Question 1

When differentiating colony size on the culture plates, what organisms generally have the larger colonies by comparison?

Accepted Answer

A)   Gram-negative rods
B)   Gram-positive cocci
C)   Gram-negative diplococci
D)   Gram-positive rodsE) B) and D)
F) A) and B)

Question 2

Which of the following descriptions will directly facilitate identification of bacteria?

Accepted Answer

A)   Environmental growth temperature
B)   Physical characteristics of colony morphology
C)   Environmental growth atmosphere
D)   Colony colorE) B) and D)
F) A) and B)

Question 3

When microbiologists set up a biochemical identification using a commercial system on a suspected pathogen from a culture, they must

Accepted Answer

A)   recognize the colony characteristics of the pathogen.
B)   observe the culture after 18 to 24 hours of incubation.
C)   confirm identification with biochemical tube testing.
D)   correlate colony characteristics with the suspected identification of the organism.E) None of the above
F) All of the above

Question 4

A microbiologist is reading stool culture plates. She sees an organism that has a large, mucoid pink colony on MAC. What is a good presumptive identification of this organism?

Accepted Answer

A)   Enteric pathogen
B)   Escherichia/Citrobacter-like organism
C)   Klebsiella/Enterobacter-like organism
D)   Haemophilus influenzaeE) B) and D)
F) None of the above C

Question 5

Generally, microbiologists observe the colonial morphology of organisms on primary culture after how many hours of incubation?

Accepted Answer

A)   18 to 24 hours
B)   6 to 12 hours
C)   24 to 48 hours
D)   72 hoursE) A) and D)
F) C) and D)

Question 6

Gamma ( γ\gammaγ ) -hemolysis is

Accepted Answer

A)   complete clearing of erythrocytes in a BAP around and under the colony.
B)   partial lysing of erythrocytes in a BAP around and under the colony.
C)   when organisms have no lytic effect on the erythrocytes in the BAP.
D)   a pink "halo" around a colony. E) C) and D)
F) B) and D)

Question 7

The term used to describe colonies that are solid in color and that do not allow any light to pass through is

Accepted Answer

A)   opaque.
B)   transparent.
C)   translucent.
D)   ground glass.E) None of the above
F) C) and D)

Question 8

The colonies growing on the SBA have produced a wide, deep, clear zone around and under the colonies. This is consistent with which type of hemolysis?

Accepted Answer

A)   Alpha
B)   Beta
C)   Gamma (no hemolysis) 
D)   DeltaE) A) and C)
F) A) and B) C

Question 9

The density of the bacterial colony can be described by all the following, except

Accepted Answer

A)   transparent.
B)   translucent.
C)   opaque.
D)   ground glass.E) All of the above
F) None of the above

Question 10

Colonies growing on the SBA have discolored the media to a green color around and under the colonies. This is consistent with which type of hemolysis?

Accepted Answer

A)   Alpha
B)   Beta
C)   Gamma (no hemolysis) 
D)   DeltaE) A) and B)
F) A) and C)

Question 11

A term used to describe colonies that resemble coins is

Accepted Answer

A)   umbonate.
B)   flat.
C)   umbilicate.
D)   raised.E) A) and D)
F) None of the above

Question 12

Swarming is

Accepted Answer

A)   many bacterial colonies crowded together at one place on the agar plate.
B)   when colonies on a BAP have a "halo" around the bacterial colony.
C)   when a bacterial colony on a BAP grows over the top of the erythrocytes it hemolyzed.
D)   a hazy blanket of growth on the surface of the agar that extends way beyond the streak lines.E) All of the above
F) C) and D)

Question 13

Alph ( β\betaβ ) -hemolysis is

Accepted Answer

A)   complete clearing of erythrocytes in a blood agar plate (BAP)  around and under the colony.
B)   partial lysing of erythrocytes in a BAP around and under the colony.
C)   when organisms have no lytic effect on the erythrocytes in the BAP.
D)   a pink "halo" around a colony. E) B) and C)
F) A) and D) B

Question 14

Beta ( β\betaβ  ) -hemolysis is

Accepted Answer

A)   complete clearing of erythrocytes in a BAP around and under the colony.
B)   partial lysing of erythrocytes in a BAP around and under the colony.
C)   when organisms have no lytic effect on the erythrocytes in the BAP.
D)   a pink "halo" around a colony. E) B) and C)
F) A) and C)

Question 15

When looking at a tube of thioglycollate broth, streamers or vines and puffballs are visible. What organism grows like this in thioglycollate?

