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MICRB 107 - Exam 2 > Physical and Chemical Methods of Controlling Microbial Growth > Flashcards

Physical and Chemical Methods of Controlling Microbial Growth Flashcards

1
Q

Is UV radiation ionizing or nonionizing?

A

Nonionizing

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2
Q

The distance between adjacent wave crests is known as ______

A

Wavelength

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3
Q

What are the units of electromagnetic radiation?

A

Nanometers (nm)

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4
Q

What is the relationship between wavelength and energy?

A

Shorter wavelength = greater energy

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5
Q

Is UV light of shorter or longer wavelength than X rays or gamma rays?

A

Shorter

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6
Q

What is the range of UV-A wavelength?

A

315 - 400 nm

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7
Q

What is the range of UV-B wavelength?

A

280 - 315 nm

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8
Q

What is the range of UV-C wavelength?

A

100 - 280 nm

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9
Q

Bacterial exposure to UV-C for more than a few minutes usually results in …

A

DNA damage and death of the organism

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10
Q

Lethal effects of UV light are due to its ______

A

Mutagenic properties

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11
Q

What is a pyrimidine?

A

Covalent bonds between 2 adjacent thymine / cytosine bases

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12
Q

DNA absorbs UV radiation maximally at ______, resulting in pyrimidine dimers

A

260 nm

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13
Q

What are the 2 main environmental factors that affect the killing properties of UV light?

A
  • Time of exposure
  • Materials that block radiation from reaching cells
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14
Q

Which are more resistant to UV light - endospores or vegetative cells?

A

Endospores

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15
Q

______ protect DNA from photochemical damage

A

Small, acid-soluble proteins

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16
Q

UV light induces ______ during endospore germination

A

Enzymatic repair of damaged DNA

17
Q

Substances designed to reduce the number of pathogens or spoilage organisms on a surface, in a liquid or in living tissue are known as ______

A

Chemical germicides

18
Q

What does sepsis mean?

A

Contamination by microorganisms

19
Q

The use-dilution test is used to measure the effectiveness of disinfectants against … (3)

A
  • S. aureus
  • P. aeruginosa
  • Salmonella enterica
20
Q

What chemical was used in the modified use-dilution test as performed in the lab?

A

Household bleach

21
Q

What was household bleach tested on for the use-dilution test performed in the lab? (2)

A
  • S. epidermidis
  • E. coli

MICRB 107 - Exam 2 (3 decks)

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