FDSC 409 Exam 1 Question and answer
correctly solved
aseptic technique - correct answer work under flame within 30cm to prevent
environmental contamination
hazards common in BSL-2 labs - correct answer flame + ethanol
pathogenic organisms (treatable)
2 online resources of microbiological analysis methods - correct answer FDA
BAM (Bacteriological Analytical Manual)
USDA MLG (Microbiology Laboratory Guidebook)
Gram negative vs Gram positive appearance - correct answer gram negative:
stains pink- outer membrane
gram positive: retains crystal violet stain bc of thick peptidoglycan layer
Gram negative example, gram positive example - correct answer gram neg:
E. coli, pseudomonas
gram pos: Clostridium perfringens (welchii), C. botulinum, and Bacillus cereus
How to Calculate CFU/ml - correct answer 1. find dilution factor (Final
volume/volume transferred) & total dilution factor (DF1 * DF2 * DF3...)
, 2. cfu/ml = total dilution factor * colony # / volume of suspension plated (ml)
3. log cfu/ml
phases of bacterial growth curve - correct answer lag: adapting to new env,
still metabolically active
log: exponentially growing
stationary: no growth, nutrient exhaustion
death: more dying than dividing cells
advantages and disadvantages of using growth predictive models (lab 2) -
correct answer advantages: useful in product development to estimate
growth/survival/inactivation
disadvantages: a prediction cannot replace a product-specific test
difference between primary, secondary, tertiary predicative growth models -
correct answer Primary: describe growth over time
secondary: describes growth in response to environmental conditions (temp,
pH, water activity)
tertiary: describes growth kinetics as affected by many env conditions
microbial physiological state - correct answer depends on how stressed
organisms are
measure of how long lag phase will take before growth
correctly solved
aseptic technique - correct answer work under flame within 30cm to prevent
environmental contamination
hazards common in BSL-2 labs - correct answer flame + ethanol
pathogenic organisms (treatable)
2 online resources of microbiological analysis methods - correct answer FDA
BAM (Bacteriological Analytical Manual)
USDA MLG (Microbiology Laboratory Guidebook)
Gram negative vs Gram positive appearance - correct answer gram negative:
stains pink- outer membrane
gram positive: retains crystal violet stain bc of thick peptidoglycan layer
Gram negative example, gram positive example - correct answer gram neg:
E. coli, pseudomonas
gram pos: Clostridium perfringens (welchii), C. botulinum, and Bacillus cereus
How to Calculate CFU/ml - correct answer 1. find dilution factor (Final
volume/volume transferred) & total dilution factor (DF1 * DF2 * DF3...)
, 2. cfu/ml = total dilution factor * colony # / volume of suspension plated (ml)
3. log cfu/ml
phases of bacterial growth curve - correct answer lag: adapting to new env,
still metabolically active
log: exponentially growing
stationary: no growth, nutrient exhaustion
death: more dying than dividing cells
advantages and disadvantages of using growth predictive models (lab 2) -
correct answer advantages: useful in product development to estimate
growth/survival/inactivation
disadvantages: a prediction cannot replace a product-specific test
difference between primary, secondary, tertiary predicative growth models -
correct answer Primary: describe growth over time
secondary: describes growth in response to environmental conditions (temp,
pH, water activity)
tertiary: describes growth kinetics as affected by many env conditions
microbial physiological state - correct answer depends on how stressed
organisms are
measure of how long lag phase will take before growth
