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MICROBIO EXAM 2 STUDY
GUIDE/QUESTIONS Questions with
Detailed Verified Answers
An organism that uses light energy to form ATP and can only grow on
organic carbon sources is called a ________ —Correct Answer:
photoheterotroph
What type of microbes must possess the enzyme superoxide dismutase?
—Correct Answer: obligate aerobes
what type of microorganisms would you find living near hot springs? —
Correct Answer: thermophiles
what happens if a cell is placed in a hypertonic solution? —Correct
Answer: water leaves the cell, causing it to shrink
which of the following is not a benefit to microbes living in a biofilm —
Correct Answer: more choices for reproductive mates, thus more genetic
diversity
which of the following describes the best way to collect a clinical specimen
from the skin? —Correct Answer: brush a sterile swab across the skin,
being careful not to contact other areas
what is the purpose of performing the streak-plate technique —Correct
Answer: to obtain isolated colonies of bacteria
what must be done to a sample before performing the pour-plate
technique? —Correct Answer: colony-forming units must be separated by
performing serial dilutions
what is the best method for storing bacterial cultures for short periods of
time —Correct Answer: refrigeration
what is the best method of preservation to use if you want to preserve a
bacterial culture for 10 years or longer —Correct Answer: lyophilization
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what is one disadvantage of complex media as compared with defined
media? —Correct Answer: the specific nutritional requirements of an
organism cannot be determined with complex media
what type of medium would you use to culture an obligate anaerobe? —
Correct Answer: reducing medium
how would you culture an organism that grows best in 5% CO2? —Correct
Answer: candle jar
what is binary fission? —Correct Answer: a process in which a cell grows
and divides to produce two new daughter cells
during which phase of microbial growth is DNA and protein synthesis
maximal? —Correct Answer: log phase
when culturing a population of bacterial cells, how can the stationary
phase be avoided? —Correct Answer: by the use of a chemostat
what are 3 examples of a direct method for measuring microbial growth?
—Correct Answer: microscopic counts, membrane filtration, viable plate
count
what is the best way to measure microbial growth if the population of
microbes in a sample is very small? —Correct Answer: membrane
filtration
what scientific instrument is used to measure the turbidity of a microbial
population —Correct Answer: spectrophotometer
what scientific device is useful for counting larger cells such as protozoa?
—Correct Answer: coulter counter
if an organism cannot be grown in culture, how can it be identified? —
Correct Answer: DNA testing
aerobic —Correct Answer: require oxygen for their basic survival, growth,
and the process of reproduction
-ex: bacillus
anaerobic —Correct Answer: don't require oxygen for growth
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-ex: e coli
photoautotrophs —Correct Answer: -use CO2 as a carbon source and
light energy to make their own food
chemoautotrophs —Correct Answer: -use CO2 as a carbon source but
catabolize organic and inorganic molecules for energy
photoheterotrophs —Correct Answer: -photosynthetic organisms that
acquire energy from light and acquire nutrients via catabolism of organic
compounds
chemoheterotrophs —Correct Answer: -use organic compounds for both
energy and carbon
organotrophs —Correct Answer: -acquire electrons for redox reactions
from organic sources
lithotrophs —Correct Answer: -acquire electrons from inorganic sources
obligate aerobes —Correct Answer: -require O2 molecules as the final
electron acceptor of their electron transport chains
obligate anaerobes —Correct Answer: -cannot tolerate O2 and must use
an electron acceptor other than O2
what are the 4 toxic forms of oxygen? —Correct Answer: -singlet oxygen
-superoxide radicals
-peroxide anion
-hydroxyl radicals
singlet oxygen —Correct Answer: -toxic form of oxygen, neutralized by
pigments called carotenoids
superoxide radical —Correct Answer: -toxic form of oxygen that is
detoxified by superoxide dismutase
hydroxyl radical —Correct Answer: -most reactive of the toxic forms of
oxygen
MICROBIO EXAM 2 STUDY
GUIDE/QUESTIONS Questions with
Detailed Verified Answers
An organism that uses light energy to form ATP and can only grow on
organic carbon sources is called a ________ —Correct Answer:
photoheterotroph
What type of microbes must possess the enzyme superoxide dismutase?
