Question 1

Briefly describe three techniques used to culture anaerobes in the laboratory.

Accepted Answer

Liquid media that contain reducing agents that eliminate dissolved oxygen can be used. Portions of the liquid below the surface will be free of oxygen and support anaerobic growth.
Agar media can be placed into anaerobic jars, which are sealed with chemicals that react with free oxygen, thus generating an anaerobic environment.
An anaerobic glove box is a sealed incubation chamber in which the atmosphere is free of oxygen.

Question 2

An organism that grows at the bottom of a tube of thioglycolate broth medium is probably a(n):

Accepted Answer

A)  strict aerobe 
B)  facultative anaerobe 
C)  aerotolerant anaerobe 
D)  microaerophile 
E)  strict anaerobe 
A)  strict aerobe 
B)  facultative anaerobe 
C)  aerotolerant anaerobe 
D)  microaerophile 
E)  strict anaerobe E

Question 3

Which pair of traits can the same organism have?

Accepted Answer

A)  obligate aerobe; obligate anaerobe 
B)  Gram-positive; Gram-negative 
C)  thermophile; facultative anaerobe 
D)  obligate anaerobe; catalase producer 
E)  microaerophile; grows in 300 µM oxygen 
A)  obligate aerobe; obligate anaerobe 
B)  Gram-positive; Gram-negative 
C)  thermophile; facultative anaerobe 
D)  obligate anaerobe; catalase producer 
E)  microaerophile; grows in 300 µM oxygen C

Question 4

Which of the following is NOT true about thermophiles?

Accepted Answer

A)  Their proteins contain less glycine. 
B)  They have more unsaturated linear lipids in their membranes. 
C)  They have chaperone proteins. 
D)  Their genomes are packed with numerous DNA-binding proteins that stabilize DNA. 
E)  They have special enzymes that function to tightly coil DNA. 
A)  Their proteins contain less glycine. 
B)  They have more unsaturated linear lipids in their membranes. 
C)  They have chaperone proteins. 
D)  Their genomes are packed with numerous DNA-binding proteins that stabilize DNA. 
E)  They have special enzymes that function to tightly coil DNA.

Question 5

What alkaliphile do pink flamingos eat and how is it involved in making the flamingo pink?

Accepted Answer

The cyanobacterium Spirulina imparts a p

Question 6

What is biocontrol? Describe two examples.

Accepted Answer

Answers will vary. Biocontrol is the use

Question 7

Halophiles require high salt concentrations to survive. Describe a mechanism involving compatible solutes that has evolved to achieve low internal sodium ion concentrations.

Accepted Answer

Cells have symporter systems that will i

Question 8

Piezophile is another term for:

Accepted Answer

A)  acidophile 
B)  halophile 
C)  psychrophile 
D)  barotolerant 
E)  barophile 
A)  acidophile 
B)  halophile 
C)  psychrophile 
D)  barotolerant 
E)  barophile

Question 9

E. coli tolerates a pH range of 2-9, which is a what-fold difference in hydrogen ion concentration?

Accepted Answer

A)  7-fold 
B)  100-fold 
C)  1,000-fold 
D)  10,000-fold 
E)  10,000,000-fold 
A)  7-fold 
B)  100-fold 
C)  1,000-fold 
D)  10,000-fold 
E)  10,000,000-fold

Question 10

If a disinfectant is added to a culture containing 1 x 106 CFU per milliliter and the D-value of the disinfectant is 2 minutes, how many viable cells are left after 4 minutes of exposure?

Accepted Answer

The D-value is the time required to kill

Question 11

A __________ medium is one of higher osmolarity than the cell.

Accepted Answer

A)  hypertonic 
B)  hypotonic 
C)  isotonic 
D)  defined 
E)  complex 
A)  hypertonic 
B)  hypotonic 
C)  isotonic 
D)  defined 
E)  complex

Question 12

How are some organisms able to survive temporary exposures to elevated temperatures?

Accepted Answer

Some organisms exhibit heat-sh

Question 13

Psychrophiles favor the cold since their membranes are more fluid at low temperature as a result of the high proportion of __________ present.

Accepted Answer

A)  saturated fatty acids 
B)  unsaturated fatty acids 
C)  lipopolysaccharides 
D)  transport proteins 
E)  water 
A)  saturated fatty acids 
B)  unsaturated fatty acids 
C)  lipopolysaccharides 
D)  transport proteins 
E)  water

Question 14

Many __________ bacteria cause horrific human diseases, such as tetanus, botulism, and gangrene.

