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Organisms that have their optimum growth pH between 8.5 and 11.5 are called __________.

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The __________ __________ is the length of time it takes for a population of microorganisms to double in number.

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A microbial environment containing high nutrient concentrations is called an oligotrophic environment.

A) True
B) False

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Growth is said to be __________ when all cellular components are synthesized at constant rates relative to one another.

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balanced

The actin-like protein that seems to be involved in determining cell shape is


A) MreB.
B) ActA.
C) SpnC.
D) FtsZ.

E) A) and B)
F) A) and C)

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A

During the lag phase of microbial growth, the cells are metabolically inactive.

A) True
B) False

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Microorganisms are most nearly uniform in terms of chemical and physiological properties during __________ phase.


A) lag
B) exponential
C) stationary
D) decline

E) B) and D)
F) A) and C)

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Quorum sensing


A) is a phenomenon in which bacteria monitor their own population density.
B) depends on the sensing of signal protein molecules.
C) plays an important role in formation of biofilms by Pseudomonas aeruginosa.
D) all of the choices

E) A) and B)
F) B) and D)

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A culture system with constant environmental conditions maintained through continual provision of nutrient and removal of wastes is called __________ culture system.


A) continuous
B) batch
C) fed-batch
D) semicontinuous

E) C) and D)
F) A) and D)

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A

Organisms that grow at 0 °\degree C and have a maximum growth temperature of 35 °\degree C are called


A) psychrotrophs.
B) psychrophiles.
C) frigiphiles.
D) mesophiles.

E) A) and B)
F) A) and C)

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Organisms that do not require oxygen for growth but grow better in its presence are called


A) facultative anaerobes.
B) microaerophiles.
C) aerotolerant.
D) anoxygenic.

E) A) and D)
F) A) and C)

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Organisms that grow near deep-sea volcanic vents are likely to be


A) psychrophilic.
B) psychrotrophic.
C) mesophilic.
D) thermophilic.

E) None of the above
F) A) and D)

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A culture in a closed vessel to which no additional medium is added and from which no waste products are removed is called a __________ culture.


A) continuous
B) batch
C) fed-batch
D) semicontinuous

E) A) and D)
F) None of the above

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Most microorganisms maintain their internal pH


A) near neutral (pH 7) .
B) near their optimum growth pH.
C) slightly acidic (pH 4-6) .
D) slightly alkaline (pH 8-10) .

E) B) and C)
F) A) and D)

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The total number of viable microorganisms remains constant in stationary phase because


A) there is a balance between cell division and cell death.
B) there is a cessation of cell division even though the cells may remain metabolically active.
C) either there is a balance between cell division and cell death or there is a cessation of cell division even though the cells may remain metabolically active.
D) none of the choices

E) B) and D)
F) B) and C)

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Membranes of thermophilic bacteria are stabilized by phospholipids with


A) fatty acids that tend to be more saturated.
B) fatty acids that have lower molecular weights.
C) fatty acids that have more double bonds.
D) all of the choices

E) B) and C)
F) C) and D)

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Which of the following is considered a cardinal growth temperature?


A) the minimum temperature
B) the maximum temperature
C) the optimum temperature
D) All of these are considered cardinal growth temperatures.

E) C) and D)
F) B) and D)

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A common type of autoinducer found in gram-negative bacteria are acyl homoserine lactones (AHL).

A) True
B) False

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An open system in which the growth rate is maintained by adding a nutrient (present in limiting quantities) at the same rate that medium containing microorganisms is removed is called


A) manostat.
B) chemostat.
C) turbidostat.
D) culturostat.

E) A) and D)
F) A) and B)

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Which of the following can be used to estimate the number of microorganisms in a culture?


A) direct counts of microbial cells
B) counts of viable cells using colony growth procedures
C) measurements of microbial biomass
D) all of the choices

E) A) and D)
F) A) and C)

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