BIOD 171 ESSENTIAL MICROBIOLOGY PORTAGE LEARNING
MODULE M4: MODULE 4 LATEST 2025/2026 EXAM - REQUIRES
RESPONDUS LOCKDOWN BROWSER + WEBCAM A+ SCORE
SOLUTION
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).
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
What are the requirements of a fastidious microbe?
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.
False.
The polysaccharide-based hardening agent added to LB media to
produce LB agar is derived from what?
Seaweed (algae) extract.
Blood agar is which type of medium? Select all that apply.
Selective
Enriched
Selective and Differential
Differential
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
1. Alpha hemolysis --> B. Greenish-brown color
MODULE M4: MODULE 4 LATEST 2025/2026 EXAM - REQUIRES
RESPONDUS LOCKDOWN BROWSER + WEBCAM A+ SCORE
SOLUTION
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).
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
What are the requirements of a fastidious microbe?
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.
False.
The polysaccharide-based hardening agent added to LB media to
produce LB agar is derived from what?
Seaweed (algae) extract.
Blood agar is which type of medium? Select all that apply.
Selective
Enriched
Selective and Differential
Differential
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
1. Alpha hemolysis --> B. Greenish-brown color
