivefold better resolution.
B) Modern microscopes have lenses with smaller numerical apertures.
C) Modern lenses are made of prisms.
D) Modern microscopes are compound and have fivefold better resolution.
E) Modern microscopes are compound instead of simple.

Question 29

A structure that appears in a transmission electron micrograph but is NOT actually present in the specimen is known as a(n)

A) biofilm.
B) artifact.
C) antigen.
D) refraction.
E) mordant.

Question 30

The Gram stain works because of differences in the of bacteria.

A) cell membranes
B) genetic characteristics
C) antigens
D) cell walls
E) capsules

Question 31

Tungsten is a reagent used in the

A) flagellar stain.
B) negative stain.
C) endospore stain.
D) electron microscopy stain.
E) acid-fast stain.

Question 32

A sample from a patient is prepared using the Gomori methenamine silver stain. What type of microbe is suspected of being present?

A) bacteria
B) parasitic worm larva
C) virus
D) protozoal parasite
E) fungus

Question 33

Which of the following statements is CORRECT regarding modern taxonomy?

A) There is consensus about the definition of species.
B) Modern classifications reflect evolutionary relationships of organisms.
C) Modern taxonomy does not provide a basis for predicting structural relationships.
D) The modern taxonomic organization is a finished product.
E) It is a complete inventory of all living organisms.

Question 34

Which of the following is the correct order, from largest to smallest, of the modern taxonomic hierarchy?

A) Phylum, Kingdom, Class, Domain, Order, Family, Genus, Species
B) Kingdom, Domain, Class, Phylum, Family, Order, Species, Genus
C) Class, Domain, Family, Genus, Kingdom, Order, Phylum, Species
D) Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
E) Kingdom, Family, Class, Phylum, Order, Genus, Species

Question 35

Which of the following statements is CORRECT about scanning electron microscopes?

A) Thin segments must be used.
B) The sample is placed in a vacuum.
C) Stains can be applied to improve contrast.
D) Images of surface structures are produced.
E) Glass lenses are used.

Question 36

A thin film of microbes on a slide is

A) fixation.
B) a smear.
C) agglutination.
D) a biopsy.
E) a Gram reaction.

Question 37

Which of the following phenomena produces magnification?

A) the thickness of a microscopic specimen
B) the refraction of radiation as it passes through a lens
C) the numerical aperture of a lens
D) the length of an objective lens
E) the wavelength of a radiation source

Question 38

Viruses are NOT included in the taxonomic scheme proposed by Carl Woese because they lack

A) proteins.
B) lipid membranes.
C) cytoplasm.
D) genetic material.
E) ribosomal RNA.

Question 39

In Gram staining, ethanol-acetone is used as a

A) primary stain.
B) decolorizing agent.
C) mordant.
D) counterstain.
E) drying agent.

Question 40

Acidic dyes

A) are used for staining negatively charged molecular structures.
B) are negatively charged and work best at low pH.
C) are lipid soluble.
D) are negatively charged.
E) work best in low-pH environments.

Question 41

The limits of resolution of atomic force microscopes is in the range of

A) meters (m).
B) nanometers (nm).
C) centimeters (cm).
D) millimeters (mm).
E) micrometers (μm).

Question 42

Methylene blue can be used to stain DNA because it

A) covalently bonds with DNA.
B) makes DNA electron dense.
C) forms ionic bonds with DNA.
D) changes the pH and therefore the structure of DNA.
E) is an effective fixing agent for nucleic acids.

Question 43

Bacteria and many other microbes do NOT and therefore do NOT fit Linnaeusʹ definition of species.

A) exchange genetic material
B) reproduce sexually
C) reproduce asexually
D) have nuclei
E) have cytoplasmic membranes

Question 44

Light rays that are in phase reinforce each other and produce a brighter image.

Question 45

A resolution of 1μm would be better than a resolution of 0.5 μm.

Question 46

Three-dimensional images of specimens can be obtained using scanning electron microscopes.

Question 47

The endospore stain reveals internal structures within cells of the genera Bacillus and Clostridium.

