Question 1

Which of the following is a reason for the occurrence of a lag phase in a bacterial growth curve?

Accepted Answer

A)   The cells may be old and depleted of ATP, essential cofactors, and ribosomes that must be synthesized before growth can begin.
B)   The medium may be different from the previous growth medium so that the cells must synthesize new enzymes to use different nutrients.
C)   The organisms may have been injured and require time to recover.
D)   All of these are potential reasons.E) B) and C)
F) A) and B)

Question 2

Organisms that have their optimum growth pH between 5.5 and 8.0 are called __________.

Accepted Answer

The answer of Organisms that have their optimum growth pH...

Question 3

When a young, vigorously growing culture of bacteria is transferred to fresh medium of the same composition, the lag phase is usually short or absent.

Accepted Answer

A) True 
 B)False

Question 4

When a young, vigorously growing culture of bacteria is transferred to fresh medium of different composition, the lag phase is usually short or absent.

Accepted Answer

A) True 
 B)False

Question 5

An open system in which the growth rate is maintained by the removal and addition of media at such a rate as to maintain a constant cell density is called a

Accepted Answer

A)   manostat.
B)   chemostat.
C)   turbidostat.
D)   culturostat.E) None of the above
F) A) and C)

Question 6

At 4:00 p.m. a closed flask of sterile broth is inoculated with 10,000 cells. The lag phase lasts 1 hour. At 9:00 p.m. the log phase culture has a population of 65 million cells. The mean generation time is approximately

Accepted Answer

A)   10 minutes.
B)   20 minutes.
C)   30 minutes.
D)   40 minutes.E) A) and C)
F) B) and C)

Question 7

All bacterial and archaeal cells are diploid.

Accepted Answer

A) True 
 B)False

Question 8

The process of forming a cross wall between two daughter cells is known as

Accepted Answer

A)   replication
B)   septation
C)   sporulation
D)   mitosisE) A) and D)
F) A) and C)

Question 9

In a continuous culture system, the rate at which media is added and removed is called the __________ rate.

Accepted Answer

A)   dilution
B)   chemostatic
C)   pass-through
D)   flow-throughE) A) and B)
F) None of the above

Question 10

At 4:00 p.m. a closed flask of sterile broth is inoculated with 10,000 cells. The lag phase lasts 1 hour. At 9:00 p.m. the log phase culture has population of 65 million cells. The approximate number of generations that has occurred is

Accepted Answer

A)   5.
B)   13.
C)   21.
D)   27.E) A) and D)
F) C) and D)

Question 11

The limitation on microbial growth rate at high nutrient levels is

Accepted Answer

A)   the rate of protein synthesis.
B)   the rate of DNA replication.
C)   the saturation of the transport proteins for nutrient uptake.
D)   all of the choices.E) A) and B)
F) C) and D)

Question 12

The length of the lag phase of growth can vary depending on

Accepted Answer

A)   the condition of the microorganisms.
B)   the nature of the growth medium.
C)   the temperature.
D)   all of the choicesE) None of the above
F) B) and C)

Question 13

Microbial __________ is an increase in cell constituents that may or may not be accompanied by an increase in cell number.

Accepted Answer

The answer of Microbial __________ is an increase in cell...

Question 14

Organisms that grow best at pH levels above 10 are called __________ __________.

Accepted Answer

extreme al...

Question 15

When a microorganism is placed in a(n)  __________ solution, water will enter into the cell and cause it to burst unless something is done to prevent this.

Accepted Answer

A)   hypotonic
B)   isotonic
C)   hypertonic
D)   osmotonicE) All of the above
F) A) and B)

Question 16

Quorum sensing in Gram-positive bacteria generally involves the use of ____________ as the external signaling molecules.

Accepted Answer

The answer of Quorum sensing in Gram-positive bacteria generally involves...

