Home
M4: Module 4 Exam- Requires Respondus LockDown Submission Details:
Module Browser Time: 59 minutes
s
Due No due date Points 100 Questions 24 Time Limit 60 Minutes
Grades Requires Respondus LockDown Curren 89 out of
Browser
t 100
Score:
This quiz is currently 89 out of
locked. Kept Score:
100
Attempt History
Attempt Time Score
LATEST Attempt 1 59 minutes 89 out of 100
Score for this quiz: 89 out of
100 Submitted Dec 9, 2020 at
1:52pm This attempt took 59
minutes.
Question 1 pts
True or False: Differential media is best suited for distinguishing between two similar species of
bacteria.
Correct!
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).
==
False
Question 2 pts
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?
Correct!
Selective media
Selective media. If additional foreign microbes may be present in your sample and you know Neisseria
meningitides is slow growing, you must restrict the unwanted microbes while supporting the growth of
Neisseria meningitides. Thus, you are selectively encouraging one microbes growth, while selectively
restricting others.
Selective and Differential media
Differential media
Growth media
Question 3 pts
What are the requirements of a fastidious microbe?
Your Answer:
Essential nutrients for the growth of the microorganisms, they are organisms with abstract
growth requirements, without these requirements they will not grow.
Enriched Medias contains the specific and essential nutrients required for the growth of the
subset of these microorganisms. Medias can be any combination of selective, differential and
enriched.
--=
Question 4 pts
True or False: LB agar is classified as a selective, non-differential media.
True
Correct!
False
LB agar is the most basic type of agar and like LB media supports the growth of virtually all microbes
without restriction.
pts
Question 5
The polysaccharide-based hardening agent added to LB media to produce LB agar is derived
from what?
Your Answer:
It is derived from an algae, also known as seaweed and creates the solid medium called agar.
Seaweed (algae) extract.
Question 6 pts
Blood agar is which type of medium? Select all that apply.
Correct!
Differential
Blood agar can be used to differential between species based on its hemolytic activity.
Selective
Correct Answer
Enriched
Selective and Differential
Question 7 pts
Match the following hemolytic class with its description of activity.
Columbia CNA agar is most closely related to which media:
EMB agar
Trypticase Soy Agar
Correct!
Blood agar
CNA agar is similar to BAP as it is also enriched with blood and allows for differentiation based on
hemolytic patterns.
MacConkey Agar
Question 9 pts
True or False: Chocolate agar gets its brown color from cocoa to produce an enriched media.
True
Correct! 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.
pts
Question 10
An unknown microbe is streaked onto a MacConkey agar plate. A$er an overnight incubation at
37°C, growth is observed. Would a Gram stain be necessary? Why or why not?
Your Answer:
A gram stain would not be necessary as restricts gram-positive bacterial growth. If a growth
occured, we know that it is a gram negative microbe. The color of the base of the agar plate
changes as the microbes consume the nutrients within the agar.
Therefore, no gram stain would be necessary.
No. A Gram stain would not be necessary, as only Gram-Negative microbes will
grow on MacConkey agar.
pts
Question 11
In an attempt to detect the presence of the pathogenic strain of E. coli O157:H7, a researcher
spread a culture onto a MacConkey agar with failed results. What type of agar should
they (correctly) try next? Why?
Your Answer:
The pathogenic strain of E.coli 0157:H7 is different from the other E. Coli strains as it is
unable to ferment sorbitol. MacConkey plates contain sorbitol, instead of lactose to tell
the difference between non-pathogenic strains of E.coli and pathogenic. The researcher
should try an EMB plate next, or an Eosin Methylene Blue Agar next as it is similar to
the SMAC plate as lactose fermenting microbes will produce colonies on the surface of
the agar. If it is present, it will show as a metallic green color on the EMB agar plates.
The microbe should be plated on SMAC (Sorbitol-MacConkey agar) as it is specifically
formulated to detect O157:H7. Pathogenic E. coli (O157:H7) cannot ferment sorbitol
while non-pathogenic E. coli can ferment both soribitol and lactose. Therefore, colonies
that ferment (acidic conditions; non- pathogenic) can be differentiated from non-
fermenters (neutral to basic conditions; pathogenic).
Question 12 pts
What is the Gram status (positive or negative) of microbes growing on Eosin Methylene Blue
(EMB) agar plates?
Your Answer:
The Gram status of the microbes growing on Eosin Methylene Blue (EMB) agar plates are Gram
negative as it restricts the growth of Gram positive bacteria.
Gram-Negative. EMB plates specifically restrict the growth of Gram-Positive bacteria.
Question 13 pts
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller MiaWilliams88. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $11.49. You're not tied to anything after your purchase.
