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FINAL Mastering Questions (4-6)

Terms in this set (71)

Microbes have very narrow optimum temperature ranges. Which of the following classifications of microbes are most likely to cause human disease, based on their temperature requirements?
thermophiles
mesophiles
hyperthermophiles
psychrophiles
mesophiles
Bacteria that can grow in the presence or absence of oxygen (O2) are called __________.
obligate anaerobes
obligate aerobes
facultative anaerobes
microaerophiles
facultative anaerobes
Which of the following statements regarding infections involving biofilms is FALSE?
A)Microbes in biofilms are more resistant to antimicrobials than are independent organisms.
B)It is estimated that nearly 70% of all infections are caused by biofilms.
C)There is no way to prevent biofilms from developing on surfaces.
D)The majority of hospital-acquired infections (nosocomial infections) are related to biofilms.
C)There is no way to prevent biofilms from developing on surfaces.
For which of the following types of microbes would a microbiologist employ living host cells to support their growth?
A)normal skin bacteria
B)obligate intracellular organisms, such as chlamydia and viruses
C)capnophiles
D)Campylobacteria sp.
B)obligate intracellular organisms, such as chlamydia and viruses
A microbe reproduces by binary fission every 20 minutes under favorable conditions. If you started with one cell, how long would 10 generations take and how many bacteria would be present if all the conditions were just right?
A)24 hours, producing 262,144 bacteria
B)18 hours and 40 minutes, producing 1 million bacteria
C)2 hours and 10 minutes, producing 1,048,576 bacteria
D)3 hours 20 minutes, producing 1,024 bacteria
D)3 hours 20 minutes, producing 1,024 bacteria
Which of the following phases of the bacterial growth curve is matched with the correct definition?
A)lag phase--the phase in which the death of organisms exceeds the creation of new cells and the curve declines
B)death phase--the phase in which the curve is flat; microbial deaths balance the number of new cells
C)log phase--the phase in which organisms are actively dividing and the generation time is constant
D)stationary phase--the phase in which cells are not dividing very rapidly as they acclimatize to a new environment
C)log phase--the phase in which organisms are actively dividing and the generation time is constant
Which of the following methods used to count microbes is correctly identified as direct or indirect?
A)filtration--direct method
B)turbidity--direct method
C)dry weight--direct measurement
D)plate count--indirect measurement
A)filtration--direct method
What results when a single bacterium reproduces?
A)One parent cell and a genetically identical daughter cell
B)One parent cell and a genetically different cell
C)Two genetically identical daughter cells
D)Two genetically unique daughter cells
C)Two genetically identical daughter cells
If you begin with six cells, how many cells would you have after three rounds of division?
Twelve cells
Nine cells
Eighteen cells
Twenty-four cells
Forty-eight cells
It is impossible to determine.
Forty-eight cells
Which of the following is NOT a step in bacterial cell division?
A)Replication of the genetic material
B)Disappearance of nuclear envelope
C)Cell elongation
D)Splitting apart of two new daughter cells
B)Disappearance of nuclear envelope
Which step of binary fission is the reason for genetically identical daughter cells?
A)There are four new daughter cells that result from one parental cell
B)Splitting of the two daughter cells
C)Replication of the bacterial chromosome
D)Elongation of the cell
C)Replication of the bacterial chromosome
When microbial control methods are used, microbes are destroyed at a constant rate; there is no instantaneous death of all the microbes present. That microbial death rate is influenced by all of the following factors EXCEPT __________.
A)toxins produced by the microbe
B)the microbial characteristics
C)the time of exposure
D)the number of microbes
A)toxins produced by the microbe
Microbial control methods usually target any of the following microbial structures EXCEPT which one?
A)mitochondria
B)plasma membrane permeability
C)microbial proteins
D)nucleic acids
A) mitochondria
Which of the following physical methods of microbial control denatures proteins as a mechanism of action?
osmotic pressure
incineration
radiation
boiling or autoclaving
boiling or autoclaving
Consider various effects of moist and dry heat to control microbial growth. Which of the following methods would best reduce microbes without altering the taste and chemical composition of beer?
hot-air sterilization
pasteurization
autoclaving
boiling
pasteurization
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