PORTAGE LATEST
MICROBIOLOGY
EXAM #4
True or False: the purpose of a quadrant streak expand a bacterial
population - ANSWERS-False
To be considered a pure culture, the sample can be traced back to a
single cell and _________ - ANSWERS-The culture must also be free
from external contaminants. Would not contain multiple bacterial
species
When performing a quadrants streak, the sample is spread across the
plate in such as way as to form what? (short answer) - ANSWERS-A
dilution gradient is formed. The resulting gradient should always contain
within it the growth of individual colonies
In what phase of a dilution streak would you expect to find the lowest
concentration of bacteria, P2 or P4? (short answer) - ANSWERS-P4,
phases rank from highest to lowest
True or False: when performing a dilution streak a new loop must be
used for each phase - ANSWERS-True
END OF
PAGE 1
, PORTAGE LATEST
MICROBIOLOGY
EXAM #4
In order to encourage growth of a slow growing microbe what might a
researcher do during a phase dilution streak? (short answer) -
ANSWERS-A researcher may either opt to perform only a 3-phase
dilution streak or pass the loop through the previous phase multiple
times
True or False: to restrict the growth of a pathogenic researcher might
decrease an incubator from 37C to 25C - ANSWERS-True
When given an unknown bacterial sample the first step is to expand the
current bacterial population. Which form of media best suits this need?
Why? - ANSWERS-LB media. All the other options are all forms of
selective media, meaning they may potentially inhibit the growth of the
unknown sample. The culture should be first expanded and then placed
onto selective/differential plates
True or False: Differential media is best suited for distinguishing
between two similar species of bacteria - ANSWERS-True
True or False: Growth media is best suited for distinguishing between
two similar species of bacteria - ANSWERS-False. Growth media is
designed to simply support (and not restrict) microbial growth
END OF
PAGE 2
MICROBIOLOGY
EXAM #4
True or False: the purpose of a quadrant streak expand a bacterial
population - ANSWERS-False
To be considered a pure culture, the sample can be traced back to a
single cell and _________ - ANSWERS-The culture must also be free
from external contaminants. Would not contain multiple bacterial
species
When performing a quadrants streak, the sample is spread across the
plate in such as way as to form what? (short answer) - ANSWERS-A
dilution gradient is formed. The resulting gradient should always contain
within it the growth of individual colonies
In what phase of a dilution streak would you expect to find the lowest
concentration of bacteria, P2 or P4? (short answer) - ANSWERS-P4,
phases rank from highest to lowest
True or False: when performing a dilution streak a new loop must be
used for each phase - ANSWERS-True
END OF
PAGE 1
, PORTAGE LATEST
MICROBIOLOGY
EXAM #4
In order to encourage growth of a slow growing microbe what might a
researcher do during a phase dilution streak? (short answer) -
ANSWERS-A researcher may either opt to perform only a 3-phase
dilution streak or pass the loop through the previous phase multiple
times
True or False: to restrict the growth of a pathogenic researcher might
decrease an incubator from 37C to 25C - ANSWERS-True
When given an unknown bacterial sample the first step is to expand the
current bacterial population. Which form of media best suits this need?
Why? - ANSWERS-LB media. All the other options are all forms of
selective media, meaning they may potentially inhibit the growth of the
unknown sample. The culture should be first expanded and then placed
onto selective/differential plates
True or False: Differential media is best suited for distinguishing
between two similar species of bacteria - ANSWERS-True
True or False: Growth media is best suited for distinguishing between
two similar species of bacteria - ANSWERS-False. Growth media is
designed to simply support (and not restrict) microbial growth
END OF
PAGE 2
