Portage Learning Microbiology BIOD 171 module 4 Questions and Answers
Growth media in a liquid form is often
referred to as nutrient broth. As the name
implies its composition consists primarily
What is another name for a liquid growth of essential 'ingredients' such as a rich
media, and what are the basic compo- source of sugars, amino acids, and vita-
nents? mins. Together, a nutrient broth provides
the microbe with a source of carbon/en-
ergy, which, in turn, encourages its ex-
pansion.
Selective media allows for only the
What is selective media? growth of certain microbes while restrict-
ing the growth of all others.
Differential media is used to distinguish
What is differential media?
between two (or more) related microbes.
A fastidious microbe is an organism with
complex growth requirements such that
What are the requirements of a fastidi- if absent it will not grow. Enriched medias
ous microbe? thus contain these specific and essential
nutrients required for the growth of a par-
ticular subset of microorganisms.
In its simplest form agar is liquid growth
media that has had a hardening agent
added to it. Agar is created when a poly-
What is agar? saccharide derived from seaweed (al-
gae) 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,
False
differential media
LB agar is non-selective and non-differ-
True
ential
False
What are the three forms of hemolysis Alpha hemolysis, beta hemolysis, and
found on blood agar plates? gamma hemolysis
Alpha hemolysis
1/8
, Portage Learning Microbiology BIOD 171 module 4 Questions and Answers
Presents with greenish-brown color on
blood agar due to the partial lysis of red
blood cells
Clear zones on blood agar indicate beta
Beta hemolysis hemolysis, which is the complete lysis of
red blood cells
Presents a white/tan on blood agar due
Gamma hemolysis
to the lack of hemolytic activity.
As it suppresses the growth of
What is the primary purpose of Columbia Gram-negative bacteria CNA agar is,
CNA agar? therefore, used for isolation of Gram-pos-
itive microbes.
Lysed red blood cells (RBCs) are a pri-
Name the type of plate derived from BAP
mary component in the formulation of
that contains lysed red blood cells
Chocolate agar.
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 con-
Define the selective and differential abil-
sidered a differential media as it distin-
ities of a MacConkey agar plate
guishes between microbes capable of
fermenting lactose (red colonies) and
those that are non-fermenters (white/tan
colonies).
The EMB plate itself is red in color while
What colors would you expect to see on in the presence of E. coli, the growing
an EMB plate containing E. coli? colonies will take on a distinctive metallic
green sheen.
Plating. Plating microbes can be done
using a sterile loop, a sterile swab, or a
What is the name of the process of
sterilized wire loop. Each device is simply
spreading a bacterial culture onto a petri
a means of spreading the bacteria, most
dish?
commonly in a simple back-and-forth
motion, across the plate.
The primary advantage of plating a bac-
terial sample onto agar is that cells are
2/8
Growth media in a liquid form is often
referred to as nutrient broth. As the name
implies its composition consists primarily
What is another name for a liquid growth of essential 'ingredients' such as a rich
media, and what are the basic compo- source of sugars, amino acids, and vita-
nents? mins. Together, a nutrient broth provides
the microbe with a source of carbon/en-
ergy, which, in turn, encourages its ex-
pansion.
Selective media allows for only the
What is selective media? growth of certain microbes while restrict-
ing the growth of all others.
Differential media is used to distinguish
What is differential media?
between two (or more) related microbes.
A fastidious microbe is an organism with
complex growth requirements such that
What are the requirements of a fastidi- if absent it will not grow. Enriched medias
ous microbe? thus contain these specific and essential
nutrients required for the growth of a par-
ticular subset of microorganisms.
In its simplest form agar is liquid growth
media that has had a hardening agent
added to it. Agar is created when a poly-
What is agar? saccharide derived from seaweed (al-
gae) 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,
False
differential media
LB agar is non-selective and non-differ-
True
ential
False
What are the three forms of hemolysis Alpha hemolysis, beta hemolysis, and
found on blood agar plates? gamma hemolysis
Alpha hemolysis
1/8
, Portage Learning Microbiology BIOD 171 module 4 Questions and Answers
Presents with greenish-brown color on
blood agar due to the partial lysis of red
blood cells
Clear zones on blood agar indicate beta
Beta hemolysis hemolysis, which is the complete lysis of
red blood cells
Presents a white/tan on blood agar due
Gamma hemolysis
to the lack of hemolytic activity.
As it suppresses the growth of
What is the primary purpose of Columbia Gram-negative bacteria CNA agar is,
CNA agar? therefore, used for isolation of Gram-pos-
itive microbes.
Lysed red blood cells (RBCs) are a pri-
Name the type of plate derived from BAP
mary component in the formulation of
that contains lysed red blood cells
Chocolate agar.
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 con-
Define the selective and differential abil-
sidered a differential media as it distin-
ities of a MacConkey agar plate
guishes between microbes capable of
fermenting lactose (red colonies) and
those that are non-fermenters (white/tan
colonies).
The EMB plate itself is red in color while
What colors would you expect to see on in the presence of E. coli, the growing
an EMB plate containing E. coli? colonies will take on a distinctive metallic
green sheen.
Plating. Plating microbes can be done
using a sterile loop, a sterile swab, or a
What is the name of the process of
sterilized wire loop. Each device is simply
spreading a bacterial culture onto a petri
a means of spreading the bacteria, most
dish?
commonly in a simple back-and-forth
motion, across the plate.
The primary advantage of plating a bac-
terial sample onto agar is that cells are
2/8
