BIOD 171 MODULE 4 Verified Questions And
Answers
T/F: Growth media is best suited for distinguishing between two similar species of bacteria ANS False
growth media is designed to simply support (and not restrict) microbial growth
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? ANS Differential media
What are the requirements of a fastidious microbe? ANS A fastidious microbe is an organism with
complex growth requirements and will not grow without then. Enriched medias thus contain these specific and
essential nutrients required for the growth of a particular subset of microorganisms.
T/F: LB agar is classified as a non-selective, non-differential media ANS True
The polysaccharide-based hardening agent added to LB media to produce LB agar is derived from what? ANS
Seaweed extract
Blood agar is which type of medium? Select all that apply:
- Selective and Differential
- Enriched
- Differential
- Selective ANS - Enriched
- Differential
Match the following hemolytic class with its description of activity:
1. Alpha hemolysis
2. Beta hemolysis
3. Gamma hemolysis
, A. No change
B. Greenish-brown color
C. Distinct zone of clearing ANS 1. Alpha hemolysis- Greenish-brown color (B)
2. Beta hemolysis- Distinct zone of clearing (C)
3. Gamma hemolysis- No change (A)
Match the following hemolytic class with its description of activity:
1. Alpha hemolysis
2. Beta hemolysis
3. Gamma hemolysis
A. No hemolytic activity
B. Incomplete hemolytic activity
C. Complete hemolytic activity ANS 1. Alpha hemolysis- Incomplete hemolytic activity (B)
2. Beta hemolysis- Complete hemolytic activity (C)
3. Gamma hemolysis- No hemolytic activity (A)
Columbia CNA agar is most closely related to which media: ANS Blood agar
CNA agar is similar to BAP as its also enriched with blood and allows for differentiation based on hemolytic
patterns
T/F: Chocolate agar gets its brown color from cocoa to produce an enriched media ANS False
chocolate is never added to the media. the name is derived simply based on the color that actually comes from
the presence of 'cooked' (lysed) red blood cells in the media
A researcher is studying a strain of E. coli currently growing on a MacConkey plate. However, the researcher
can't remember if E. coli is Gram-positive or Gram-negative. Would a Gram stain be necessary to confirm?
Why or why not? ANS No, because gram negative microbes only grow on macConkey agar
Answers
T/F: Growth media is best suited for distinguishing between two similar species of bacteria ANS False
growth media is designed to simply support (and not restrict) microbial growth
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? ANS Differential media
What are the requirements of a fastidious microbe? ANS A fastidious microbe is an organism with
complex growth requirements and will not grow without then. Enriched medias thus contain these specific and
essential nutrients required for the growth of a particular subset of microorganisms.
T/F: LB agar is classified as a non-selective, non-differential media ANS True
The polysaccharide-based hardening agent added to LB media to produce LB agar is derived from what? ANS
Seaweed extract
Blood agar is which type of medium? Select all that apply:
- Selective and Differential
- Enriched
- Differential
- Selective ANS - Enriched
- Differential
Match the following hemolytic class with its description of activity:
1. Alpha hemolysis
2. Beta hemolysis
3. Gamma hemolysis
, A. No change
B. Greenish-brown color
C. Distinct zone of clearing ANS 1. Alpha hemolysis- Greenish-brown color (B)
2. Beta hemolysis- Distinct zone of clearing (C)
3. Gamma hemolysis- No change (A)
Match the following hemolytic class with its description of activity:
1. Alpha hemolysis
2. Beta hemolysis
3. Gamma hemolysis
A. No hemolytic activity
B. Incomplete hemolytic activity
C. Complete hemolytic activity ANS 1. Alpha hemolysis- Incomplete hemolytic activity (B)
2. Beta hemolysis- Complete hemolytic activity (C)
3. Gamma hemolysis- No hemolytic activity (A)
Columbia CNA agar is most closely related to which media: ANS Blood agar
CNA agar is similar to BAP as its also enriched with blood and allows for differentiation based on hemolytic
patterns
T/F: Chocolate agar gets its brown color from cocoa to produce an enriched media ANS False
chocolate is never added to the media. the name is derived simply based on the color that actually comes from
the presence of 'cooked' (lysed) red blood cells in the media
A researcher is studying a strain of E. coli currently growing on a MacConkey plate. However, the researcher
can't remember if E. coli is Gram-positive or Gram-negative. Would a Gram stain be necessary to confirm?
Why or why not? ANS No, because gram negative microbes only grow on macConkey agar
