MICROBIOLOGY BIO 420 EXAM
1 QUESTIONS AND ANSWERS
2026 - 2027
___destroys microbes directly
Damages DNA
Used to destroy microbes in air, water, and on surfaces
Ultraviolet radiation
What type of radiation has poor penetrating power:
Thin films or coverings can limit effect
Cannot kill microbes in solids or turbid liquids
Most glass and plastic block
Ultraviolet radiation
What type of radiation kills by generated heat
Microwaves
microwave ovens often heat food unevenly, so even heat-sensitive
cells can sometimes survive the process.
High Pressure Processing (HPP)
a method used to pasteurize foods by exposing the items to pulses of
high pressure, which destroys the microorganisms that are present
Destroys microbes by denaturing proteins and altering cell
permeability
Products maintain color, flavor associated with fresh food
,Refrigeration inhibits growth of pathogens and spoilage
organisms by slowing or stopping enzyme reactions
What can still grow?
Psychrotrophs, psychrophilic organisms can still grow
These can destroy all microbes including endospores and viruses
are used to treat heat-sensitive critical instruments (instruments
that come into contact with body tissues).
Sterilants
These destroy all viruses and vegetative microorganisms, but they
do not reliably kill endospores.
They are used to treat semicritical instruments
High-level disinfectants
These destroy all vegetative bacteria (including mycobacteria), as
well as fungi, and most, but not all, viruses. They do not kill
endospores even with prolonged exposure. This group of
germicides is used to disinfect non-critical instruments such as
stethoscopes.
Intermediate-level disinfectants
These destroy fungi, vegetative bacteria except mycobacteria, and
enveloped viruses. They do not kill endospores, nor do they
always destroy non-enveloped viruses.
These disinfectants are also called general-purpose disinfectants.
In hospitals, they are used for disinfecting furniture, floors, and
walls.
Low-level disinfectants
reducing available water
, Accomplished by salting, adding sugar, or drying food
disinfectant vs antiseptic
Antiseptics = used on people, low toxicity for humans
Disinfectants = inhibits or kills microorganisms
'Auntie-septics can be used on your Aunties' - used on people
work by disrupting the cell membrane causing bacterial lysis
kill most vegetative bacteria
Mycobacterium at high concentrations
Not reliable on all virus groups
leave antimicrobial residue
Some sufficiently non-toxic; used in soaps, lotions
Phenolic Compounds
used as antiseptics to clean skin in preparation for procedures
that break intact skin, and as
disinfectants for treating instruments.
coagulates essential proteins
Evaporates quickly, limiting contact time
Can damage rubber, some plastics, and others
Alcohols
cause cross-linking that inactivates proteins and nucleic acids
Used to kill bacteria and inactivate viruses for vaccines
1 QUESTIONS AND ANSWERS
2026 - 2027
___destroys microbes directly
Damages DNA
Used to destroy microbes in air, water, and on surfaces
Ultraviolet radiation
What type of radiation has poor penetrating power:
Thin films or coverings can limit effect
Cannot kill microbes in solids or turbid liquids
Most glass and plastic block
Ultraviolet radiation
What type of radiation kills by generated heat
Microwaves
microwave ovens often heat food unevenly, so even heat-sensitive
cells can sometimes survive the process.
High Pressure Processing (HPP)
a method used to pasteurize foods by exposing the items to pulses of
high pressure, which destroys the microorganisms that are present
Destroys microbes by denaturing proteins and altering cell
permeability
Products maintain color, flavor associated with fresh food
,Refrigeration inhibits growth of pathogens and spoilage
organisms by slowing or stopping enzyme reactions
What can still grow?
Psychrotrophs, psychrophilic organisms can still grow
These can destroy all microbes including endospores and viruses
are used to treat heat-sensitive critical instruments (instruments
that come into contact with body tissues).
Sterilants
These destroy all viruses and vegetative microorganisms, but they
do not reliably kill endospores.
They are used to treat semicritical instruments
High-level disinfectants
These destroy all vegetative bacteria (including mycobacteria), as
well as fungi, and most, but not all, viruses. They do not kill
endospores even with prolonged exposure. This group of
germicides is used to disinfect non-critical instruments such as
stethoscopes.
Intermediate-level disinfectants
These destroy fungi, vegetative bacteria except mycobacteria, and
enveloped viruses. They do not kill endospores, nor do they
always destroy non-enveloped viruses.
These disinfectants are also called general-purpose disinfectants.
In hospitals, they are used for disinfecting furniture, floors, and
walls.
Low-level disinfectants
reducing available water
, Accomplished by salting, adding sugar, or drying food
disinfectant vs antiseptic
Antiseptics = used on people, low toxicity for humans
Disinfectants = inhibits or kills microorganisms
'Auntie-septics can be used on your Aunties' - used on people
work by disrupting the cell membrane causing bacterial lysis
kill most vegetative bacteria
Mycobacterium at high concentrations
Not reliable on all virus groups
leave antimicrobial residue
Some sufficiently non-toxic; used in soaps, lotions
Phenolic Compounds
used as antiseptics to clean skin in preparation for procedures
that break intact skin, and as
disinfectants for treating instruments.
coagulates essential proteins
Evaporates quickly, limiting contact time
Can damage rubber, some plastics, and others
Alcohols
cause cross-linking that inactivates proteins and nucleic acids
Used to kill bacteria and inactivate viruses for vaccines
