week 10 quiz Flashcards

Which structures are less susceptible to UV damage?

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

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

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

• CTTGAATTAA
• GCATGACATA
• ATGCACATGA
• GACACGTAGA

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.

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

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

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

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

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

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

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

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

• bacteria
• viruses
• prions
• fungi
• protozoa

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.

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