Question 17

At 4:00 p.m. a closed flask of sterile broth is inoculated with 10,000 cells. The lag phase lasts 1 hour. At 9:00 p.m. the culture enters stationary phase with a population of 65 million cells. At what time is the population half maximal?

Accepted Answer

A)   6:30 p.m
B)   7:20 p.m
C)   8:20 p.m
D)   8:40 p.mE) A) and D)
F) A) and C)

Question 18

The primary mechanism by which DNA is damaged by ultraviolet radiation involves the formation of thymine dimers.

Accepted Answer

A) True 
 B)False

Question 19

The site at which replication of DNA starts in bacterial cells is known as the __________ of ___________.

Accepted Answer

The answer of The site at which replication of DNA...

Question 20

Organisms that require increased pressure for optimum growth are called

Accepted Answer

A)   barotolerant.
B)   osmotolerant.
C)   barophilic.
D)   osmophilic.E) None of the above
F) C) and D)

Exam 7: Microbial Growth

An open system in which the growth rate is maintained by the removal and addition of media at such a rate as to maintain a constant cell density is called a

Correct AnswerverifiedShow Answer

Organisms that grow best at pH levels above 10 are called __________ __________.

Correct Answerverifiedextreme al...View AnswerShow Answer

In a continuous culture system, the rate at which media is added and removed is called the __________ rate.

Correct AnswerverifiedShow Answer

At 4:00 p.m. a closed flask of sterile broth is inoculated with 10,000 cells. The lag phase lasts 1 hour. At 9:00 p.m. the log phase culture has population of 65 million cells. The approximate number of generations that has occurred is

Correct AnswerverifiedShow Answer

The limitation on microbial growth rate at high nutrient levels is

Correct AnswerverifiedShow Answer

Microbial __________ is an increase in cell constituents that may or may not be accompanied by an increase in cell number.

Correct AnswerverifiedShow Answer

Which of the following is a reason for the occurrence of a lag phase in a bacterial growth curve?

Correct AnswerverifiedShow Answer

All bacterial and archaeal cells are diploid.

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Organisms that require increased pressure for optimum growth are called

Correct AnswerverifiedShow Answer

At 4:00 p.m. a closed flask of sterile broth is inoculated with 10,000 cells. The lag phase lasts 1 hour. At 9:00 p.m. the culture enters stationary phase with a population of 65 million cells. At what time is the population half maximal?

Correct AnswerverifiedShow Answer

The site at which replication of DNA starts in bacterial cells is known as the __________ of ___________.

Correct AnswerverifiedShow Answer

When a young, vigorously growing culture of bacteria is transferred to fresh medium of the same composition, the lag phase is usually short or absent.

Correct AnswerverifiedShow Answer

When a microorganism is placed in a(n) __________ solution, water will enter into the cell and cause it to burst unless something is done to prevent this.

Correct AnswerverifiedShow Answer

When a young, vigorously growing culture of bacteria is transferred to fresh medium of different composition, the lag phase is usually short or absent.

Correct AnswerverifiedShow Answer

Quorum sensing in Gram-positive bacteria generally involves the use of ____________ as the external signaling molecules.

Correct AnswerverifiedShow Answer

The primary mechanism by which DNA is damaged by ultraviolet radiation involves the formation of thymine dimers.

Correct AnswerverifiedShow Answer

Organisms that have their optimum growth pH between 5.5 and 8.0 are called __________.

Correct AnswerverifiedShow Answer

The length of the lag phase of growth can vary depending on

Correct AnswerverifiedShow Answer

At 4:00 p.m. a closed flask of sterile broth is inoculated with 10,000 cells. The lag phase lasts 1 hour. At 9:00 p.m. the log phase culture has a population of 65 million cells. The mean generation time is approximately

Correct AnswerverifiedShow Answer

The process of forming a cross wall between two daughter cells is known as

Correct AnswerverifiedShow Answer

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Organisms that grow best at pH levels above 10 are called .

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extreme al...
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The site at which replication of DNA starts in bacterial cells is known as the of _.

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