Portage Microbiology BIOD171 Exam 4
Questions and Answers Graded A+
True or False: Differential media is best suited for distinguishing between two
similar species of bacteria - Correct answer-True
Growth media does not contain restrictive factors, while selective media is best
used to encourage the growth of one microbe while simultaneously discouraging
the growth of the other. Since two similar species of microbes are being studied
they must be differentiated under similar but just slightly different conditions
(differential media).
A researcher is asked to determine which of two vials contains E coli and which
contains salmonella. Knowing both are Gram-negative while only one of them is
capable of fermenting lactose, which type of media would be best suited? - Correct
answer-Differential media
What are the requirements of a fastidious microbe? - Correct answer-A fastidious
microbe is an organism with complex growth requirements such that if absent it
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, 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.
The polysaccharide-based hardening agent added to LB media to produce LB agar
is derived from what? - Correct answer-Seaweed (algae) extract.
Blood agar is which type of medium? Select all that apply.
Selective
Enriched
Selective and Differential
Differential - Correct answer-Enriched
Differential
Match the following hemolytic class with its description of activity.
1. Alpha hemolysis A. No change.
2. Beta hemolysis B. Greenish-brown color
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Questions and Answers Graded A+
True or False: Differential media is best suited for distinguishing between two
similar species of bacteria - Correct answer-True
Growth media does not contain restrictive factors, while selective media is best
used to encourage the growth of one microbe while simultaneously discouraging
the growth of the other. Since two similar species of microbes are being studied
they must be differentiated under similar but just slightly different conditions
(differential media).
A researcher is asked to determine which of two vials contains E coli and which
contains salmonella. Knowing both are Gram-negative while only one of them is
capable of fermenting lactose, which type of media would be best suited? - Correct
answer-Differential media
What are the requirements of a fastidious microbe? - Correct answer-A fastidious
microbe is an organism with complex growth requirements such that if absent it
©COPYRIGHT 2025, ALL RIGHTS RESERVED 1
, 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.
The polysaccharide-based hardening agent added to LB media to produce LB agar
is derived from what? - Correct answer-Seaweed (algae) extract.
Blood agar is which type of medium? Select all that apply.
Selective
Enriched
Selective and Differential
Differential - Correct answer-Enriched
Differential
Match the following hemolytic class with its description of activity.
1. Alpha hemolysis A. No change.
2. Beta hemolysis B. Greenish-brown color
©COPYRIGHT 2025, ALL RIGHTS RESERVED 2