Accepted Answer

A)   Gram-negative rods (Enterobacteriaceae) 
B)   Streptococcus spp.
C)   yeast
D)   Pseudomonas spp.E) All of the above
F) A) and B)

Question 16

All the following colors are commonly used to describe bacteria, except

Accepted Answer

A)   buff.
B)   white.
C)   orange.
D)   gray.E) All of the above
F) B) and C)

Question 17

Colonies of Bacillus anthracis are described as

Accepted Answer

A)   Curschmann's spiral.
B)   Mickey Mouse ears.
C)   Medusa's heads.
D)   flower like.E) All of the above
F) A) and D)

Question 18

Plate reading is

Accepted Answer

A)   examining the colonial morphology of bacteria.
B)   a comparative examination of bacteria growing on a variety of culture media.
C)   setting up biochemical tests to identify bacteria.
D)   determining if the inoculum is mixed.E) A) and B)
F) C) and D)

Question 19

A microbiologist is reading a vaginal culture. She sees the very white colonies that are non -hemolytic on a BAP but appear to have feet. What organism could this possibly be?

Accepted Answer

A)   Yeast
B)   Gram-positive cocci
C)   Gram-negative rods
D)   Haemophilus influenzaeE) B) and C)
F) C) and D)

Question 20

The relative concentration of bacteria on culture plates is directly proportional to

Accepted Answer

A)   the amount of nutrients in the culture plates.
B)   the environment in which the bacteria is grown.
C)   the concentration in which they are present in the clinical specimen.
D)   the amount of bacteria isolated from the initial inoculation on the plate.E) B) and D)
F) All of the above

Exam 8: Use of Colony Morphology for the Presumptive Identification of Microorganisms

When differentiating colony size on the culture plates, what organisms generally have the larger colonies by comparison?

Correct AnswerverifiedShow Answer

Which of the following descriptions will directly facilitate identification of bacteria?

Correct AnswerverifiedShow Answer

When microbiologists set up a biochemical identification using a commercial system on a suspected pathogen from a culture, they must

Correct AnswerverifiedShow Answer

A microbiologist is reading stool culture plates. She sees an organism that has a large, mucoid pink colony on MAC. What is a good presumptive identification of this organism?

Correct AnswerverifiedC

Generally, microbiologists observe the colonial morphology of organisms on primary culture after how many hours of incubation?

Correct AnswerverifiedShow Answer

Gamma ( γ\gammaγ ) -hemolysis is

Correct AnswerverifiedShow Answer

The term used to describe colonies that are solid in color and that do not allow any light to pass through is

Correct AnswerverifiedShow Answer

The colonies growing on the SBA have produced a wide, deep, clear zone around and under the colonies. This is consistent with which type of hemolysis?

Correct AnswerverifiedC

The density of the bacterial colony can be described by all the following, except

Correct AnswerverifiedShow Answer

Colonies growing on the SBA have discolored the media to a green color around and under the colonies. This is consistent with which type of hemolysis?

Correct AnswerverifiedShow Answer

A term used to describe colonies that resemble coins is

Correct AnswerverifiedShow Answer

Swarming is

Correct AnswerverifiedShow Answer

Alph ( β\betaβ ) -hemolysis is

Correct AnswerverifiedB

Beta ( β\betaβ ) -hemolysis is

Correct AnswerverifiedShow Answer

When looking at a tube of thioglycollate broth, streamers or vines and puffballs are visible. What organism grows like this in thioglycollate?

Correct AnswerverifiedShow Answer

All the following colors are commonly used to describe bacteria, except

Correct AnswerverifiedShow Answer

Colonies of Bacillus anthracis are described as

Correct AnswerverifiedShow Answer

Plate reading is

Correct AnswerverifiedShow Answer

A microbiologist is reading a vaginal culture. She sees the very white colonies that are non -hemolytic on a BAP but appear to have feet. What organism could this possibly be?

Correct AnswerverifiedShow Answer

The relative concentration of bacteria on culture plates is directly proportional to

Correct AnswerverifiedShow Answer

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C

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Gamma ( $\gamma$ ) -hemolysis is

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C

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Alph ( $\beta$ ) -hemolysis is

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B

Beta ( $\beta$ ) -hemolysis is

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