MICRO 3060- LAB PRACTICAL FINAL QUESTIONS
WITH VERIFIED ANSWERS
What is UV light? - Answers - wavelengths of the electromagnetic spectrum
What is UV light's wavelength range in nanometers? - Answers - 10-100nm
What type of UV light can kill viruses? - Answers - UV-C
What can UV light cause to form in the base pairs of DNA? - Answers - UV-B or A
UV is only effective in sterilizing/disinfecting in ________________ - Answers - in the
line of sight
how did we examine the germicidal effects of UV light? - Answers - swabbed each sides
of a plate with S. aureus and B. subtilis, all students got different UV exposure times
- paper towel over half of each
- incubate and observe growth using + to +++ or (-) for bacterial growth
What is the the release of ammonia during the decomposition of organic nitrogen
compounds? - Answers - ammonification
How is the presence of ammonification tested in soil? - Answers - by inoculating a
peptone broth with a soil sample
___________ is a surface-attached community of bacterial cells and they typically form
in any aqueous environment. - Answers - biofilm
__________ a chemical compound that kills or inhibits the growth of microorganisms. -
Answers - antimicrobial agent
__________ an antimicrobial agent used only on inanimate objects. - Answers -
disinfectant
___________ chemical agent that kills or inhibits the growth of microorganisms and is
sufficiently nontoxic to be applied on living tissue. - Answers - antiseptic
____________ a medicine that inhibits the growth of or destroys microorganisms. -
Answers - antibiotic
____________ is the ring that forms around the disk after incubation indicating bacterial
sensitivity. - Answers - zone of inhibition
, What are the three levels of sensitivity used to describe the zone of inhibition - Answers
- R - resistant
I - intermediate
S - sensitive
Explain the Filter Paper Disk Method of evaluating the relative effectiveness of various
disinfectants and/or antiseptics. - Answers - - inoculate an agar pour with loopful of
assigned bacteria and poured into empty petri dish- filter paper dipped into assigned
disinfectant and placed in the middle of agar incubated and measured for zone of
inhibition- measures how well the disinfectant worked against organism
where is the zone of inhibition measured from in the Filter Paper Disk Method? -
Answers - edge of the disk to edge of the growth
Explain the Kirby-Bauer Method of evaluating the sensitivity of bacteria to certain
antimicrobial drugs. - Answers - -swab was dipped in broth of assigned bacteria and
streaked through whole agar plate twice at 90º angle
- 4-5 antimicrobial disks were placed on agar and incubated- zone of inhibition
measured
- evaluates for sensitivity of bacteria to antimicrobial
where is the zone of inhibition measured from in the Kirby-Bauer Method? - Answers -
the diameter (whole zone)
What is the purpose of the methylene blue reductase test? - Answers - to indicate the
large numbers of bacteria found in milk
What is MBRT? - Answers - Methylene Blue Reductase Time; the amount of time it
takes for methylene blue to decolorize, the longer the bester the quality of milk
What is the purpose of the standard plate count? - Answers - to determine the number
of viable organisms present in a bacterial culture
What is a coliform? - Answers - A group of gram negative, non spore-forming, aerobic to
facultatively anaerobic rods, which ferment lactose into acid and gases
The presence of water organism in water indicated fecal contamination? - Answers - E.
coli
What type of test is used to test for the presence of coliforms (lactose-fermenting
bacteria that produce gas)? What does a positive result look like? - Answers -
presumptive test; 10% or more gas in the Durham tube
What type of test is used to see if the gas producing bacteria from the presumptive test
are gram negative? - Answers - confirmed test
WITH VERIFIED ANSWERS
What is UV light? - Answers - wavelengths of the electromagnetic spectrum
What is UV light's wavelength range in nanometers? - Answers - 10-100nm
What type of UV light can kill viruses? - Answers - UV-C
What can UV light cause to form in the base pairs of DNA? - Answers - UV-B or A
UV is only effective in sterilizing/disinfecting in ________________ - Answers - in the
line of sight
how did we examine the germicidal effects of UV light? - Answers - swabbed each sides
of a plate with S. aureus and B. subtilis, all students got different UV exposure times
- paper towel over half of each
- incubate and observe growth using + to +++ or (-) for bacterial growth
What is the the release of ammonia during the decomposition of organic nitrogen
compounds? - Answers - ammonification
How is the presence of ammonification tested in soil? - Answers - by inoculating a
peptone broth with a soil sample
___________ is a surface-attached community of bacterial cells and they typically form
in any aqueous environment. - Answers - biofilm
__________ a chemical compound that kills or inhibits the growth of microorganisms. -
Answers - antimicrobial agent
__________ an antimicrobial agent used only on inanimate objects. - Answers -
disinfectant
___________ chemical agent that kills or inhibits the growth of microorganisms and is
sufficiently nontoxic to be applied on living tissue. - Answers - antiseptic
____________ a medicine that inhibits the growth of or destroys microorganisms. -
Answers - antibiotic
____________ is the ring that forms around the disk after incubation indicating bacterial
sensitivity. - Answers - zone of inhibition
, What are the three levels of sensitivity used to describe the zone of inhibition - Answers
- R - resistant
I - intermediate
S - sensitive
Explain the Filter Paper Disk Method of evaluating the relative effectiveness of various
disinfectants and/or antiseptics. - Answers - - inoculate an agar pour with loopful of
assigned bacteria and poured into empty petri dish- filter paper dipped into assigned
disinfectant and placed in the middle of agar incubated and measured for zone of
inhibition- measures how well the disinfectant worked against organism
where is the zone of inhibition measured from in the Filter Paper Disk Method? -
Answers - edge of the disk to edge of the growth
Explain the Kirby-Bauer Method of evaluating the sensitivity of bacteria to certain
antimicrobial drugs. - Answers - -swab was dipped in broth of assigned bacteria and
streaked through whole agar plate twice at 90º angle
- 4-5 antimicrobial disks were placed on agar and incubated- zone of inhibition
measured
- evaluates for sensitivity of bacteria to antimicrobial
where is the zone of inhibition measured from in the Kirby-Bauer Method? - Answers -
the diameter (whole zone)
What is the purpose of the methylene blue reductase test? - Answers - to indicate the
large numbers of bacteria found in milk
What is MBRT? - Answers - Methylene Blue Reductase Time; the amount of time it
takes for methylene blue to decolorize, the longer the bester the quality of milk
What is the purpose of the standard plate count? - Answers - to determine the number
of viable organisms present in a bacterial culture
What is a coliform? - Answers - A group of gram negative, non spore-forming, aerobic to
facultatively anaerobic rods, which ferment lactose into acid and gases
The presence of water organism in water indicated fecal contamination? - Answers - E.
coli
What type of test is used to test for the presence of coliforms (lactose-fermenting
bacteria that produce gas)? What does a positive result look like? - Answers -
presumptive test; 10% or more gas in the Durham tube
What type of test is used to see if the gas producing bacteria from the presumptive test
are gram negative? - Answers - confirmed test
