BIOD 171 FINAL EXAM | ALL QUESTIONS
AND CORRECT ANSWERS WITH
EXPLANATIONS | ALREADY GRADED A+ |
VERIFIED ANSWERS | LATEST VERSION
When performing a quadrant streak, the sample is spread across the plate
in such a way to form what? ------CORRECT ANSWER---------------A dilution
gradient.
A dilution gradient is formed. The resulting gradient should always contain
within it the growth of individual colonies.
A dilution gradient is formed when carrying out what generalize plating
strategy? ------CORRECT ANSWER---------------Phase-Dilution streak
In what phase of dilution streak would you expect to find the lowest
concentration of bacteria. P2 or P4? ------CORRECT ANSWER---------------
P4.
The phases concentration rank from P1 being the highest, then P2, P3, and
P4.
P4 (Phase 4) would contain the lowest concentration of bacteria. The
phases rank (from highest to lowest), P1 > P2 > P3 > P4.
True or False. When performing a dilution streak a new (or sterilized) loop
is not required for each phase as long as the bacterial culture is pure. ------
CORRECT ANSWER---------------False
,True or False. When performing a dilution streak a new (or sterilized) loop
must be used for each phase. ------CORRECT ANSWER---------------True
Failure to do so would prevent the establishment of a dilution gradient, as
the same bacterial concentration would be spread across both phase
regions.
The number of phases (3 vs. 4) and/or the number of times a loop passes
through a previous phase (once vs. multiple) is acceptable provided what
happens? ------CORRECT ANSWER---------------The resulting gradient has
growth of the individual colonies in it.
Either deviation is acceptable in practice provided the resulting gradient
contains within it the growth of individual colonies—if not, the experiment
must be repeated.
True or False. To restrict the growth of a pathogenic microbe a researcher
might decrease an incubator from 37°C to 25°C. ------CORRECT
ANSWER---------------True
When given an unknown bacterial sample the first step is to expand the
current bacterial population. Which form of media best suites this need?
Why?
1. MSA agar
2. LB media
3. MacConkey agar
4. Columbia CNA agar ------CORRECT ANSWER---------------LB media. All
other options are forms of selective media which means they would
potentially inhibit the growth of the unknown sample.
LB media. All other options (A, C and D) are all forms of selective media,
meaning they may potentially inhibit the growth of the unknown sample.
The culture should be first expanded and then place onto
selective/differential agar plates.
, True or False. Only directly ingesting the pre-formed clostridium toxin
(neither the bacteria nor its spores) will cause disease in adults. ------
CORRECT ANSWER---------------True
True or False. There are currently no cures for tetanus. ------CORRECT
ANSWER---------------True
The alpha-toxin perfringolysin is associated with which medical condition
caused by Gram-positive anaerobic bacteria?
Tetanus
Leprosy
Botulism
Gas gangrene ------CORRECT ANSWER---------------Gas gangrene
True or False. Pneumonic plague is often characterized by painfully
swollen lymph nodes. ------CORRECT ANSWER---------------False
True or False. Bubonic plague is often characterized by painfully swollen
lymph nodes. ------CORRECT ANSWER---------------True
Identify the following disease: (image of hand with large black open sore on
base of thumb)
Gas gangrene
Frost bite
Anthrax
Tetanus ------CORRECT ANSWER---------------Anthrax
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