Accepted Answer

A)  aerobic 
B)  anaerobic 
C)  psychrophilic 
D)  halophilic 
E)  fermentative 
A)  aerobic 
B)  anaerobic 
C)  psychrophilic 
D)  halophilic 
E)  fermentative

Question 15

A bacterium that thrives in your stomach is probably a(n):

Accepted Answer

A)  thermophile 
B)  neutrophile 
C)  alkaliphile 
D)  acidophile 
E)  psychrophile 
A)  thermophile 
B)  neutrophile 
C)  alkaliphile 
D)  acidophile 
E)  psychrophile

Question 16

Many __________ have been isolated from the ocean floor environment.

Accepted Answer

A)  psychrophiles 
B)  mesophiles 
C)  thermophiles 
D)  barophiles 
E)  acidophiles 
A)  psychrophiles 
B)  mesophiles 
C)  thermophiles 
D)  barophiles 
E)  acidophiles

Question 17

__________ are often chemoautotrophs that oxidize reduced metals and generate strong acids such as sulfuric acid.

Accepted Answer

A)  Acidophiles 
B)  Psychrophiles 
C)  Halophiles 
D)  Mesophiles 
E)  Barophiles 
A)  Acidophiles 
B)  Psychrophiles 
C)  Halophiles 
D)  Mesophiles 
E)  Barophiles

Question 18

Which of the following uses microbes to detoxify environmental contaminants?

Accepted Answer

A)  PCR 
B)  DNA microarrays 
C)  DNA sequencing 
D)  antibioisis 
E)  bioremediation 
A)  PCR 
B)  DNA microarrays 
C)  DNA sequencing 
D)  antibioisis 
E)  bioremediation

Question 19

At the bottom of the ocean, hydrostatic pressure averages a crushing 400 atm (atmospheres) and can go as high as:

Accepted Answer

A)  700 atm 
B)  1,000 atm 
C)  1,500 atm 
D)  3,000 atm 
E)  3,500 atm 
A)  700 atm 
B)  1,000 atm 
C)  1,500 atm 
D)  3,000 atm 
E)  3,500 atm

Question 20

What is a neutralophile? Neutralophiles were once referred to as neutrophiles. Why is this no longer the case?

Accepted Answer

The term neutralophile refers to an orga

Exam 5: Environmental Influences and Control of Microbial Growth

Briefly describe three techniques used to culture anaerobes in the laboratory.

An organism that grows at the bottom of a tube of thioglycolate broth medium is probably a(n):

Which pair of traits can the same organism have?

Which of the following is NOT true about thermophiles?

What alkaliphile do pink flamingos eat and how is it involved in making the flamingo pink?

What is biocontrol? Describe two examples.

Halophiles require high salt concentrations to survive. Describe a mechanism involving compatible solutes that has evolved to achieve low internal sodium ion concentrations.

Piezophile is another term for:

E. coli tolerates a pH range of 2-9, which is a what-fold difference in hydrogen ion concentration?

If a disinfectant is added to a culture containing 1 x 106 CFU per milliliter and the D-value of the disinfectant is 2 minutes, how many viable cells are left after 4 minutes of exposure?

A __________ medium is one of higher osmolarity than the cell.

How are some organisms able to survive temporary exposures to elevated temperatures?

Psychrophiles favor the cold since their membranes are more fluid at low temperature as a result of the high proportion of __________ present.

Many __________ bacteria cause horrific human diseases, such as tetanus, botulism, and gangrene.

A bacterium that thrives in your stomach is probably a(n):

Many __________ have been isolated from the ocean floor environment.

__________ are often chemoautotrophs that oxidize reduced metals and generate strong acids such as sulfuric acid.

Which of the following uses microbes to detoxify environmental contaminants?

At the bottom of the ocean, hydrostatic pressure averages a crushing 400 atm (atmospheres) and can go as high as:

What is a neutralophile? Neutralophiles were once referred to as neutrophiles. Why is this no longer the case?

Microbial Life: Origin and Discovery

Observing the Microbial Cell

Cell Structure and Function

Bacterial Culture, Growth, and Development

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Electron Flow in Organotrophy, Lithotrophy, and Phototrophy

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Microbes in Global Elemental Cycles

Human Microbiota and Innate Immunity

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If a disinfectant is added to a culture containing 1 x 10⁶ CFU per milliliter and the D-value of the disinfectant is 2 minutes, how many viable cells are left after 4 minutes of exposure?