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BIOD171 > Module 4 > Flashcards

Module 4 Flashcards

1
Q

True or False: Differential media is best suited for distinguishing between two similar species of bacteria

A

True

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2
Q

A researcher is asked to determine which of two vials contains E coli and which contains salmonella. Knowing both are Gram-negative while only one of them is capable of fermenting lactose, which type of media would be best suited?

A

Differential Media

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3
Q

What are the requirements of a fastidious microbe?

A

A fastidious microbe requires specific and often complex nutritional and environmental conditions to grow and thrive.

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4
Q

True or False: LB agar is classified as a selective, non-differential media.

A

F

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5
Q

The polysaccharide-based hardening agent added to LB media to produce LB agar is derived from what?

A

Seaweed (algae) extract.

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6
Q

Blood agar is which type of medium? Select all that apply.

Selective
Enriched
Selective and Differential
Differential

A

Enriched
Differential

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7
Q

Match the following hemolytic class with its description of activity.

  1. Alpha hemolysis A. No change.
  2. Beta hemolysis B. Greenish-brown color
  3. Gamma hemolysis C. Distinct zone of clearing
A
  1. Alpha hemolysis –> B. Greenish-brown color
  2. Beta hemolysis —> C. Distinct zone of clearing
  3. Gamma hemolysis –> A. No change.
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8
Q

Columbia CNA agar is most closely related to which media:

A

Blood agar

CNA agar is similar to BAP as it is also enriched with blood and allows for differentiation based on hemolytic patterns.

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9
Q

True or False: Chocolate agar gets its brown color from cocoa to produce an enriched media.

A

F

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10
Q

An unknown microbe is streaked onto a MacConkey agar plate. After an overnight incubation at 37°C, growth is observed. Would a Gram stain be necessary? Why or why not?

A

No. A Gram stain would not be necessary, as only Gram-Negative microbes will grow on MacConkey agar.

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11
Q

In Eosin Methylene Blue (EMB) agar, what color indicates the presence of E. coli?

A

metallic green

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12
Q

Which type of agar media is best suited to support the growth of Staphylococcus?

A

Mannitol salt agar

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13
Q

What is the process of spreading a bacterial culture onto a petri dish called?

A

Plating

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14
Q

Describe the primary advantage of using a petri dish over growing a liquid culture?

A

Using a petri dish allows for the microbes to be held in place and be easier controlled in terms of isolation.

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15
Q

True or False: The visualization of colonies on a petri dish represents bacterial cells that have multiplied ~2-3 times.

A

F

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16
Q

True or False. The purpose of a quadrant streak is to expand a bacterial population.

A

F

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17
Q

Which of the following are correct in order to be considered a pure culture? Select all that apply.

Single organism
Multiple species
Obtained by a serial dilution method
Obtained by pour plate serial dilution method
Obtained by a 4-phase dilution streak method
Long lifespan
Free from contaminants

A

Single organism
Obtained by a serial dilution method
Obtained by pour plate serial dilution method
Obtained by a 4-phase dilution streak method
Free from contaminants

18
Q

A dilution gradient is formed when carrying out what generalize plating strategy?

A

A quadrant streak

19
Q

In what phase of a dilution streak would you expect to find the lowest concentration of bacteria, P2 or P4?

A

P4 (Phase 4) would contain the lowest concentration of bacteria. The phases rank (from highest to lowest), P1 > P2 > P3 > P4.

20
Q

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.

A

False

21
Q

What might a researcher do when performing a phase dilution streak to encourage growth of single colonies if starting from a highly concentrated culture?

A

Increase the number of dilution phases on the plate

22
Q

True or False. Pathogenic strains of bacteria tend to grow slower than normal non-pathogenic bacterial strains.

A

F

23
Q

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?

MSA agar
LB media
MacConkey agar
Columbia CNA agar

A

LB media, because this type of media is non-selective and non-differential.

24
Q

What is another name for a liquid growth media, what are the basic components?

A

Nutrient broth. The basic components are sugar, amino acids, and vitamins.

25
Q

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? Based upon what you know about the formulation of differential plates, explain why you chose this specific agar.

A

To detect E. coli O157, the researcher should use MacConkey Sorbitol agar. This agar differentiates E. coli O157
from other E. coli strains by its inability to ferment sorbitol, resulting in colorless colonies compared to pink colonies of sorbitol-fermenting strains.

26
Q

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?

Growth Media
Selective Media
Selective and Differential Media
Differential Media

A

Selective Media

27
Q

What is the Gram status (positive or negative) of microbes growing on Eosin Methylene Blue (EMB) agar plates?

A

Gram-negative

28
Q

Which type of agar media is best suited to support the growth of Staphylococcus?

Columbia CNA agar
Blood agar
Chocolate agar
Mannitol salt agar
MacConkey agar

A

Mannitol Salt Agar

29
Q

What is agar used for in microbiology?

A

Its used to create a solid and smooth surface so microbes can grow on

30
Q

Mannitrol salt agar will turn what color in the presence of the pathogenic strain staphylococcus aureus.

A

Yellow

31
Q

What is the process of spreading a bacterial culture onto a petri dish?

A

Plating

32
Q

In order to visual individual colonies of bacteria would you culture your sample in a liquid media or on a solid (agar) media? Why?

A

Solid Agar. Because the liquid media is where bacterial cells can multiply but are able to move around in the solution; whereas, bacteria plated on a solid agar are fixed and support the formation and visualization of colonies.

33
Q

True or False: The visualization of colonies on a petri dish represents bacterial cells that have often multiplied a million times over.

A

True

34
Q

True or False. The purpose of a quadrant streak is to produce individual colonies of a bacterial population.

A

True

35
Q

True or False: The purpose of the quadrant streak is to expand bacterial population

A

False

36
Q

To be considered a pure culture, the sample (1) ______(2)__________ ?

A

Traced back to a single cell and not have any contaminents

37
Q

In what phase of a dilution streak would you expect to find the lowest concentration of bacteria, P2 or P4?

A

P4

38
Q

In order to encourage growth of a slow growing microbe what might a researcher do during a phase dilution streak?

A

A researcher could either choose to involve fewer phases (3 phases instead of 4) or pass the loop through the previous phase numerous times (instead of only once).

39
Q

True or False. Pathogenic strains of bacteria tend to grow slower than normal non-pathogenic bacterial strains.

A

F

40
Q

True or False; To restrict growth of a pathogenic microbe a researcher might decrease an incubator from 37 to 25C

A

T

41
Q

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

A

LB Media

BIOD171 (7 decks)

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