Question 1

What is biocontrol? Describe two examples.

Accepted Answer

Answers will vary. Biocontrol is the use...

Question 2

Which of the following grows in the indicated pH range shown in the figure below?

Accepted Answer

A)   psychrophiles
B)   mesophiles
C)   piezophiles
D)   alkaliphiles
E)   acidophiles

Question 3

Most bacteria require water activity to be greater than

Accepted Answer

A)   0.10.
B)   0.25.
C)   0.74.
D)   0.91.
E)   1.0.

Question 4

Human pathogens are

Accepted Answer

A)   halophilic.
B)   psychrophilic.
C)   mesophilic.
D)   thermophilic.
E)   extreme thermophilic.

Question 5

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.

Question 6

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

Question 7

The conditions used in an autoclave may be reproduced at home in

Accepted Answer

A)   a rice cooker.
B)   a double-boiler.
C)   a microwave.
D)   a pressure cooker.
E)   boiling water.

Question 8

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.

Question 9

Which of the following are commonly used to control microbial growth in foods?

Accepted Answer

A)   weak acids
B)   strong acids
C)   weak bases
D)   strong bases
E)   enzymes

Question 10

What is depicted in the following figure?

Accepted Answer

A)   Antibiotic production has inhibited bacterial growth.
B)   A bacteriophage has preyed on the bacterial colonies.
C)   Weak acid production has inhibited bacterial growth.
D)   A biofilm has become resistant to disinfectants.
E)   Starving cells have undergone programmed cell death.

Question 11

Why are thermophiles able to survive at temperatures that would quickly kill most mesophiles? Describe at least three adaptations.

Accepted Answer

Thermophilic proteins are more stable du...

Question 12

The membrane needs to remain ________ so that it can expand as cells grow larger and so that proteins needed for solute transport can be inserted into the membrane.

Accepted Answer

A)   rigid
B)   warm
C)   fluid
D)   hypertonic
E)   polarized

Question 13

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.

Question 14

Why is moist heat more efficient at killing microbes than dry heat? How does an autoclave kill microbes so efficiently?

Accepted Answer

Moist heat is a more effective killer th...

Question 15

Runoff from agricultural fields, lawns, and golf courses can cause an overgrowth of microbes due to

Accepted Answer

A)   eutrophication.
B)   starvation response.
C)   oligotrophy.
D)   antisepsis.
E)   pasteurization.

Question 16

Cyanobacterial blooms such as those shown in the figure below are typically due to human-caused

Accepted Answer

A)   antibiotic resistance.
B)   warming.
C)   oxygenation.
D)   salinity increase.
E)   eutrophication.

Question 17

During the starvation response, only a limited number of organisms can

Accepted Answer

A)   retool transport systems for the uptake of different nutrients.
B)   form metabolically inactive endospores.
C)   protect against reactive oxygen species.
D)   protect against temperature extremes.
E)   protect against pH extremes.

Question 18

Describe the studies with Salmonella that showed that in vitro conditions do not always model what happens in vivo (in this case in the phagocytic vacuole).

Accepted Answer

Protein profiles were obtained in vitro ...

Question 19

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

Accepted Answer

Some organisms exhibit heat-sh...

Question 20

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

Exam 5: Environmental Influences and Control of Microbial Growth

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

Correct AnswerverifiedShow Answer

The membrane needs to remain ________ so that it can expand as cells grow larger and so that proteins needed for solute transport can be inserted into the membrane.

Correct AnswerverifiedShow Answer

Which of the following are commonly used to control microbial growth in foods?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Describe the studies with Salmonella that showed that in vitro conditions do not always model what happens in vivo (in this case in the phagocytic vacuole).

Correct AnswerverifiedProtein profiles were obtained in vitro ...View AnswerShow Answer

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

Correct AnswerverifiedShow Answer

The conditions used in an autoclave may be reproduced at home in

Correct AnswerverifiedShow Answer

Cyanobacterial blooms such as those shown in the figure below are typically due to human-caused

Correct AnswerverifiedShow Answer

Why is moist heat more efficient at killing microbes than dry heat? How does an autoclave kill microbes so efficiently?

Correct AnswerverifiedMoist heat is a more effective killer th...View AnswerShow Answer

Which of the following grows in the indicated pH range shown in the figure below?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedSome organisms exhibit heat-sh...View AnswerShow Answer

The use of oxygen as the terminal electron acceptor is called

Correct AnswerverifiedShow Answer

Most bacteria require water activity to be greater than

Correct AnswerverifiedShow Answer

Human pathogens are

Correct AnswerverifiedShow Answer

What is depicted in the following figure?

Correct AnswerverifiedShow Answer

What is biocontrol? Describe two examples.

Correct AnswerverifiedAnswers will vary. Biocontrol is the use...View AnswerShow Answer

During the starvation response, only a limited number of organisms can

Correct AnswerverifiedShow Answer

Why are thermophiles able to survive at temperatures that would quickly kill most mesophiles? Describe at least three adaptations.

Correct AnswerverifiedThermophilic proteins are more stable du...View AnswerShow Answer

Runoff from agricultural fields, lawns, and golf courses can cause an overgrowth of microbes due to

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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Protein profiles were obtained in vitro ...
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Moist heat is a more effective killer th...
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Some organisms exhibit heat-sh...
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Answers will vary. Biocontrol is the use...
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Thermophilic proteins are more stable du...
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