Testing Exam Questions With Detailed Verified
Answers (100% Correct Answers /Already
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In the bacterial growth cycle, growth ceases because nutrients are exhausted or
toxic metabolic products have accumulated in which phase? - CORRECT ANSWER
✔✔- Stationary phase
(plateau ceases-nutrients exhausted/toxic)
Which of the following genera of bacteria form spores? - CORRECT ANSWER ✔✔-
Bacillus and Clostridium
endospores-non feeding, non motile, non reproductive
-highly resistant to heat, drying, freezing; toxic chemical & radiation.
(Sporulating bacteria-bacteria in which spores are forming)
What term is used to describe bacteria that grow in the absence of atmospheric
oxygen and obtain oxygen from oxygen-containing compounds? - CORRECT
ANSWER ✔✔- Anaerobes
Aerobes - CORRECT ANSWER ✔✔- grows in presence of (free) O2
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,Capnophiles - CORRECT ANSWER ✔✔- growth enhanced by increased CO2
aerotolerants - CORRECT ANSWER ✔✔- does not grow well but tolerate (survive)
in presence of oxygen
What is the temperature at which bacteria grow best known as? - CORRECT
ANSWER ✔✔- Optimum
mesophilic - CORRECT ANSWER ✔✔- grows best 35-37C; most organisms will
grow at 20C
thermophilic - CORRECT ANSWER ✔✔- heat loving (50*55C); autoclaving
procedures
psychotrophilic - CORRECT ANSWER ✔✔- cold loving (10C)-blood bank
contaminancts
On blood agar plates a small zone of alpha hemolysis surrounded by a zone of
beta hemolysis after refrigeration is known as what type of hemolysis? - CORRECT
ANSWER ✔✔- Alpha-prime hemolysis
-Beta hemolysis (clear, colorless-complete hemolysis)
-alpa hemolysis (green, incomplete hemolysis)
-Gamma hemolysis (no hemolysis)
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,What is the most effective method of sterilization? - CORRECT ANSWER ✔✔-
Autoclaving (steam at 121C @ 16 lbs pressure for 15-30 min)-**QC Bacillus
STEAROTHERMOPHILUS
-boiling method (kills all veg-not all spores/viruses (100C for 15-30 min)
Under Fractional Sterilization (used to sterilize media containing mile or serum)
-alternate heating which kills vegetative cells, followed by incubation when spores
germinate, followed by heating, which kills the remaining
tyndallization-flowing steam for 30 min on 3 successive days
-inspissation-75-80C for 2 hrs on 3 successive days
Which of the following is used for quality control for the dry heat oven? -
CORRECT ANSWER ✔✔- Bacillus subtilis
Dry Heat method
-kills by oxidation
-oven 160-180C for 1-2 hours
-QUALITY CONTROLS (Bacillus Subtilis)
Media that cannot be heated can be sterilized by what alternate method? -
CORRECT ANSWER ✔✔- Filtration
asbestos filter-98% effective
membrane filter-0.22 micron = 100% bacterial sterility
for media that are degraded by heat;
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, Which one of the following disinfectants is the most effective germicide against
bacteria, spores, tubercle bacilli, fungi, and viruses? - CORRECT ANSWER ✔✔-
Chlorine (bleach)
oxidizes organic matter
2% aqueous glutaraldehyde
safe for delicate lensed instruments
poor activity against Pseudomonas
What is a term that describes a process or treatment that renders a medical
device, instrument, or environmental surface safe to handle? - CORRECT ANSWER
✔✔- Decontamination
process can range from sterilization or disinfection to just cleaning with soap and
water
What term describes the morphology of organisms that vary in shape and size? -
CORRECT ANSWER ✔✔- Pleomorphic
i.e. coccobacilli
Bacteriology arrangements: - CORRECT ANSWER ✔✔- -pairs (diplococci "N. Gon";
diplobacilli
-chains (streptococci, streptobacilli)
-grape like clusters (staphylococci)
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