Question 1

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 B

Question 2

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 import sodium ions with other solutes. Halophiles have evolved to require high intracellular levels of potassium ions. In fact, ribosomes actually require high levels of potassium to maintain structural integrity and function. To achieve this, halophiles have a sodium/potassium antiport system. Sodium ions are pumped out of the cell so that the compatible solute, potassium ions, may be brought into the cell.

Question 3

If you have a food sample contaminated with anthrax spores, which sterilization approach would make sure the sample is free of spores without compromising the quality of the food sample-autoclaving or irradiation? Why?

Accepted Answer

Although both autoclaving and irradiation would provide a spore-free food sample at the end of the process, the autoclave's high pressure and temperature might compromise important ingredients in the food sample. However, when the food sample is irradiated, water and other intracellular molecules absorb energy and form transient reactive chemicals that damage the DNA, and thereby destroy the spores without compromising the quality of the food sample.

Question 4

The use of oxygen as the terminal electron acceptor is called

Accepted Answer

A)  aerobic respiration. 
B)  anaerobic respiration. 
C)  fermentation. 
D)  oxygenic photosynthesis. 
E)  carbon dioxide fixation. 
A)  aerobic respiration. 
B)  anaerobic respiration. 
C)  fermentation. 
D)  oxygenic photosynthesis. 
E)  carbon dioxide fixation.

Question 5

Which of the following enzymes are stable in part because they contain relatively low amounts of the small amino acid glycine?

Accepted Answer

A)  psychrophilic 
B)  acidophilic 
C)  thermophilic 
D)  halophilic 
E)  barophilic 
A)  psychrophilic 
B)  acidophilic 
C)  thermophilic 
D)  halophilic 
E)  barophilic

Question 6

How does pH affect proteins? Why do proteins have an optimum, minimum, and maximum pH at which they will function?

Accepted Answer

The charges on amino or carboxyl groups

Question 7

Which of the following are often chemolithotrophs 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 8

How is the phenol coefficient calculated? Why is phenol the standard for testing other disinfectants?

Accepted Answer

Because of its potency and its history,

Question 9

The D-value of a bacterial culture heated to 100°C is the time it takes to kill ________% of the population.

Accepted Answer

A)  99 
B)  90 
C)  50 
D)  10 
E)  1 
A)  99 
B)  90 
C)  50 
D)  10 
E)  1

Question 10

E. coli tolerates a pH range from 2 to 9, which is a ________-fold difference in hydrogen ion concentration.

Accepted Answer

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

Question 11

One function of programmed cell death is to

Accepted Answer

A)  increase the pH of the local environment. 
B)  release antibiotic resistance compounds. 
C)  increase the solute concentration of a hypotonic solution. 
D)  decrease the pH of the local environment. 
E)  release nutrients that neighboring cells use to survive. 
A)  increase the pH of the local environment. 
B)  release antibiotic resistance compounds. 
C)  increase the solute concentration of a hypotonic solution. 
D)  decrease the pH of the local environment. 
E)  release nutrients that neighboring cells use to survive.

Question 12

Why do some microorganisms produce antibiotics, and how do they avoid being harmed by the antibiotics they produce?

Accepted Answer

Answers will vary. Microbes make antibio

Question 13

The fastest growth rate for a species occurs at temperatures where a cell's ________ work most efficiently.

Accepted Answer

A)  lipids 
B)  membranes 
C)  nucleic acids 
D)  proteins 
E)  polysaccharides 
A)  lipids 
B)  membranes 
C)  nucleic acids 
D)  proteins 
E)  polysaccharides

Question 14

Which of the following is true of microbes and their membranes?

Accepted Answer

A)  They are relatively permeable to protons. 
B)  Protons can leak through directly when the difference in intracellular and extracellular pH is very high. 
C)  Membrane-permeant organic acids can prevent the leakage of protons. 
D)  They are able to change the pH optima of their enzymes. 
E)  Acidophiles use Na+/H+ antiporters to remove internal protons. 
A)  They are relatively permeable to protons. 
B)  Protons can leak through directly when the difference in intracellular and extracellular pH is very high. 
C)  Membrane-permeant organic acids can prevent the leakage of protons. 
D)  They are able to change the pH optima of their enzymes. 
E)  Acidophiles use Na+/H+ antiporters to remove internal protons.

