BIO245 Exam 3 Practice Questions And
Answers 2026 Update!!!
Can halogens be sporicidal?
a. No, halogens are never sporicidal
c. Yes, with extended exposure times b. Yes, but only when combined with heat
c. Yes, with extended exposure times
d. Yes, but only for G+ spores
At the point of what on the Death Curve is
microbial survival unlikely?
a. Lag phase
c. Sterilization
b. Death phase
c. Sterilization
d. Stationary phase
Why are heavy metals not often used for
antimicrobial purposes?
a. Toxic, easy to develop resistance, cause
a. Toxic, easy to develop resistance, cause allergic reactions
allergic reactions b. They only work on viruses
c. Beneficial to most microbes, but cause
antimicrobial resistance in humans
d. They are ineffective against G- bacteria
How is the effectiveness of chemical controls
determined?
a. Temperature and oxygen level
b. Concentration and contact time
b. Concentration and contact time
c. Gram status of the bacteria
d. Light exposure and humidity
,a. When items are too sensitive to withstand When is tyndallization used?
heat from autoclaving
a. When items are too sensitive to withstand
heat from autoclaving
b. When high pressure sterilization is required
, c. When the presence of prions is suspected
d. Most often for surgical tools
What is the sterilization mechanism of ionizing
radiation?
a. Causes ions to form, harming DNA
a. Causes ions to form, harming DNA b. Causes pyrimidine dimers to form, harming
DNA
c. Inhibits cell wall synthesis, leading to cell lysis
d. Lowers surface tension of membrane
What is the mode of action of heat?
a. Disrupts cell wall synthesis
c. Denaturing proteins b. Disrupts cell membrane synthesis
c. Denaturing proteins
d. Blocks DNA replication and transcription
Which microbe is the easiest to get rid of?
a. G- pathogens
b. Enveloped viruses b. Enveloped viruses
c. Fungal sexual spores
d. Prions
Which will not influence the Death Curve?
a. Temperature
c. A homogenous population b. Concentration of microbial agent
c. A homogenous population
d. A mixed microbial population
How many hours of exposure does it take for
aldehydes to be sporicidal?
a. 24 hours
b. 3 hours
b. 3 hours
c. 1 hours
d. 12 hours
E Applied to living tissue Match the disinfection method with the
definitions:
B Physical or chemical. Destroys vegetative
pathogens a. Sanitization
D Destroys or removes all viable microbes b. Disinfection
, A Reduces microbial loads to safe levels c. Antimicrobial
C chemical agent that kills pathogenic microbes d. Sterilization
e. Antiseptic
Applied to living tissue
Physical or chemical. Destroys vegetative
pathogens
Destroys or removes all viable microbes
Reduces microbial loads to safe levels
chemical agent that kills pathogenic microbes
What is the Thermal Death Point?
a. The shortest exposure time necessary to kill all
test microbes at a given
temperature
b. The lowest temperature that can be used to
kill all microbes in a sample in 10 b. The lowest temperature that can be used to
kill all microbes in a sample in 10
minutes
minutes
c. The point below which spores stop forming
d. The time requires to kill half of the microbial
load
Which type of control is used on living tissue?
a. Sterilization
c. Antiseptic b. Disinfectant
c. Antiseptic
d. Bactericides
How do alcohols affect microbes at 50%
concentration?
a. Denature cell membrane proteins
b. Destroy cell membranes b. Destroy cell membranes
c. Block ribosome transcription
d. Forms free radicals to disrupt nucleotide
function
c. 100 °C for 30 minutes What are the parameters for boiling water to
remove vegetable pathogens?
a. 100 °C for 10 minutes
b. 100 °F for 30 minutes
Answers 2026 Update!!!
Can halogens be sporicidal?
a. No, halogens are never sporicidal
c. Yes, with extended exposure times b. Yes, but only when combined with heat
c. Yes, with extended exposure times
d. Yes, but only for G+ spores
At the point of what on the Death Curve is
microbial survival unlikely?
a. Lag phase
c. Sterilization
b. Death phase
c. Sterilization
d. Stationary phase
Why are heavy metals not often used for
antimicrobial purposes?
a. Toxic, easy to develop resistance, cause
a. Toxic, easy to develop resistance, cause allergic reactions
allergic reactions b. They only work on viruses
c. Beneficial to most microbes, but cause
antimicrobial resistance in humans
d. They are ineffective against G- bacteria
How is the effectiveness of chemical controls
determined?
a. Temperature and oxygen level
b. Concentration and contact time
b. Concentration and contact time
c. Gram status of the bacteria
d. Light exposure and humidity
,a. When items are too sensitive to withstand When is tyndallization used?
heat from autoclaving
a. When items are too sensitive to withstand
heat from autoclaving
b. When high pressure sterilization is required
, c. When the presence of prions is suspected
d. Most often for surgical tools
What is the sterilization mechanism of ionizing
radiation?
a. Causes ions to form, harming DNA
a. Causes ions to form, harming DNA b. Causes pyrimidine dimers to form, harming
DNA
c. Inhibits cell wall synthesis, leading to cell lysis
d. Lowers surface tension of membrane
What is the mode of action of heat?
a. Disrupts cell wall synthesis
c. Denaturing proteins b. Disrupts cell membrane synthesis
c. Denaturing proteins
d. Blocks DNA replication and transcription
Which microbe is the easiest to get rid of?
a. G- pathogens
b. Enveloped viruses b. Enveloped viruses
c. Fungal sexual spores
d. Prions
Which will not influence the Death Curve?
a. Temperature
c. A homogenous population b. Concentration of microbial agent
c. A homogenous population
d. A mixed microbial population
How many hours of exposure does it take for
aldehydes to be sporicidal?
a. 24 hours
b. 3 hours
b. 3 hours
c. 1 hours
d. 12 hours
E Applied to living tissue Match the disinfection method with the
definitions:
B Physical or chemical. Destroys vegetative
pathogens a. Sanitization
D Destroys or removes all viable microbes b. Disinfection
, A Reduces microbial loads to safe levels c. Antimicrobial
C chemical agent that kills pathogenic microbes d. Sterilization
e. Antiseptic
Applied to living tissue
Physical or chemical. Destroys vegetative
pathogens
Destroys or removes all viable microbes
Reduces microbial loads to safe levels
chemical agent that kills pathogenic microbes
What is the Thermal Death Point?
a. The shortest exposure time necessary to kill all
test microbes at a given
temperature
b. The lowest temperature that can be used to
kill all microbes in a sample in 10 b. The lowest temperature that can be used to
kill all microbes in a sample in 10
minutes
minutes
c. The point below which spores stop forming
d. The time requires to kill half of the microbial
load
Which type of control is used on living tissue?
a. Sterilization
c. Antiseptic b. Disinfectant
c. Antiseptic
d. Bactericides
How do alcohols affect microbes at 50%
concentration?
a. Denature cell membrane proteins
b. Destroy cell membranes b. Destroy cell membranes
c. Block ribosome transcription
d. Forms free radicals to disrupt nucleotide
function
c. 100 °C for 30 minutes What are the parameters for boiling water to
remove vegetable pathogens?
a. 100 °C for 10 minutes
b. 100 °F for 30 minutes
