PORTAGE LEARNING BIOD 171 EXAM
ANSWERS|LATEST !!!!2026|GRADED A+| (EXAM
True or False: Differential media is best suited for distinguishing between two similar species
of bacteria - 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? -
ANSWER Differential media
What are the requirements of a fastidious microbe? - ANSWER A fastidious microbe
is an organism with complex growth requirements such that if 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. -
ANSWER False.
The polysaccharide-based hardening agent added to LB media to produce LB agar is derived
from what? - ANSWER Seaweed (algae) extract.
1
, Blood agar is which type of medium? Select all that apply.
Selective
Enriched
Selective and Differential
Differential - 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
3. Gamma hemolysis C. Distinct zone of clearing - ANSWER 1. Alpha hemolysis --> B.
Greenish-brown color
2. Beta hemolysis ---> C. Distinct zone of clearing
3. Gamma hemolysis --> A. No change.
Columbia CNA agar is most closely related to which media: - ANSWER Blood agar
CNA agar is similar to BAP 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.
- ANSWER False
2
ANSWERS|LATEST !!!!2026|GRADED A+| (EXAM
True or False: Differential media is best suited for distinguishing between two similar species
of bacteria - 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? -
ANSWER Differential media
What are the requirements of a fastidious microbe? - ANSWER A fastidious microbe
is an organism with complex growth requirements such that if 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. -
ANSWER False.
The polysaccharide-based hardening agent added to LB media to produce LB agar is derived
from what? - ANSWER Seaweed (algae) extract.
1
, Blood agar is which type of medium? Select all that apply.
Selective
Enriched
Selective and Differential
Differential - 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
3. Gamma hemolysis C. Distinct zone of clearing - ANSWER 1. Alpha hemolysis --> B.
Greenish-brown color
2. Beta hemolysis ---> C. Distinct zone of clearing
3. Gamma hemolysis --> A. No change.
Columbia CNA agar is most closely related to which media: - ANSWER Blood agar
CNA agar is similar to BAP 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.
- ANSWER False
2
