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An antibacterial agent is considered static if it ___________________
An antibacterial agent is considered static if it doesn’t kill the bacteria, but stops their growth completely
. Which of the following statements is true regarding the spores of Clostridium botulinum?
a. boiling water is cidal after about 9 hours
b. water at 1210 C is cidal after 5 minutes
c. water at 1160 C is cidal after 15 minutes
d. both a and b are correct
e. both a and c are correct
a. boiling water is cidal after about 9 hours
According to the idea of exponential death phase, if we had a sample containing 30,000
bacteria, and we autoclaved it for 15 minutes, how many bacteria would be alive at the 4 minute
time?
300
Which of the above characteristics apply to Free Flowing Steam ?
1. Sterilizes 2. Disinfects 3. Protein coagulation 4. Protein oxidation 5. Removes water necessary for enzymatic hydrolysis 6. Destroys only vegetative cells 7. Destroys spores
Free flowing steam:
2 disinfects
3 protein coagulation
6 destroys only vegetative cells
Which of the above characteristics apply to hot air oven?
1. Sterilizes 2. Disinfects 3. Protein coagulation 4. Protein oxidation 5. Removes water necessary for enzymatic hydrolysis 6. Destroys only vegetative cells 7. Destroys spores
hot air oven: 1 sterilizes 3 protein coagulation 4 protein oxidation 5 removes water necessary for enzymatic hydrolysis 7 destroys spores
What is the physical method for controlling bacteria is used prior to filtration in water purification?
sedimentation
What is the physical method for destroying bacteria is used primarily in research labs for studying internal
components of bacterial cells?
sonic vibrations
Which of the following pairs are mismatched?
a. syphilis - destroyed in minutes upon exposure to drying
b. tetanus spores - last indefinitely in dry conditions
c. gonorrhea- destroyed in an hour or so upon exposure to drying
d. Hepatitis B - destroyed quickly upon exposure to drying
e. HIV - destroyed quickly upon exposure to drying
d. Hepatitis B - destroyed quickly upon exposure to drying
Hepatitis B will last at least 7 days on a dry surface before being destroyed
Some drugs such as antibiotics are stored in a dry condition for preservation. The mode of
action of bacterial control with this method is ___________
removal of water necessary for enzymatic hydrolysis
Sunlight can be quite effective in killing bacteria. Mycobacterium can be killed in a few hours if
exposed. Currently it is thought that the mode of action of this process is ___________
protein oxidation
Which of the following is NOT TRUE regarding the use of ultraviolet radiation for control of
bacterial growth?
a. it is nonionizing radiation
b. it has a low power of penetration
c. it will cause thymine to bond to another thymine resulting in a mutation
d. it is used for air disinfection in laminar flow hoods
e. the high intensity of light causes photo oxidation
e. the high intensity of light causes photo oxidation
The correct mode of action of UV light is DNA forms pyrimidine dimers which leads to mutation
All of the following statements regarding cold temperatures are true EXCEPT
a. cold temperatures are not usually cidal to bacteria
b. refrigerator temperatures are primarily inhibitory to bacterial growth
c. freezer temperatures are primarily static to bacterial growth
d. the mode of action for freezing is removal of water for enzymatic hydrolysis
e. the mode of action of refrigeration is protein coagulation
e. the mode of action of refrigeration is protein coagulation
Refrigeration is inhibitory, it slows the rate of enzymatic reaction. This slows bacterial growth
All of the following produce hyperactive ions EXCEPT:
a. gamma rays
b. x-rays
c. microwaves
d. cathode rays
e. both c and d are incorrect
c. microwaves
microwaves are too low energy to produce hyperactive ions
Jams and jellies have 50 to 60% sugar concentrations. Therefore, the main reason most bacteria
do not grow in these foods is that their mode of action is _____________
plasmolysis of cells
What is the difference between plasmolysis and plasmoptysis of cells?
Plasmolysis is when a cell shrinks due to water living.
Plasmoptysis is the bursting fourth of protoplasm from a cell, through rupture of the cell wall.
for protein coagulation as a mode of action in chemical methods of control, True or false:
they disrupt the 3-D structure of proteins
true
for protein coagulation as a mode of action in chemical methods of control, True or false:
they stop enzymatic metabolism
true
for protein coagulation as a mode of action in chemical methods of control, True or false:
they are generally cidal
true
for protein coagulation as a mode of action in chemical methods of control, True or false:
they are generally narrow spectrum
false
for protein coagulation as a mode of action in chemical methods of control, True or false:
they cannot generally be used systemically
true
True or false:
chlorhexidene is a phenol derivative
false
True or false:
the mode of action of chlorhexidene is protein coagulation
true
True or false:
chlorhexidene is used for hand scrubbing and preparing sites for surgery
true
True or false:
chlorhexidene is safe since it is not absorbed into the deeper tissues of the skin
true
regarding phenol and its derivatives, true or false:
they remain effective in the presence of organic matter
true
regarding phenol and its derivatives, true or false:
they have analgesic properties
true
regarding phenol and its derivatives, true or false:
they are broad spectrum
true
regarding phenol and its derivatives, true or false:
they are protoplasmic poisons
true
regarding phenol and its derivatives, true or false:
they are useful for systemic control of organisms
false