Question 1

Which of the following techniques can visualize bacteria without focusing electromagnetic radiation?

Accepted Answer

A)  cryo-electron microscopy 
B)  phase-contrast microscopy 
C)  dark-field microscopy 
D)  atomic force microscopy 
E)  X-ray diffraction 
A)  cryo-electron microscopy 
B)  phase-contrast microscopy 
C)  dark-field microscopy 
D)  atomic force microscopy 
E)  X-ray diffraction D

Question 2

Why do some bacteria appear purple after being Gram stained, while others appear pink?

Accepted Answer

Gram-negative cells have a few layers of peptidoglycan cell wall and an outer lipopolysaccharide membrane. Gram-positive organisms have several layers of peptidoglycan and no outer membrane. The multiple layers of peptidoglycan retain the crystal violet-iodine complex, so appear purple. Gram-negative cells do not retain the crystal violet because there are few layers of peptidoglycan and the outer membrane is disrupted by the decolorizer.

Question 3

If your eyes had photoreceptors packed as closely as an eagle's (about eight times greater than humans), would you be able to resolve a virus (100 nm in size) using a light microscope? Why or why not?

Accepted Answer

No. Although your resolving power would be much improved, the light microscope's power will still be limited by the wavelengths of light that you can see (roughly 400 nm for human eyes). Objects less than 400 nm cannot be resolved by light in the visible spectrum.

Question 4

Which of the following is best visualized using a negative stain?

Accepted Answer

A)  Gram-negative cell wall 
B)  acid-fast cell wall 
C)  capsule 
D)  endospores 
E)  flagella 
A)  Gram-negative cell wall 
B)  acid-fast cell wall 
C)  capsule 
D)  endospores 
E)  flagella

Question 5

Which of these techniques would provide the best resolution of an enzyme's structure?

Accepted Answer

A)  scanning electron microscopy 
B)  transmission electron microscopy 
C)  cryo-EM 
D)  X-ray diffraction analysis 
E)  atomic force microscopy 
A)  scanning electron microscopy 
B)  transmission electron microscopy 
C)  cryo-EM 
D)  X-ray diffraction analysis 
E)  atomic force microscopy

Question 6

Fluorescence microscopy using labeled antibodies is referred to as

Accepted Answer

A)  immunofluorescence. 
B)  autofluorescence. 
C)  confocal microscopy. 
D)  phase-contrast microscopy. 
E)  dark-field microscopy. 
A)  immunofluorescence. 
B)  autofluorescence. 
C)  confocal microscopy. 
D)  phase-contrast microscopy. 
E)  dark-field microscopy.

Question 7

Which type of microscopy is used to view the internal structures of a specimen?

Accepted Answer

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

Question 8

The part of the human eye that is MOST involved in resolving an image is the

Accepted Answer

A)  iris. 
B)  lens. 
C)  optic nerve. 
D)  retina. 
E)  cornea. 
A)  iris. 
B)  lens. 
C)  optic nerve. 
D)  retina. 
E)  cornea.

Question 9

When two waves are out of phase by ________ wavelength, they produce destructive interference, canceling each other's amplitude and resulting in contrast in the image.

Accepted Answer

A)  one-tenth of a 
B)  one-eighth of a 
C)  one-quarter of a 
D)  one-half of a 
E)  one 
A)  one-tenth of a 
B)  one-eighth of a 
C)  one-quarter of a 
D)  one-half of a 
E)  one

Question 10

Which of these series arranges microbes from smallest to largest?

Accepted Answer

A)  virus bacterium red blood cell paramecium 
B)  virus red blood cell bacterium paramecium 
C)  bacterium virus paramecium red blood cell 
D)  bacterium virus red blood cell paramecium 
E)  paramecium red blood cell bacterium virus 
A)  virus bacterium red blood cell paramecium 
B)  virus red blood cell bacterium paramecium 
C)  bacterium virus paramecium red blood cell 
D)  bacterium virus red blood cell paramecium 
E)  paramecium red blood cell bacterium virus

Question 11

The spots recorded on film during X-ray diffraction analyses are due to

Accepted Answer

A)  artifacts. 
B)  scattering. 
C)  wave interference. 
D)  absorption. 
E)  fluorescence. 
A)  artifacts. 
B)  scattering. 
C)  wave interference. 
D)  absorption. 
E)  fluorescence.

Question 12

What is the best explanation for a Gram-positive bacterium appearing pink after performing a Gram stain?

