MICR 2132 Lab Final Exam Questions
and Answers
What is a mixed culture? - Answer-Microbial culture consisting of two or more species.
What is a pure culture? - Answer-Microbial culture containing only a single species.
what is the process (steps, techniques, procedures involved) of isolation? - Answer-aseptic technique,
quadrant streaking
what is a major purpose for isolating bacteria? - Answer-to obtain a pure culture
what is the definition of media (as it relates to microbiology)? - Answer-a substance used for growing
microbes; may be liquid (usually a broth) or solid (usually agar)
What is selective media? - Answer-media designed to enhance the isolation procedure by inhibiting
growth of some organisms while encouraging the growth of others
What is differential media? - Answer-Growth medium that contains an indicator (usually color) to detect
the presence or absence of a specific metabolic activity
, Can a media be both selective and differential? - Answer-yes; many types of selective media contain
indicators to expose differences between organisms
Which of the selective and differential plate media are designed to be used (not that this was necessarily
the focus in lab) for G+ selection/isolation? - Answer-PEA, CNA, BEA, MSA
Which of the selective and differential place media are designed to be used for G- rod
selection/isolation? - Answer-MAC, EMB, HEA, XLD
what is the purpose of using controls for any tests/media used in microbiology? - Answer-so that you
have something that you can compare your results to; to be able to tell what the differences are in an
inoculated and uninoculated control
What is defined media? - Answer-A growth medium in which the exact amount and chemical formula
(and thus identity) of each ingredient are known.
what is undefined media? - Answer-a medium in which at least one nutritional ingredient is of unknown
composition or amount. Media with any plant or animal extract.
what are inhibitors and their purpose? - Answer-makes the medium selective; designed to exploit
weaknesses in specific groups of organism and thus prevent or inhibit their growth, while allowing
others to grow; ex. sodium chloride
What are substrates and their purpose? - Answer-makes the medium differential; provide the organism
all the required components for growth and by including at least one substrate that only one organism
or group of organisms can utilize. ex. lactose
what are indicators and their purpose? - Answer-makes a desired or expected reaction visible; virtually
always included in differential media; frequently a dye that changed color as pH changes.
and Answers
What is a mixed culture? - Answer-Microbial culture consisting of two or more species.
What is a pure culture? - Answer-Microbial culture containing only a single species.
what is the process (steps, techniques, procedures involved) of isolation? - Answer-aseptic technique,
quadrant streaking
what is a major purpose for isolating bacteria? - Answer-to obtain a pure culture
what is the definition of media (as it relates to microbiology)? - Answer-a substance used for growing
microbes; may be liquid (usually a broth) or solid (usually agar)
What is selective media? - Answer-media designed to enhance the isolation procedure by inhibiting
growth of some organisms while encouraging the growth of others
What is differential media? - Answer-Growth medium that contains an indicator (usually color) to detect
the presence or absence of a specific metabolic activity
, Can a media be both selective and differential? - Answer-yes; many types of selective media contain
indicators to expose differences between organisms
Which of the selective and differential plate media are designed to be used (not that this was necessarily
the focus in lab) for G+ selection/isolation? - Answer-PEA, CNA, BEA, MSA
Which of the selective and differential place media are designed to be used for G- rod
selection/isolation? - Answer-MAC, EMB, HEA, XLD
what is the purpose of using controls for any tests/media used in microbiology? - Answer-so that you
have something that you can compare your results to; to be able to tell what the differences are in an
inoculated and uninoculated control
What is defined media? - Answer-A growth medium in which the exact amount and chemical formula
(and thus identity) of each ingredient are known.
what is undefined media? - Answer-a medium in which at least one nutritional ingredient is of unknown
composition or amount. Media with any plant or animal extract.
what are inhibitors and their purpose? - Answer-makes the medium selective; designed to exploit
weaknesses in specific groups of organism and thus prevent or inhibit their growth, while allowing
others to grow; ex. sodium chloride
What are substrates and their purpose? - Answer-makes the medium differential; provide the organism
all the required components for growth and by including at least one substrate that only one organism
or group of organisms can utilize. ex. lactose
what are indicators and their purpose? - Answer-makes a desired or expected reaction visible; virtually
always included in differential media; frequently a dye that changed color as pH changes.
