Which structures are less susceptible to UV damage?

• Fungal spores
• Endospores
• Protozoan cysts
• Vegetative bacterial cells

• Endospores
• Protozoan cysts

Which of the following would be appropriately sterilized using UV radiation?

• flask of nutrient broth
• stack of plastic petri dishes, prior to pouring media
• stainless steel surface in biological safety cabinet used for media preparation
• nutrient agar plates with lids

• stainless steel surface in biological safety cabinet used for media preparation

Which of the following DNA sequences would be the most likely to be damaged by UV radiation?

• CTTGAATTAA
• GCATGACATA
• ATGCACATGA
• GACACGTAGA

• CTTGAATTAA

How is an antiseptic different from a disinfectant?

• An antiseptic is used to remove or kill microorganisms IN the body, whereas a disinfectant is used to remove or kill microorganisms on the body surfaces.
• An antiseptic kills or inactivates all microbial forms but a disinfectant does not destroy endospores.
• There is essentially no difference and these terms can be used interchangeably.
• An antiseptic is used to remove or kill microorganisms on tissue, whereas a disinfectant is used to remove or kill microorganisms on inanimate objects.

• An antiseptic is used to remove or kill microorganisms on tissue, whereas a disinfectant is used to remove or kill microorganisms on inanimate objects.

How are agar plates inoculated for disk diffusion testing of antiseptics and disinfectants?

• A loop is used to prepare a 4-way quadrant streak
• A loop is used to prepare a lawn of growth by inoculating the entire surface of the plate
• A swab is used to inoculate the entire surface of the plate, producing a lawn of growth
• A four-way quadrant streak is done using a swab

• A swab is used to inoculate the entire surface of the plate, producing a lawn of growth.

UV light has ______ wavelengths than visible light waves, and its peak energy is at a wavelength of ______.

• longer; 254nm
• longer; 100nm
• shorter; 100nm
• shorter; 254nm

• shorter; 254nm

Place these types of bacteria in order of their susceptibility to chemical disinfection, from least susceptible to most susceptible.

• Gram-positive bacteria
• Acid-fast bacteria
• Gram-negative bacteria
• Bacterial endospores

1. Bacterial endospores
2. Acid-fast endospores
3. Gram-negative bacteria
4. Gram-positive bacteria

What two factors increase the effectiveness of a disinfectant on microorganisms?

• Concentration of disinfectant
• Time of exposure
• Material used to apply disinfectant
• Corrosiveness of the disinfectant

• Concentration of disinfectant
• Time of exposure

Which of the following are limitations of using UV radiation for disinfection?

• UV radiation does not penetrate through paper, plastics, or liquids
• UV radiation damages plastics and other nonmetal materials
• UV radiation destroys bacteria but not viruses
• UV radiation can damage the skin and eyes

• UV radiation does not penetrate through paper, plastics, or liquids
• UV radiation can damage the skin and eyes

The clear area of devoid of bacterial growth around an antiseptic or disinfectant disk is referred to as the

• zone of death
• no growth zone
• death zone
• zone of inhibition

• zone of inhibiton

When two adjacent thymine molecules are joined by a covalent bond as a result of exposure to UV light, this structure is referred to as a

• thymine dimer
• thymine couplet
• thymine duplex
• thymine doublet

• thymine dimer

Which of the following infectious agents is least likely to be damaged by UV exposure?

• bacteria
• viruses
• prions
• fungi
• protozoa

• prions

Place these steps in the order in which they will be performed when setting up a disk diffusion assay to test the effectiveness of disinfectants and antiseptics.

• Using a swab, inoculate a suspension of the bacteria being tested onto an agar plate, spreading the inoculum over the entire surface.
• Saturate sterile filter paper disks with the test chemical (disinfectant or antiseptic) and place onto the inoculated agar plate. Repeat with each chemical being tested.
• Observe plates to determine the presence of a zone of inhibition around each antiseptic or disinfectant disk.
• Incubate inoculated agar plates overnight to promote bacterial growth.

1. Using a swab, inoculate a suspension of the bacteria being tested onto an agar plate, spreading the inoculum over the entire surface.
2. Saturate sterile filter paper disks with the test chemical (disinfectant or antiseptic) and place onto the inoculated agar plate. Repeat with each chemical being tested.
3. Incubate inoculated agar plates overnight to promote bacterial growth.
4. Observe plates to determine the presence of a zone of inhibition around each antiseptic or disinfectant disk.

Which of the following would affect the size of a zone of inhibition around an antiseptic or disinfectant disk?

• The susceptibility of the microorganism to the chemical
• The concentration of chemical in the disk
• The cellular target of the chemical
• How quickly the chemical diffuses through the agar
• The depth of the agar

• The concentration of chemical in the disk
• How quickly the chemical diffuses through the agar
• The depth of the agar
• The susceptibility of the microorganism to the chemical