Test 2 Flashcards
The testing method indicates that a food product is negative for the presence of Salmonella Typhimurium, but S. Typhimurium is actually present in a food is an example of what?
a. a false positive
b. a false negative
c. a technician’s mistake
d. poor technique
e. a stupid example
b. a false negative
What component of bacterial spores provides them with heat resistance and DNA stability?
a. high moisture content
b. ethanol
c. dipicolinic acid
d. molasses
e. unguentine
c. dipicolinic acid
Byssochlamys, a juice spoilage mold, is unusual because of its:
a. cold tolerance
b. tolerance to low O2
c. color
d. production of dipicolinic acid
e. tolerance to acid
b. tolerance to low O2
The rind of Brie cheese is composed of what?
a. cracker crumbs
b. salt
c. flour
d. Penicillium camemberti
e. baked cheese curd
d. Penicillium camemberti
Use of this technology for direct counting of bacterial cells involves the use of an antibody conjugated to a
fluorescent dye.
a. direct fluorescent count
b. antibiotic sensitivity testing
c. fluorescent surface plating
d. immunofluorescent direct microscopic count
e. Ouchterlony immunodiffusioncount
d. immunofluorescent direct microscopic count
The presence of bile salts and crystal violet in MacConkey agar makes this medium a:
a. selective medium
b. non-‐selective medium
c. differential medium
d. selective/differential medium
e. lousy choice for detecting bacteria
a. selective medium
Mannitol salt agar is selective/differential medium that is used for detecting/enumerating what organism?
a. E. coli
b. Yersinia pestis
c. Lactobacillus casei
d. Staphylococcus aureus
e. Penicillium camemberti
d. Staphylococcus aureus
Bacteria are commonly eluted (separated) from the surface of food particles using what?
a. column chromatography
b. pressure washer
c. stomacher
d. sandpaper
e. vigorous shaking in a bag of diluent
c. stomacher
Use of this method for determining viable bacterial counts, various volumes of diluent can be deposited into Petri dishes.
a. pour plating
b. spread plating
c. direct microscopic count
d. indirect plating
e. guessing
a. pour plating
Use of hydrophobic grid membrane filtration prevents what?
a. detection of Gram negative bacteria
b. detection of Gram positive bacteria
c. detection of hydrophilic bacteria
d. lateral spread of bacterial colonies
e. detection of bacteria
d. lateral spread of bacterial colonies
Which of the following is NOT an assumption made when agar plating methods are employed?
a. bacterial cells are evenly distributed among the food being sampled
b. bacterial cells are evenly distributed in the dilution fluid matrix
c. every colony arises from one cell
d. the method will detect every viable organism in the food sample
e. there are no assumptions made during such analyses
d. the method will detect every viable organism in the food sample
The smallest number of cells that can be enumerated using a specified agar plating method is referred to as the:
a. zenith
b. minimal bacteria
c. detection limit
d. small count
e. maximal count
c. detection limit
Use of a membrane filter of what size would ensure that all bacterial cells would not pass through?
a. 1 cm
b. 0.1 cm
c. 0.45 μm
d. 0.8 μm
e. 0.22 μm
e. 0.22 μm
What component of mannitol salt agar makes this medium selective for bacteria in the genus Staphyloccus?
a. mannitol
b. phenol red
c. sodium chloride
d. bile salts
e. agar
c. sodium chloride
Microbiological testing that involves use of 6 foods, 2 inoculum levels of microorganisms, 6 test portions, and 6 negative controls is required to obtain approval from what organization?
a. Food and Drug Administration (FDA)
b. American Type Culture Collection (ATCC)
c. Food Standards Agency (FSA)
d. Organization of Food Safety (OFS)
e. Association of Official Analytical Chemists
e. Association of Official Analytical Chemists