Question 48

The most appropriate unit of measurement for intact archaea is the

A) nanometer (nm).
B) micrometer (μm).
C) millimeter (mm).
D) meter (m).
E) centimeter (cm).

Question 49

The stain is one in which eosin is used.

A) flagellar
B) electron microscopy
C) negative
D) endospore
E) acid-fast

Question 50

Scanning tunneling microscopes map the topography of a specimen by detecting the deflection of the probe tip.

Question 51

Light rays that pass through the edge of a curved lens will be refracted more than those that pass through the center.

Question 52

The three domains proposed by Carl Woese are the Archaea, the Eukarya, and the Protista.

Question 53

Stains for light microscopy contain chromophores whereas stains for electron microscopy contain heavy metals.

Question 54

Tannic acid is a mordant (chemical fixative) used in the stain.

A) acid-fast
B) flagellar
C) endospore
D) negative
E) electron microscopy

Question 55

Gram staining of bacteria provides all the physical characterization necessary to identify bacterial species.

Question 56

Acid-fast cells such as Mycobacterium lose the color of the primary stain in the presence of hydrochloric acid.

Question 57

The part(s) of the microscope indicated by the arrows is/are the

A) oculars.
B) condenser lens.
C) objectives.
D) body.
E) diaphragm.

Question 58

This image was most likely produced by a microscope.

A) scanning electron
B) bright-field
C) confocal
D) transmission electron
E) dark-field

Question 59

A measurement of a microbe is reported as 1 × 10-6 m, also known as

A) micrometers (μm).
B) yards.
C) nanometers (nm).
D) millimeters (mm).
E) centimeters (cm).

Question 60

One-thousandth of a meter is a

A) micrometer (μm).
B) yard.
C) millimeter (mm).
D) centimeter (cm).
E) nanometer (nm).

Question 61

Compare and contrast the light microscope with the electron microscope.

Question 62

The agglutination test uses proteins called (antibodies/antigens/chromophores) to detect species-specific features of microbes.

Question 63

You are a scientist studying the highly specific interactions of bacteriophages with their host cells when they first encounter the cell. Discuss what microscope(s) and preparation procedures you might use for this study.

Question 64

The total magnification using a 10 ocular and a 100 objective would be (110/1000/10000) X.

Question 65

A primary purpose for the use of stains in microscopy is the increase the (magnification/brightness/contrast) of a specimen.

Question 66

Bacterial viruses, called (bacteriophages/serotypes/bacteriotypes), can be used to help classify different groups of bacteria.

Question 67

Compare and contrast the three domains identified by Woese: Eukarya, Bacteria, and Archaea.

Question 68

The process of immobilizing organisms on a glass slide through the application of either heat or chemicals is (staining/mordant/fixation).

Question 69

Staining procedures called (background/negative/positive/contrasting) provide increased contrast by staining the background.

Question 70

Discuss the ways in which light rays can be manipulated to increase resolution and/or contrast.

Question 71

List and explain five types of techniques that can be used to identify unknown microorganisms.

Question 72

Figure 4-4 represents a (dichotomous/taxonomic/question) key of the type used to identify a microbe.

Question 73

Carl Woese and his colleagues proposed the (phylum/domain/family), a taxon that contains multiple kingdoms.

Question 74

The system of taxonomy used today was originated by (Linnaeus/Darwin/Woese).

Question 75

A(n) (acidic/metallic/fluorescent) molecule is one that absorbs invisible radiation and emits visible light.

Question 76

An integral part of serological testing is the use of a solution called (blood/plasma/antiserum) that contains antibodies.

Question 77

The technique called (confocal/electron/probe) microscopy uses detection of deflection to map surfaces of molecular structures.

Question 78

Coating a specimen with a heavy metal is a step in preparing it for (phase/fluorescent/electron) microscopy.

Question 79

In a compound microscope, the lens that directs light through the specimen is the (ocular/condenser/objective) lens.

Question 80

A (bright-field/confocal/phase-contrast) light microscope can be used to generate three-dimensional images.