Accepted Answer

A)  The crystal violet was left on for too long. 
B)  The iodine was left on for too long. 
C)  The decolorizer was left on for too long. 
D)  The safranin was left on for too long. 
E)  The stain was properly performed. 
A)  The crystal violet was left on for too long. 
B)  The iodine was left on for too long. 
C)  The decolorizer was left on for too long. 
D)  The safranin was left on for too long. 
E)  The stain was properly performed.

Question 13

Which of the following methods is used to generate the structure shown below?

Accepted Answer

A)  scanning probe microscopy 
B)  scanning electron microscopy 
C)  transmission electron microscopy 
D)  confocal microscopy 
E)  X-ray crystallography 
A)  scanning probe microscopy 
B)  scanning electron microscopy 
C)  transmission electron microscopy 
D)  confocal microscopy 
E)  X-ray crystallography

Question 14

Microbes were detected long before the invention of the microscope. How could this be?

Accepted Answer

Detection is the ability to observe the

Question 15

One advantage of a wet mount is

Accepted Answer

A)  low contrast. 
B)  that the organism is still. 
C)  viewing in a natural state. 
D)  high contrast. 
E)  that the sample does not overheat. 
A)  low contrast. 
B)  that the organism is still. 
C)  viewing in a natural state. 
D)  high contrast. 
E)  that the sample does not overheat.

Question 16

Which type of microscopy is used to identify the 3-D structure of biofilms?

Accepted Answer

A)  phase-contrast 
B)  dark-field 
C)  florescent 
D)  bright-field 
E)  confocal 
A)  phase-contrast 
B)  dark-field 
C)  florescent 
D)  bright-field 
E)  confocal

Question 17

Describe three methods of sample preparation for electron microscopy. Which method would cause the fewest artifacts? Why?

Accepted Answer

(1) Samples can be embedded in a polymer

Question 18

A ball-shaped microbe is referred to as a

Accepted Answer

A)  bacillus. 
B)  coccus. 
C)  vibrio. 
D)  strepto. 
E)  spirochete. 
A)  bacillus. 
B)  coccus. 
C)  vibrio. 
D)  strepto. 
E)  spirochete.

Question 19

In which type of microscopy do dust particles interfere the MOST?

Accepted Answer

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

Question 20

List and describe three common shapes of bacteria.

Accepted Answer

Bacilli (bacillus in the singu

Exam 2: Observing the Microbial Cell

Which of the following techniques can visualize bacteria without focusing electromagnetic radiation?

Why do some bacteria appear purple after being Gram stained, while others appear pink?

If your eyes had photoreceptors packed as closely as an eagle's (about eight times greater than humans), would you be able to resolve a virus (100 nm in size) using a light microscope? Why or why not?

Which of the following is best visualized using a negative stain?

Which of these techniques would provide the best resolution of an enzyme's structure?

Fluorescence microscopy using labeled antibodies is referred to as

Which type of microscopy is used to view the internal structures of a specimen?

The part of the human eye that is MOST involved in resolving an image is the

When two waves are out of phase by ________ wavelength, they produce destructive interference, canceling each other's amplitude and resulting in contrast in the image.

Which of these series arranges microbes from smallest to largest?

The spots recorded on film during X-ray diffraction analyses are due to

What is the best explanation for a Gram-positive bacterium appearing pink after performing a Gram stain?

Which of the following methods is used to generate the structure shown below?

Microbes were detected long before the invention of the microscope. How could this be?

One advantage of a wet mount is

Which type of microscopy is used to identify the 3-D structure of biofilms?

Describe three methods of sample preparation for electron microscopy. Which method would cause the fewest artifacts? Why?

A ball-shaped microbe is referred to as a

In which type of microscopy do dust particles interfere the MOST?

List and describe three common shapes of bacteria.

Microbial Life: Origin and Discovery

Cell Structure and Function

Bacterial Culture, Growth, and Development

Environmental Influences and Control of Microbial Growth

Viruses

Genomes and Chromosomes

Transcription, Translation, and Bioinformatics

Gene Transfer, Mutations, and Genome Evolution

Molecular Regulation

Viral Molecular Biology

Biotechniques and Synthetic Biology

Energetics and Catabolism

Electron Flow in Organotrophy, Lithotrophy, and Phototrophy

Biosynthesis

Food and Industrial Microbiology

Origins and Evolution

Bacterial Diversity

Archaeal Diversity

Eukaryotic Diversity

Microbial Ecology

Microbes in Global Elemental Cycles

Human Microbiota and Innate Immunity

The Adaptive Immune Response

Microbial Pathogenesis

Microbial Diseases

Antimicrobial Therapy

Clinical Microbiology and Epidemiology

Filters