Question 1

The acid-fast stain is specifically designed for bacteria whose cell walls contain:

Accepted Answer

A)  teichoic acids. 
B)  mycolic acids. 
C)  peptidoglycan. 
D)  disaccharide-pentapeptide subunits. 
A)  teichoic acids. 
B)  mycolic acids. 
C)  peptidoglycan. 
D)  disaccharide-pentapeptide subunits. B

Question 2

Bacterial cells with thick peptidoglycan and numerous teichoic acid cross-linkages are Gram stained.The organisms stain pink.Which one of the following statements explains this discrepancy?

Accepted Answer

A)  The bacterial cells were most likely not heat-fixed to the slide. 
B)  The bacterial cells were subjected to the decolorizer too long and were overdecolorized. 
C)  The lot of Gram-stain reagent is most likely expired. 
D)  No discrepancy exists; cells with this composition stain pink on Gram stain. 
A)  The bacterial cells were most likely not heat-fixed to the slide. 
B)  The bacterial cells were subjected to the decolorizer too long and were overdecolorized. 
C)  The lot of Gram-stain reagent is most likely expired. 
D)  No discrepancy exists; cells with this composition stain pink on Gram stain. B

Question 3

The fluorochrome stain that can be used to detect mycobacteria is:

Accepted Answer

A)  calcofluor white. 
B)  acridine orange. 
C)  auramine. 
D)  immunofluorescence. 
A)  calcofluor white. 
B)  acridine orange. 
C)  auramine. 
D)  immunofluorescence. C

Question 4

An organism such as Mycobacterium tuberculosis would absorb which stain in its cell wall?

Accepted Answer

A)  Crystal violet 
B)  Methylene blue 
C)  Carbolfuchsin 
D)  Malachite green 
A)  Crystal violet 
B)  Methylene blue 
C)  Carbolfuchsin 
D)  Malachite green

Question 5

Of the different types of staining and microscopic techniques, which one of the following is basically the most sensitive?

Accepted Answer

A)  Chromogenic 
B)  Fluorescence 
C)  Phase contrast 
D)  Light field 
A)  Chromogenic 
B)  Fluorescence 
C)  Phase contrast 
D)  Light field

Question 6

Magnifications in excess of 100,000 ´ are achieved by ________ microscopy?

Accepted Answer

A)  bright-field 
B)  electron 
C)  dark-field 
D)  phase-contrast 
A)  bright-field 
B)  electron 
C)  dark-field 
D)  phase-contrast

Question 7

A mordant that is applied after the primary stain to bond chemically the alkaline dye to the bacterial cell wall is:

Accepted Answer

A)  safranin. 
B)  crystal violet. 
C)  Gram's iodine. 
D)  Gram's decolorizer. 
A)  safranin. 
B)  crystal violet. 
C)  Gram's iodine. 
D)  Gram's decolorizer.

Question 8

Which of the following statements is true concerning dark-field microscopy?

Accepted Answer

A)  This type of microscopy uses specific stains to enhance the contrast of certain bacteria. 
B)  The condenser does not allow light to pass directly through the specimen but directs the light to hit the specimen at an oblique angle. 
C)  Dark-field microscopy allows the visualization of larger viruses. 
D)  Dark-field microscopy can differentiate various difficult-to-grow organisms by using immunofluorescence. 
A)  This type of microscopy uses specific stains to enhance the contrast of certain bacteria. 
B)  The condenser does not allow light to pass directly through the specimen but directs the light to hit the specimen at an oblique angle. 
C)  Dark-field microscopy allows the visualization of larger viruses. 
D)  Dark-field microscopy can differentiate various difficult-to-grow organisms by using immunofluorescence.

Question 9

After which step in the Gram-stain procedure are gram-positive bacteria first distinguished from gram-negative bacteria?

Accepted Answer

A)  Crystal violet 
B)  Iodine mordant 
C)  Gram's decolorizer 
D)  Safranin 
A)  Crystal violet 
B)  Iodine mordant 
C)  Gram's decolorizer 
D)  Safranin

Question 10

In microscopy, resolution can be defined as the:

Accepted Answer

A)  magnification power. 
B)  extent to which detail in the magnified object is maintained. 
C)  ability of objects to stand out from the background. 
D)  ability to see objects against a black background. 
A)  magnification power. 
B)  extent to which detail in the magnified object is maintained. 
C)  ability of objects to stand out from the background. 
D)  ability to see objects against a black background.

Question 11

The fluorochrome stain used to study a fungus is:

Accepted Answer

A)  calcofluor white. 
B)  acridine orange. 
C)  auramine. 
D)  immunofluorescence. 
A)  calcofluor white. 
B)  acridine orange. 
C)  auramine. 
D)  immunofluorescence.

Question 12

In the Kinyoun acid-fast staining method, ______ replaces _____ in the primary stain solution.

Accepted Answer

A)  increased phenol; heat 
B)  heat; increased phenol 
C)  mycolic acid; heat 
D)  carbolfuchsin; phenol 
A)  increased phenol; heat 
B)  heat; increased phenol 
C)  mycolic acid; heat 
D)  carbolfuchsin; phenol

Question 13

Contrast in microscopy is most commonly achieved by:

Accepted Answer

A)  changing objectives for various specimens. 
B)  increasing the resolution or resolving power. 
C)  staining techniques. 
D)  adding a blue filter to the light path. 
A)  changing objectives for various specimens. 
B)  increasing the resolution or resolving power. 
C)  staining techniques. 
D)  adding a blue filter to the light path.

