PORTAGE MICROBIOLOGY EXAM 3
GRADED A STUDY GUIDE QUESTIONS AND
SOLUTIONS 2026 CORRECT ANSWERS
GRADED A+
⩥ A researcher is asked to determine which of two vials contains e coli
and which contains salmonella. Knowing both gram-negative while only
one of them is capable of fermenting lactose, which type of media would
be best suited (multiple choice). Answer: Differential media
distinguishes between two, often related, microbes
⩥ A researcher is asked to determine if a sample contains Neisseria
meningitides. Knowing Neisseria meningitides is slow growing and
other foreign microbes may also be present in the culture, which type of
media would be best suited? (multiple choice). Answer: Selective media
⩥ What are the requirements of a fastidious microbe? (short answer).
Answer: A fastidious microbe is an organism with complex growth
requirements such that is 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
, ⩥ What is agar used for in microbiology? (short answer). Answer: Agar
is used to create a solid, smooth surface on which microbes can grow
⩥ Alpha hemolysis (matching). Answer: Incomplete hemolytic activity
⩥ Beta hemolysis (matching). Answer: Complete hemolytic activity
⩥ Gamma hemolysis (matching). Answer: No hemolytic activity
⩥ Columbia CNA agar is most closely related to which media (multiple
choice). Answer: Blood agar
⩥ True or False: Chocolate agar gets its brown color from cocoa to
produce an enriched media. Answer: False
⩥ True or False: Chocolate is not a component of chocolate agar plates.
Answer: True
⩥ 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? (short answer). Answer: No. A gram stain
would not be necessary, as only gram negative microbes will grown on
MacConkey agar. Thus, e coli is a gram negative microbe
GRADED A STUDY GUIDE QUESTIONS AND
SOLUTIONS 2026 CORRECT ANSWERS
GRADED A+
⩥ A researcher is asked to determine which of two vials contains e coli
and which contains salmonella. Knowing both gram-negative while only
one of them is capable of fermenting lactose, which type of media would
be best suited (multiple choice). Answer: Differential media
distinguishes between two, often related, microbes
⩥ A researcher is asked to determine if a sample contains Neisseria
meningitides. Knowing Neisseria meningitides is slow growing and
other foreign microbes may also be present in the culture, which type of
media would be best suited? (multiple choice). Answer: Selective media
⩥ What are the requirements of a fastidious microbe? (short answer).
Answer: A fastidious microbe is an organism with complex growth
requirements such that is 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
, ⩥ What is agar used for in microbiology? (short answer). Answer: Agar
is used to create a solid, smooth surface on which microbes can grow
⩥ Alpha hemolysis (matching). Answer: Incomplete hemolytic activity
⩥ Beta hemolysis (matching). Answer: Complete hemolytic activity
⩥ Gamma hemolysis (matching). Answer: No hemolytic activity
⩥ Columbia CNA agar is most closely related to which media (multiple
choice). Answer: Blood agar
⩥ True or False: Chocolate agar gets its brown color from cocoa to
produce an enriched media. Answer: False
⩥ True or False: Chocolate is not a component of chocolate agar plates.
Answer: True
⩥ 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? (short answer). Answer: No. A gram stain
would not be necessary, as only gram negative microbes will grown on
MacConkey agar. Thus, e coli is a gram negative microbe
