Question 1

Which step in the Gram stain is the critical step in differentiating gram-positive cells from gram-negative cells?

Accepted Answer

A)  crystal violet 
B)  safranin 
C)  alcohol-acetone 
D)  iodine 
A)  crystal violet 
B)  safranin 
C)  alcohol-acetone 
D)  iodine C

Question 2

A microorganism measures 5 μm in length. Its length in mm would be

Accepted Answer

A)  500 mm. 
B)  0.5 mm. 
C)  0.005 mm. 
D)  0.05 mm. 
E)  50 mm. 
A)  500 mm. 
B)  0.5 mm. 
C)  0.005 mm. 
D)  0.05 mm. 
E)  50 mm. C

Question 3

Bacterial smears are fixed before staining to

Accepted Answer

A)  accept stain. 
B)  affix the cells to the slide. 
C)  make the cells visible. 
D)  make their walls permeable. 
A)  accept stain. 
B)  affix the cells to the slide. 
C)  make the cells visible. 
D)  make their walls permeable. B

Question 4

In a completed Gram stain, gram-positive bacteria are purple.

Accepted Answer

A) True 
 B)False

Question 5

Which of the following is never useful for observing living cells?

Accepted Answer

A)  scanning electron microscope 
B)  phase-contrast microscope 
C)  scanning acoustic microscope 
D)  brightfield microscope 
E)  darkfield microscope 
A)  scanning electron microscope 
B)  phase-contrast microscope 
C)  scanning acoustic microscope 
D)  brightfield microscope 
E)  darkfield microscope

Question 6

You are performing a Gram stain on gram-negative bacteria and you stop after the addition of the mordant. What is the appearance of the bacteria at this point?

Accepted Answer

A)  purple 
B)  red 
C)  colorless 
D)  brown 
A)  purple 
B)  red 
C)  colorless 
D)  brown

Question 7

Which of the following correctly traces the path of light through the compound microscope?

Accepted Answer

A)  light source; specimen; condenser; objective lens; ocular lens 
B)  light source; condenser; specimen; objective lens; ocular lens 
C)  light source; condenser; objective lens; specimen; ocular lens 
D)  condenser; light source; specimen; ocular lens; objective lens 
E)  condenser; light source; specimen; objective lens; ocular lens 
A)  light source; specimen; condenser; objective lens; ocular lens 
B)  light source; condenser; specimen; objective lens; ocular lens 
C)  light source; condenser; objective lens; specimen; ocular lens 
D)  condenser; light source; specimen; ocular lens; objective lens 
E)  condenser; light source; specimen; objective lens; ocular lens

Question 8

A virus measures 100 nm in length. What is its length in μm?

Accepted Answer

A)  0.1 μm 
B)  1 μm 
C)  0.001 μm 
D)  10 μm 
E)  0.01 μm 
A)  0.1 μm 
B)  1 μm 
C)  0.001 μm 
D)  10 μm 
E)  0.01 μm

Question 9

Which of the following pairs is mismatched?

Accepted Answer

A)  crystal violet - basic dye 
B)  safranin - acid dye 
C)  alcohol-acetone - decolorizer 
D)  carbolfuchsin - basic dye 
E)  iodine - mordant 
A)  crystal violet - basic dye 
B)  safranin - acid dye 
C)  alcohol-acetone - decolorizer 
D)  carbolfuchsin - basic dye 
E)  iodine - mordant

Question 10

Figure 3.1   In Figure 3.1, line ʺcʺ points to the microscopeʹs

Accepted Answer

A)  illuminator. 
B)  ocular lens. 
C)  objective lens. 
D)  condenser. 
A)  illuminator. 
B)  ocular lens. 
C)  objective lens. 
D)  condenser.

Question 11

The resolution of a microscope can be improved by changing the

Accepted Answer

A)  condenser. 
B)  coarse adjustment. 
C)  diaphragm. 
D)  wavelength of light. 
E)  fine adjustment. 
A)  condenser. 
B)  coarse adjustment. 
C)  diaphragm. 
D)  wavelength of light. 
E)  fine adjustment.

Question 12

You are performing a Gram stain on gram-negative bacteria and you stop after the decolorizer step. What is the appearance of the bacteria at this point?

Accepted Answer

A)  purple 
B)  red 
C)  colorless 
D)  brown 
A)  purple 
B)  red 
C)  colorless 
D)  brown

Question 13

Which microscope is used to see detail of a 300 -nm virus?

Accepted Answer

A)  darkfield microscope 
B)  DIC microscope 
C)  fluorescence microscope 
D)  phase-contrast microscope 
E)  electron microscope 
A)  darkfield microscope 
B)  DIC microscope 
C)  fluorescence microscope 
D)  phase-contrast microscope 
E)  electron microscope

Question 14

Which of the following is NOT true regarding the acid-fast stain?

