Microbiology, 2021

366 9 • Review Questions
40. Blood agar contains many unspecified
nutrients, supports the growth of a large
number of bacteria, and allows differentiation
of bacteria according to hemolysis (breakdown
of blood). The medium is ________ and
________.
Short Answer
42. Why is it important to measure the
transmission of light through a control tube
with only broth in it when making turbidity
measures of bacterial cultures?
43. In terms of counting cells, what does a plating
method accomplish that an electronic cell
counting method does not?
44. Order the following stages of the development of
a biofilm from the earliest to the last step.
1. secretion of EPS
2. reversible attachment
3. dispersal
4. formation of water channels
5. irreversible attachment
45. Infections among hospitalized patients are
often related to the presence of a medical device
in the patient. Which conditions favor the
formation of biofilms on in-dwelling catheters
and prostheses?
46. Why are some obligate anaerobes able to grow
in tissues (e.g., gum pockets) that are not
completely free of oxygen?
41. Rogosa agar contains yeast extract. The pH is
adjusted to 5.2 and discourages the growth of
many microorganisms; however, all the colonies
look similar. The medium is ________ and
________.
47. Why should Haemophilus influenzae be grown
in a candle jar?
48. In terms of oxygen requirements, what type of
organism would most likely be responsible for a
foodborne illness associated with canned
foods?
49. Which macromolecule in the cell is most
sensitive to changes in pH?
50. Which metabolic process in the bacterial cell is
particularly challenging at high pH?
51. How are hyperthermophile’s proteins adapted
to the high temperatures of their environment?
52. Why would NASA be funding microbiology
research in Antarctica?
53. Fish sauce is a salty condiment produced using
fermentation. What type of organism is likely
responsible for the fermentation of the fish
sauce?
54. What is the major difference between an
enrichment culture and a selective culture?
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