Page 1 of 9 Exam 4 Portage Learning BIOD 171 Exam 4 Portage Learning BIOD 171.pdf
1. True or False: Differential media is best suited for distinguishing
between two similar species of bacteria.
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)
2. 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?
Differential media
3. What are the requirements of a fastidious microbe?
The requirements of a fastidious microbe are that they have
complex growth requirements and if they are absent they
wont grow. So the Medius have the specific nutrients that
will promote the growth of this specific microorganism.
4. True or False: LB agar is classified as a selective, non-differential
media.
False: LB agar is the most basic type of agar and like LB media
supports the growth of virtually all microbes without restriction
5. What is agar used for in microbiology?
Agar is used as a, smooth surface where microbes can be
grown.
6. The polysaccharide-based hardening agent added to LB media to
produce LB agar is derived from what?
seaweed (algae)
7. Blood agar is which type of medium? Select all that apply.
Differential
Blood agar can be used to differential between species based on its
hemolytic activity.
Enriched
Blood agar can be used to differential between species based on its
hemolytic activity.
This study source was downloaded by 1827175 from cliffsnotes.com on 01-08-2026 18:43:03 GMT -06:00
Exam 4 Portage Learning BIOD 171 Page 1 of 9 Exam 4 Portage Learning BIOD 171.pdf
https://www.cliffsnotes.com//study-notes/23140061
, Page 2 of 9 Exam 4 Portage Learning BIOD 171 Exam 4 Portage Learning BIOD 171.pdf
8. Match the following hemolytic class with its description of activity.
I. Alpha hemolysis - B. Greenish-brown
II. Beta hemolysis color - C. Distinct zone of
III. Gamma hemolysis clearing - A. No change
9. Columbia CNA agar is used to isolate:
Gram-Positive
CNA agar restricts Gram-Negative microbes therefore only GramPositive
microbes will grow.
10. True or False: Chocolate (cocoa) is not a component of Chocolate
agar plates
True : The name is derived simply based on the color that actually
comes from the presence of ‘cooked’ (lysed) red blood cells in the
media.
11. True or False: Chocolate agar gets its brown color from cocoa to
produce an enriched media
False: Chocolate (cocoa) 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.
12. An unknown microbe is streaked onto a MacConkey agar plate.
After an overnight incubation at 37°C, growth is observed. Would a
Gram stain be necessary? Why or why not?
No, a Gram stain will not be necessary because MacConkey
agar only allows the growth of Gram-negative bacteria;
which means the microbe will be a Gram-negative microbe
13. 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?
No. A Gram stain would not be necessary, as only Gram-
Negative microbes will grow on MacConkey agar. Thus, E.
coli is a Gram-Negative microbe.
14. In an attempt to detect the presence of the pathogenic strain of
E. coli O157:H7, a researcher spread a culture onto a MacConkey
This study source was downloaded by 1827175 from cliffsnotes.com on 01-08-2026 18:43:03 GMT -06:00
Exam 4 Portage Learning BIOD 171 Page 2 of 9 Exam 4 Portage Learning BIOD 171.pdf
https://www.cliffsnotes.com//study-notes/23140061
1. True or False: Differential media is best suited for distinguishing
between two similar species of bacteria.
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)
2. 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?
Differential media
3. What are the requirements of a fastidious microbe?
The requirements of a fastidious microbe are that they have
complex growth requirements and if they are absent they
wont grow. So the Medius have the specific nutrients that
will promote the growth of this specific microorganism.
4. True or False: LB agar is classified as a selective, non-differential
media.
False: LB agar is the most basic type of agar and like LB media
supports the growth of virtually all microbes without restriction
5. What is agar used for in microbiology?
Agar is used as a, smooth surface where microbes can be
grown.
6. The polysaccharide-based hardening agent added to LB media to
produce LB agar is derived from what?
seaweed (algae)
7. Blood agar is which type of medium? Select all that apply.
Differential
Blood agar can be used to differential between species based on its
hemolytic activity.
Enriched
Blood agar can be used to differential between species based on its
hemolytic activity.
This study source was downloaded by 1827175 from cliffsnotes.com on 01-08-2026 18:43:03 GMT -06:00
Exam 4 Portage Learning BIOD 171 Page 1 of 9 Exam 4 Portage Learning BIOD 171.pdf
https://www.cliffsnotes.com//study-notes/23140061
, Page 2 of 9 Exam 4 Portage Learning BIOD 171 Exam 4 Portage Learning BIOD 171.pdf
8. Match the following hemolytic class with its description of activity.
I. Alpha hemolysis - B. Greenish-brown
II. Beta hemolysis color - C. Distinct zone of
III. Gamma hemolysis clearing - A. No change
9. Columbia CNA agar is used to isolate:
Gram-Positive
CNA agar restricts Gram-Negative microbes therefore only GramPositive
microbes will grow.
10. True or False: Chocolate (cocoa) is not a component of Chocolate
agar plates
True : The name is derived simply based on the color that actually
comes from the presence of ‘cooked’ (lysed) red blood cells in the
media.
11. True or False: Chocolate agar gets its brown color from cocoa to
produce an enriched media
False: Chocolate (cocoa) 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.
12. An unknown microbe is streaked onto a MacConkey agar plate.
After an overnight incubation at 37°C, growth is observed. Would a
Gram stain be necessary? Why or why not?
No, a Gram stain will not be necessary because MacConkey
agar only allows the growth of Gram-negative bacteria;
which means the microbe will be a Gram-negative microbe
13. 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?
No. A Gram stain would not be necessary, as only Gram-
Negative microbes will grow on MacConkey agar. Thus, E.
coli is a Gram-Negative microbe.
14. In an attempt to detect the presence of the pathogenic strain of
E. coli O157:H7, a researcher spread a culture onto a MacConkey
This study source was downloaded by 1827175 from cliffsnotes.com on 01-08-2026 18:43:03 GMT -06:00
Exam 4 Portage Learning BIOD 171 Page 2 of 9 Exam 4 Portage Learning BIOD 171.pdf
https://www.cliffsnotes.com//study-notes/23140061
