Portage Microbiology Exam #4 Questions
and Answers Graded A+
True or False: Growth media is best suited for distinguishing between two similar
species of bacteria - Correct answer-False. Growth media is designed to simply
support (and not restrict) microbial growth
What are the requirements of a fastidious microbe? (short answer) - Correct
answer-A fastidious microbe is an organism with complex growth requirements
such that is absent it will not grow. Enriched medias thus contain these specific and
essential nutrients required for the growth of a particular subset of microorganisms.
True or False: LB agar is classified as a selective, non-differential media - Correct
answer-False
What is agar used for in microbiology? (short answer) - Correct answer-Agar is
used to create a solid, smooth surface on which microbes can grow
Alpha hemolysis (matching) - Correct answer-Incomplete hemolytic activity
Beta hemolysis (matching) - Correct answer-Complete hemolytic activity
Gamma hemolysis (matching) - Correct answer-No hemolytic activity
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, Columbia CNA agar is most closely related to which media (multiple choice) -
Correct answer-CNA agar is similar to VAP as it is also enriched with blood and
allows for differentiation based on hemolytic patterns
True or False: Chocolate agar gets its brown color from cocoa to produce an
enriched media - Correct answer-False
In an attempt to detect the presence of the pathogenic strain of e coli O157:H7, a
researcher spread culture onto a MacConkey agar with failed results. What type of
agar should they (correctly) try next? Why? (short answer) - Correct answer-The
microbe should be plated on SMAC as it is specifically formulated to detect
O157:H7. Pathogenic e coli cannot ferment sorbitol while non-pathogenic e coli
can ferment both sorbitol and lactose. Therefore, colonies that ferment can be
differentiated from non-fermenters.
What is the gram status of microbes growing on eosin methylene blue agar plates?
(short answer) - Correct answer-Gram-negative
What is the process of spreading a bacterial culture onto a petri dish? (short
answer) - Correct answer-Plating
Mannitol salt agar will turn what color in the presence of the pathogenic strain
staphylococcus aureus? (short answer) - Correct answer-Yellow
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and Answers Graded A+
True or False: Growth media is best suited for distinguishing between two similar
species of bacteria - Correct answer-False. Growth media is designed to simply
support (and not restrict) microbial growth
What are the requirements of a fastidious microbe? (short answer) - Correct
answer-A fastidious microbe is an organism with complex growth requirements
such that is absent it will not grow. Enriched medias thus contain these specific and
essential nutrients required for the growth of a particular subset of microorganisms.
True or False: LB agar is classified as a selective, non-differential media - Correct
answer-False
What is agar used for in microbiology? (short answer) - Correct answer-Agar is
used to create a solid, smooth surface on which microbes can grow
Alpha hemolysis (matching) - Correct answer-Incomplete hemolytic activity
Beta hemolysis (matching) - Correct answer-Complete hemolytic activity
Gamma hemolysis (matching) - Correct answer-No hemolytic activity
©COPYRIGHT 2025, ALL RIGHTS RESERVED 1
, Columbia CNA agar is most closely related to which media (multiple choice) -
Correct answer-CNA agar is similar to VAP as it is also enriched with blood and
allows for differentiation based on hemolytic patterns
True or False: Chocolate agar gets its brown color from cocoa to produce an
enriched media - Correct answer-False
In an attempt to detect the presence of the pathogenic strain of e coli O157:H7, a
researcher spread culture onto a MacConkey agar with failed results. What type of
agar should they (correctly) try next? Why? (short answer) - Correct answer-The
microbe should be plated on SMAC as it is specifically formulated to detect
O157:H7. Pathogenic e coli cannot ferment sorbitol while non-pathogenic e coli
can ferment both sorbitol and lactose. Therefore, colonies that ferment can be
differentiated from non-fermenters.
What is the gram status of microbes growing on eosin methylene blue agar plates?
(short answer) - Correct answer-Gram-negative
What is the process of spreading a bacterial culture onto a petri dish? (short
answer) - Correct answer-Plating
Mannitol salt agar will turn what color in the presence of the pathogenic strain
staphylococcus aureus? (short answer) - Correct answer-Yellow
©COPYRIGHT 2025, ALL RIGHTS RESERVED 2
