_____________ is the appropriate laboratory practices for conducting research with exotic microbes that are highly infectious and pose significant risk to laboratory personnel, but for which there are available treatments.
A. BSL1 B. BSL2 C. BSL3 D. BSL4 E. BSL5 C. BSL3
A particular sterilizati...
MCB 100 Exam 4 Questions and
Complete Solutions
_____________ is the appropriate laboratory practices for conducting research with
exotic microbes that are highly infectious and pose significant risk to laboratory
personnel, but for which there are available treatments.
A. BSL1 B. BSL2 C. BSL3 D. BSL4 E. BSL5 ✅C. BSL3
A particular sterilization process takes 60 minutes to kill all organisms in a sample with
106 microbes. How long does it take to eliminate 99% (2 D-values) of the organisms
using this process? A. 10 minutes B. 20 minutes C. 30 minutes D. 40 minutes E. 50
minutes ✅B. 20 minutes
Consider each of the following statements and determine whether they are true or false,
then select the correct series of responses: - Moist-heat sterilization methods require
application of higher temperatures for longer periods of time than dry-heat sterilization
methods. - Pasteurization is a method of sterilization that kills microbes present in food.
- The goal of tyndallization is to rid canned produce of Clostridium botulinum
endospores. A. true, false, false B. false, false, true C. false, true, true D. false, false,
false E. true, true, true ✅B. false, false, true
In an autoclave, the application of ______ to _______ is increased to allow the _______
to achieve temperatures above the boiling point of water. A. pressure | steam | agar B.
heat | pressure | agar C. pressure | steam | steam D. heat | medium | steam E. heat |
water | medium ✅C. pressure | steam | steam
Which of the following microbial control methods does not actually kill the microbes or
inhibit their growth? A. Desiccation B. Autoclaving C. Freeze-drying D. Irradiation E.
Filtration ✅E. Filtration
Which of the following chemical disinfectants works by methylating enzymes and
nucleic acids and is known for being toxic? A. Bleach B. Acidic acid C. Triclosan D.
Formaldehyde E. Hexachlorophene ✅A. Bleach C. Triclosan
Bleach is an example of which group of chemicals used for disinfection? A. Detergent B.
QACs C. Halogens D. Phenolics E. Alkylating agent ✅C. Halogens
Which of the following best defines selective toxicity for an antimicrobial drug? A. When
a drug is effective against many different types of microbe. B. When a drug is effective
at very low concentrations. C. When a drug is more inhibitory against a pathogen than
the host. D. When a drug specifically kills one type of pathogen, but not another. E.
When a drug can be taken up by the host and retain its activity. ✅C. When a drug is
more inhibitory against a pathogen than the host.
, Which of the following classes of antimicrobial drug would be most likely to block DNA
replication or RNA synthesis? A. Sulfonamides B. Beta-Lactams C. Amphotericin B D.
Nucleoside Analogs E. Aminoglycosides ✅D. Nucleoside Analogs
What is the general mechanism of action of most antibiotics that inhibit proteins
synthesis? A. Causing ribosomes to translate too fast and make mistakes B. Preventing
ribosomes from forming or moving along mRNA. C. Making ribosomes to translate DNA
instead of RNA. D. Enzymatically degrading ribosomes. E. Causing ribosomes to add
incorrect amino acids . ✅B. Preventing ribosomes from forming or moving along
mRNA.
Which of the following drugs has the narrowest spectrum of activity? A. Azoles B.
Sulfonamides C. Streptomycin D. Polymixin E. Penicillin ✅D. Polymixin
Which of the following drugs would make the worst antimicrobial based on therapeutic
index? A. Drug A B. Drug B C. Drug C D. Drug D E. All these drugs would make poor
antimicrobials ✅D. Drug D
Which of the following microbes not an emerging medical problem because of multidrug
resistance? A. Staphylococcus aureus (MRSA) B. Giardia lamblia C. Acenitobacter
baumanii D. Klebsiella pneumoniae E. Mycobacterium Tuberculosis ✅B. Giardia
lamblia
Which of the following is an example of XDR Staphylococcus aureus? A. Resistance to
b-lactams (methicillin) + erythromycins B. Resistance to b-lactams (methicillin) +
erythromycins + fluoroquinolones C. Resistance to the last drug of choice for S. aureus
(fluoroquinolone, aka Cipro) D. Resistance to isoniazid + rifampicin E. Resistance to
isoniazid + rifampicin + ethambutol + pyrazinamide ✅B. Resistance to b-lactams
(methicillin) + erythromycins + fluoroquinolones
Rank the following antibiotics from best to worst? A. A, B, C, D B. B, A, D, C C. C, B, A,
D D. B, C, D, A E. D, A, B, C ✅D. B, C, D, A
How many of the following mechanisms do bacteria use to develop antibiotic resistance:
1) generate a mutation to alter the antibiotic target protein, 2) add a functional group to
the antibiotic, 3) mutate a current protein to have a completely new activity to destroy
the antibiotic, 4) use efflux pumps to pump out antibiotics faster than they can
accumulate in the bacterial cell 5) acquire a conjugative plasmid harboring an antibiotic
resistance gene. A.1 B.2 C.3 D.4 E.5 ✅A, B, C, D, E
Which of the following is not a large roadblock for developing and bringing new
antimicrobial drugs to market? A.Lack of a need for new antimicrobial drugs B.Strict
Government Regulations C.Screening new chemical compounds D.Money E.Time
✅A.Lack of a need for new antimicrobial drugs
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