Accepted Answer

A)  Acid-fast cells appear red in a completed acid-fast stain. 
B)  It is used to identify members of the genus Mycobacterium. 
C)  Non-acid-fast microbes appear blue in a completed acid-fast stain. 
D)  Acid-fast cells retain the primary dye after treatment with acid -alcohol. 
E)  If cells are acid-fast, they are gram-negative. 
A)  Acid-fast cells appear red in a completed acid-fast stain. 
B)  It is used to identify members of the genus Mycobacterium. 
C)  Non-acid-fast microbes appear blue in a completed acid-fast stain. 
D)  Acid-fast cells retain the primary dye after treatment with acid -alcohol. 
E)  If cells are acid-fast, they are gram-negative.

Question 15

Which microscope takes advantage of differences in the refractive indexes of cell structures?

Accepted Answer

A)  compound light microscope 
B)  phase-contrast microscope 
C)  electron microscope 
D)  darkfield microscope 
E)  fluorescence microscope 
A)  compound light microscope 
B)  phase-contrast microscope 
C)  electron microscope 
D)  darkfield microscope 
E)  fluorescence microscope

Question 16

Simple staining is often necessary to improve contrast in which microscope?

Accepted Answer

A)  fluorescence microscope 
B)  phase-contrast microscope 
C)  compound light microscope 
D)  darkfield microscope 
E)  electron microscope 
A)  fluorescence microscope 
B)  phase-contrast microscope 
C)  compound light microscope 
D)  darkfield microscope 
E)  electron microscope

Question 17

Which microscope achieves the highest magnification and greatest resolution?

Accepted Answer

A)  darkfield microscope 
B)  electron microscope 
C)  compound light microscope 
D)  phase-contrast microscope 
E)  fluorescence microscope 
A)  darkfield microscope 
B)  electron microscope 
C)  compound light microscope 
D)  phase-contrast microscope 
E)  fluorescence microscope

Question 18

Which of the following is NOT equal to 1 mm?

Accepted Answer

A)  100 μm 
B)  10-3 m 
C)  106 nm 
D)  0.1 cm 
E)  0.001 m 
A)  100 μm 
B)  10-3 m 
C)  106 nm 
D)  0.1 cm 
E)  0.001 m

Question 19

Cells viewed in darkfield microscopy appear similar to those stained with the negative stain.

Accepted Answer

A) True 
 B)False

Question 20

You are performing a Gram stain on gram-positive bacteria and you stop after the addition of the counterstain. What is the appearance of the bacteria at this point?

Accepted Answer

A)  purple 
B)  red 
C)  colorless 
D)  brown 
A)  purple 
B)  red 
C)  colorless 
D)  brown

Exam 3: Observing Microorganisms Through a Microscope

Which step in the Gram stain is the critical step in differentiating gram-positive cells from gram-negative cells?

A microorganism measures 5 μm in length. Its length in mm would be

Bacterial smears are fixed before staining to

In a completed Gram stain, gram-positive bacteria are purple.

Which of the following is never useful for observing living cells?

You are performing a Gram stain on gram-negative bacteria and you stop after the addition of the mordant. What is the appearance of the bacteria at this point?

Which of the following correctly traces the path of light through the compound microscope?

A virus measures 100 nm in length. What is its length in μm?

Which of the following pairs is mismatched?

Figure 3.1 In Figure 3.1, line ʺcʺ points to the microscopeʹs

The resolution of a microscope can be improved by changing the

You are performing a Gram stain on gram-negative bacteria and you stop after the decolorizer step. What is the appearance of the bacteria at this point?

Which microscope is used to see detail of a 300 -nm virus?

Which of the following is NOT true regarding the acid-fast stain?

Which microscope takes advantage of differences in the refractive indexes of cell structures?

Simple staining is often necessary to improve contrast in which microscope?

Which microscope achieves the highest magnification and greatest resolution?

Which of the following is NOT equal to 1 mm?

Cells viewed in darkfield microscopy appear similar to those stained with the negative stain.

You are performing a Gram stain on gram-positive bacteria and you stop after the addition of the counterstain. What is the appearance of the bacteria at this point?

The Microbial World and You

Chemical Principles

Functional Anatomy of Prokaryotic and Eukaryotic Cells

Microbial Metabolism

Microbial Growth

The Control of Microbial Growth

Microbial Genetics

Biotechnology and Dna Technology

Classification of Microorganisms

The Prokaryotes: Domains Bacteria and Archaea

The Eukaryotes: Fungi, Algae, Protozoa, and Helminths

Viruses, Viroids, and Prions

Principles of Disease and Epidemiology

Microbial Mechanisms of Pathogenicity

Adaptive Immunity: Specific Defenses of the Host

Practical Applications of Immunology

Disorders Associated With the Immune System

Antimicrobial Drugs

Microbial Diseases of the Skin and Eyes

Microbial Diseases of the Nervous System

Microbial Diseases of the Cardiovascular and Lymphatic Systems

Microbial Diseases of the Respiratory System

Microbial Diseases of the Digestive System

Microbial Disease of the Urinary and Reproductive Systems

Environmental Microbiology

Applied and Industrial Microbiology

Innate Immunity: Nonspecific Defenses of the Host

Filters