—Correct Answer: obligate aerobes
what type of microorganisms would you find living near hot springs? —
Correct Answer: thermophiles
what happens if a cell is placed in a hypertonic solution? —Correct
Answer: water leaves the cell, causing it to shrink
which of the following is not a benefit to microbes living in a biofilm —
Correct Answer: more choices for reproductive mates, thus more genetic
diversity
which of the following describes the best way to collect a clinical specimen
from the skin? —Correct Answer: brush a sterile swab across the skin,
being careful not to contact other areas
what is the purpose of performing the streak-plate technique —Correct
Answer: to obtain isolated colonies of bacteria
what must be done to a sample before performing the pour-plate
technique? —Correct Answer: colony-forming units must be separated by
performing serial dilutions
what is the best method for storing bacterial cultures for short periods of
time —Correct Answer: refrigeration
what is the best method of preservation to use if you want to preserve a
bacterial culture for 10 years or longer —Correct Answer: lyophilization
, Page | 2
what is one disadvantage of complex media as compared with defined
media? —Correct Answer: the specific nutritional requirements of an
organism cannot be determined with complex media
what type of medium would you use to culture an obligate anaerobe? —
Correct Answer: reducing medium
how would you culture an organism that grows best in 5% CO2? —Correct
Answer: candle jar
what is binary fission? —Correct Answer: a process in which a cell grows
and divides to produce two new daughter cells
during which phase of microbial growth is DNA and protein synthesis
maximal? —Correct Answer: log phase
when culturing a population of bacterial cells, how can the stationary
phase be avoided? —Correct Answer: by the use of a chemostat
what are 3 examples of a direct method for measuring microbial growth?
—Correct Answer: microscopic counts, membrane filtration, viable plate
count
what is the best way to measure microbial growth if the population of
microbes in a sample is very small? —Correct Answer: membrane
filtration
what scientific instrument is used to measure the turbidity of a microbial
population —Correct Answer: spectrophotometer
what scientific device is useful for counting larger cells such as protozoa?
—Correct Answer: coulter counter
if an organism cannot be grown in culture, how can it be identified? —
Correct Answer: DNA testing
aerobic —Correct Answer: require oxygen for their basic survival, growth,
and the process of reproduction
-ex: bacillus
anaerobic —Correct Answer: don't require oxygen for growth
, Page | 3
-ex: e coli
photoautotrophs —Correct Answer: -use CO2 as a carbon source and
light energy to make their own food
chemoautotrophs —Correct Answer: -use CO2 as a carbon source but
catabolize organic and inorganic molecules for energy
photoheterotrophs —Correct Answer: -photosynthetic organisms that
acquire energy from light and acquire nutrients via catabolism of organic
compounds
chemoheterotrophs —Correct Answer: -use organic compounds for both
energy and carbon
organotrophs —Correct Answer: -acquire electrons for redox reactions
from organic sources
lithotrophs —Correct Answer: -acquire electrons from inorganic sources
obligate aerobes —Correct Answer: -require O2 molecules as the final
electron acceptor of their electron transport chains
obligate anaerobes —Correct Answer: -cannot tolerate O2 and must use
an electron acceptor other than O2
what are the 4 toxic forms of oxygen? —Correct Answer: -singlet oxygen
-superoxide radicals
-peroxide anion
-hydroxyl radicals
singlet oxygen —Correct Answer: -toxic form of oxygen, neutralized by
pigments called carotenoids
superoxide radical —Correct Answer: -toxic form of oxygen that is
detoxified by superoxide dismutase
hydroxyl radical —Correct Answer: -most reactive of the toxic forms of
oxygen
