Basic Principles of Microbial Control
Which structure maintains a microbial cell’s integrity and can cause bursting if damaged?
A. Ribosome
B. Cytoplasmic membrane
C. Cell wall
D. Flagellum
C. Cell wall
Which biosafety level is used for microbes that do NOT cause human disease?
A. BSL-1
B. BSL-2
C. BSL-3
D. BSL-4
A. BSL-1
Standard autoclave conditions are:
A. 100°C, 10 psi, 10 min
B. 121°C, 15 psi, 15 min
C. 140°C, 5 psi, 5 min
D. 80°C, 20 psi, 30 min
B. 121°C, 15 psi, 15 min
Alcohols act by:
A. Cross-linking DNA
B. Denaturing proteins and disrupting membranes
C. Removing water
D. Forming radicals
B. Denaturing proteins and disrupting membranes
A disinfectant with a phenol coefficient of 1.5 is:
A. Less effective than phenol
B. Equal to phenol
C. More effective than phenol
D. Ineffective
C. More effective than phenol
Denaturation primarily affects which cellular component?
A. Lipids
B. Proteins
C. Carbohydrates
D. Capsules
B. Proteins
BSL-2 labs handle:
A. Harmless microbes
B. Moderately hazardous agents
C. Fatal pathogens only
D. Prions exclusively
B. Moderately hazardous agents
Boiling kills:
A. Endospores
B. Protozoan cysts
C. Vegetative bacterial cells
D. All viruses
C. Vegetative bacterial cells
Chlorine and iodine belong to which group?
A. Alcohols
B. Phenolics
C. Halogens
D. Surfactants
C. Halogens
The in-use test evaluates:
A. Radiation dose
B. Proper strength and application of disinfectants
C. Autoclave pressure
D. Endospore heat resistance
B. Proper strength and application of disinfectants
A chemical causes leakage of cellular contents. It most likely damaged the:
A. DNA
B. Ribosomes
C. Cytoplasmic membrane
D. Endospore coat
C. Cytoplasmic membrane
All manipulations must occur inside safety cabinets in:
A. BSL-1
B. BSL-2
C. BSL-3
D. BSL-4
C. BSL-3
UV light kills microbes by:
A. Oxidizing enzymes
B. Denaturing membranes
C. Forming pyrimidine dimers in DNA
D. Increasing osmotic pressure
C. Forming pyrimidine dimers in DNA
Hydrogen peroxide kills microbes by:
A. Forming dimers
B. Oxidizing enzymes
C. Lowering pH
D. Blocking ribosomes
B. Oxidizing enzymes
An ideal antimicrobial should be:
A. Expensive and slow-acting
B. Fast-acting, stable, inexpensive, and harmless
C. Toxic to humans
D. Light-sensitive
B. Fast-acting, stable, inexpensive, and harmless
An antimicrobial that causes fatal mutations most directly affects:
A. Peptidoglycan
B. Lipopolysaccharide
C. Nucleic acids
D. Glycocalyx
C. Nucleic acids
A microbe causing severe, often fatal disease requires:
A. BSL-2
B. BSL-3
C. BSL-4
D. Standard lab bench
C. BSL-4
Ionizing radiation kills cells primarily by:
A. Dehydration
B. Creating ions and hydroxyl radicals that damage DNA
C. Freezing cytoplasm
D. Removing capsules
B. Creating ions and hydroxyl radicals that damage DNA
Glutaraldehyde works by:
A. Dehydrating cells
B. Cross-linking functional groups in proteins and DNA
C. Disrupting capsules
D. Dissolving lipids
B. Cross-linking functional groups in proteins and DNA
Why might fungi survive high sugar environments?
A. They lack membranes
B. They tolerate hypertonic conditions better than bacteria
C. They form endospores
D. They resist radiation
B. They tolerate hypertonic conditions better than bacteria
Which situation best explains microbial death due to osmotic lysis?
A. Heat denatures enzymes
B. UV light forms dimers
C. Cell wall damage causes water influx and rupture
D. Alcohol disrupts lipids
C. Cell wall damage causes water influx and rupture
A researcher working with an aerosol-transmitted lethal virus would require:
A. BSL-1 with gloves
B. BSL-2 with goggles
C. BSL-3 without cabinet
D. BSL-4 with isolated lab and protective suit
D. BSL-4 with isolated lab and protective suit
Why is moist heat more effective than dry heat?
A. It oxidizes proteins faster
B. It penetrates cells and denatures proteins more efficiently
C. It freezes membranes
D. It increases osmotic pressure
B. It penetrates cells and denatures proteins more efficiently
Quaternary ammonium compounds are best described as:
A. High-level sterilants
B. Oxidizing agents
C. Low-level disinfectant surfactants that disrupt membranes
D. Ionizing gases
C. Low-level disinfectant surfactants that disrupt membranes
Why is pasteurization NOT considered sterilization?
A. It uses dry heat
B. It causes oxidation
C. Heat-tolerant microbes can survive
D. It increases pressure
C. Heat-tolerant microbes can survive