BIOD 171 MODULE 4 ACTUAL EXAM
WITH VERIFIED CORRECT DETAILED
ANSWERS WITH RATIONALES
(VERIFIED ANSWERS)|GRADED A+
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What
... [Show More] is another name for a liquid growth media, and what are
the basic components? - correct answer-Growth media in a
liquid form is often referred to as nutrient broth. As the name
implies its composition consists primarily of essential
'ingredients' such as a rich source of sugars, amino acids, and
vitamins. Together, a nutrient broth provides the microbe with a
source of carbon/energy, which, in turn, encourages its
expansion.
What is selective media? - correct answer-Selective media
allows for only the growth of certain microbes while restricting
the growth of all others.
What is differential media? - correct answer-Differential media is
used to distinguish between two (or more) related microbes.
What are the requirements of a fastidious microbe? - correct
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.
What is agar? - correct answer-In its simplest form agar is liquid
growth media that has had a hardening agent added to it. Agar
is created when a polysaccharide derived from seaweed (algae)
extract is added to growth media. Agar is used to create a solid,
smooth surface on which microbes can grow.
LB agar is classified as a non-selective, differential media
True
False - correct answer-False
LB agar is non-selective and non-differential
What are the three forms of hemolysis found on blood agar
plates? - correct answer-Alpha hemolysis, beta hemolysis, and
gamma hemolysis
Alpha hemolysis - correct answer-Presents with greenish-brown
color on blood agar due to the partial lysis of red blood cells
Beta hemolysis - correct answer-Clear zones on blood agar
indicate beta hemolysis, which is the complete lysis of red blood
cells
Gamma hemolysis - correct answer-Presents a white/tan on
blood agar due to the lack of hemolytic activity.
What is the primary purpose of Columbia CNA agar? - correct
answer-As it suppresses the growth of Gram-negative bacteria
CNA agar is, therefore, used for isolation of Gram-positive
microbes.
Name the type of plate derived from BAP that contains lysed red
blood cells - correct answer-Lysed red blood cells (RBCs) are a
primary component in the formulation of Chocolate agar.
Define the selective and differential abilities of a MacConkey
agar plate - correct answer-MacConkey agar is selective in that
only Gram-negative microbes will grow on the agar -Gram-
positive microbes simply do not grow. MacConkey agar is also
considered a differential media as it distinguishes between
microbes capable of fermenting lactose (red colonies) and those
that are non-fermenters (white/tan colonies).
What colors would you expect to see on an EMB plate
containing E. coli? - correct answer-The EMB plate itself is red
in color while in the presence of E. coli, the growing colonies will
take on a distinctive metallic green sheen.
What is the name of the process of spreading a bacterial culture
onto a petri dish? - correct answer-Plating. Plating microbes can
be done using a sterile loop, a sterile swab, or a sterilized wire
loop. Each device is simply a means of spreading the bacteria,
most commonly in a simple back-and-forth motion, across the
plate.
What is the primary advantage of pla [Show Less]