Question 15

Which of the conditions can be labeled as "extreme"?

Accepted Answer

A)  near-neutral pH 
B)  25°C 
C)  pressure of 400 atm 
D)  a salt concentration of 0.9% 
E)  pressure of 14 psi 
A)  near-neutral pH 
B)  25°C 
C)  pressure of 400 atm 
D)  a salt concentration of 0.9% 
E)  pressure of 14 psi

Question 16

Deinococcus radiodurans resists extreme drought and radiation by what mechanism?

Accepted Answer

A)  biofilm formation 
B)  producing aquaporins 
C)  producing multidrug efflux pumps 
D)  endospore formation 
E)  repairing DNA damage 
A)  biofilm formation 
B)  producing aquaporins 
C)  producing multidrug efflux pumps 
D)  endospore formation 
E)  repairing DNA damage

Question 17

A useful biocontrol alternative to antibiotics for treatment of biofilms that can potentially lead to chronic infections is

Accepted Answer

A)  phenolics. 
B)  high temperatures and pressures. 
C)  commercial disinfectants. 
D)  x-rays. 
E)  bacteriophages. 
A)  phenolics. 
B)  high temperatures and pressures. 
C)  commercial disinfectants. 
D)  x-rays. 
E)  bacteriophages.

Question 18

All of the following are true about microbes and temperature EXCEPT

Accepted Answer

A)  microbes have mechanisms to control their temperature. 
B)  temperature affects the average rate of molecular motion. 
C)  changes in temperature affect membrane fluidity. 
D)  changes in temperature affect transport. 
E)  every organism has an optimum temperature for growth. 
A)  microbes have mechanisms to control their temperature. 
B)  temperature affects the average rate of molecular motion. 
C)  changes in temperature affect membrane fluidity. 
D)  changes in temperature affect transport. 
E)  every organism has an optimum temperature for growth.

Question 19

What is biocontrol? Describe two examples.

Accepted Answer

Answers will vary. Biocontrol is the use

Question 20

Which of the following is NOT true concerning irradiation of foods?

Accepted Answer

A)  Food consumed by NASA astronauts is sterilized by irradiation. 
B)  Foods become radioactive when irradiated. 
C)  Viruses are resistant to doses approved for foods. 
D)  A higher dose of radiation is necessary to kill microbes in frozen foods. 
E)  It is effective in eliminating parasites and bacteria. 
A)  Food consumed by NASA astronauts is sterilized by irradiation. 
B)  Foods become radioactive when irradiated. 
C)  Viruses are resistant to doses approved for foods. 
D)  A higher dose of radiation is necessary to kill microbes in frozen foods. 
E)  It is effective in eliminating parasites and bacteria.

Exam 5: Environmental Influences and Control of Microbial Growth

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

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

If you have a food sample contaminated with anthrax spores, which sterilization approach would make sure the sample is free of spores without compromising the quality of the food sample-autoclaving or irradiation? Why?

The use of oxygen as the terminal electron acceptor is called

Which of the following enzymes are stable in part because they contain relatively low amounts of the small amino acid glycine?

How does pH affect proteins? Why do proteins have an optimum, minimum, and maximum pH at which they will function?

Which of the following are often chemolithotrophs that oxidize reduced metals and generate strong acids, such as sulfuric acid?

How is the phenol coefficient calculated? Why is phenol the standard for testing other disinfectants?

The D-value of a bacterial culture heated to 100°C is the time it takes to kill ________% of the population.

E. coli tolerates a pH range from 2 to 9, which is a ________-fold difference in hydrogen ion concentration.

One function of programmed cell death is to

Why do some microorganisms produce antibiotics, and how do they avoid being harmed by the antibiotics they produce?

The fastest growth rate for a species occurs at temperatures where a cell's ________ work most efficiently.

Which of the following is true of microbes and their membranes?

Which of the conditions can be labeled as "extreme"?

Deinococcus radiodurans resists extreme drought and radiation by what mechanism?

A useful biocontrol alternative to antibiotics for treatment of biofilms that can potentially lead to chronic infections is

All of the following are true about microbes and temperature EXCEPT

What is biocontrol? Describe two examples.

Which of the following is NOT true concerning irradiation of foods?

Microbial Life: Origin and Discovery

Observing the Microbial Cell

Cell Structure and Function

Bacterial Culture, Growth, and Development

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

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