Question 14

The first step in the Gram-stain sequence is the application of _______, which is the primary stain.

Accepted Answer

A)  safranin 
B)  crystal violet 
C)  Gram's iodine 
D)  Gram's decolorizer 
A)  safranin 
B)  crystal violet 
C)  Gram's iodine 
D)  Gram's decolorizer

Question 15

The most critical step in the Gram stain is the application of the:

Accepted Answer

A)  safranin. 
B)  crystal violet. 
C)  Gram's iodine. 
D)  Gram's decolorizer. 
A)  safranin. 
B)  crystal violet. 
C)  Gram's iodine. 
D)  Gram's decolorizer.

Exam 6: Role of Microscopy

The acid-fast stain is specifically designed for bacteria whose cell walls contain:

Bacterial cells with thick peptidoglycan and numerous teichoic acid cross-linkages are Gram stained.The organisms stain pink.Which one of the following statements explains this discrepancy?

The fluorochrome stain that can be used to detect mycobacteria is:

An organism such as Mycobacterium tuberculosis would absorb which stain in its cell wall?

Of the different types of staining and microscopic techniques, which one of the following is basically the most sensitive?

Magnifications in excess of 100,000 ´ are achieved by ________ microscopy?

A mordant that is applied after the primary stain to bond chemically the alkaline dye to the bacterial cell wall is:

Which of the following statements is true concerning dark-field microscopy?

After which step in the Gram-stain procedure are gram-positive bacteria first distinguished from gram-negative bacteria?

In microscopy, resolution can be defined as the:

The fluorochrome stain used to study a fungus is:

In the Kinyoun acid-fast staining method, ______ replaces _____ in the primary stain solution.

Contrast in microscopy is most commonly achieved by:

The first step in the Gram-stain sequence is the application of _______, which is the primary stain.

The most critical step in the Gram stain is the application of the:

Microbial Taxonomy

Bacterial Genetics, Metabolism, and Structure

Host-Microorganism Interactions

Laboratory Safety

Specimen Management

Traditional Cultivation and Identification

Nucleic Acid-Based Analytic Methods for Microbial Identification and Characterization

Immunochemical Methods Used for Organism Detection

Serologic Diagnosis of Infectious Diseases

Principles of Antimicrobial Action and Resistance

Laboratory Methods and Strategies for Antimicrobial Susceptibility Testing

Staphylococcus Micrococcus and Similar Organisms

Streptococcus Enterococcus and Similar Organisms

Bacillus and Similar Organisms

Listeria Corynebacterium and Similar Organisms

Erysipelothrix Lactobacillus and Similar Organisms

Nocardia Streptomyces Rhodococcus and Similar Organisms

Enterobacteriaceae

Acinetobacter, Stenotrophomonas, and Other Organisms

Pseudomonas, Burkholderia, and Similar Organisms

Rhizobium, Ochrobactrum, and Similar Organisms

Chryseobacterium, Sphingobacterium, and Similar Organisms

Alcaligenes, Bordetella Nonpertussis, Comamonas, and Similar Organisms

Vibrio, Aeromonas, Chromobacterium, and Related Organisms

Sphingomonas Paucimobilis and Similar Organisms

Moraxella and Related Organisms

Eikenella and Similar Organisms

Pasteurella and Similar Organisms

Actinobacillus, Aggregatibacter, Kingella, Cardiobacterium, Capnocytophaga, and Similar Organisms

Haemophilus

Bartonella and Afipia

Campylobacter, Arcobacter, and Helicobacter

Legionella

Brucella

Bordetella Pertussis, Bordetella Parapertussis, and Related Species

Francisella

Streptobacillus Moniliformis and Spirillum Minus

Neisseria and Moraxella Catarrhalis

Overview and General Considerations

Overview of Anaerobic Organisms

Mycobacteria

Obligate Intracellular and Non-culturable Bacterial Agents

Cell Walldeficient Bacteria: Mycoplasma and Ureaplasma

The Spirochetes

Laboratory Methods for Diagnosis of Parasitic Infections: Overview

Intestinal Protozoa

Blood and Tissue Protozoa

Other Protozoa

Intestinal Nematodes Roundworms

Tissue Nematodes Roundworms

Blood and Tissue Filarialnematodes

Intestinal Cestodes

Tissue Cestodes

Intestinal Trematodes

Liver and Lung Trematodes

Blood Trematodes

Overview of Fungal Identification Methods and Strategies

Hyaline Molds, Mucorales Zygomycetes, Dermatophytes, and Opportunitistic and Systemic Mycoses

Dematiaceous Melanizedmolds

Opportunistic Atypical Fungus: Pneumocystis Jiroveci

The Yeasts

Anti-fungal Susceptibility Testing, Therapy, and Prevention

Overview of the Methods and Strategies in Virology

Viruses in Human Disease

In the Kinyoun acid-fast staining method, __ replaces _ in the primary stain solution.