MBIO 3812 Exam 3 with verified
solutions passed
Differential media contains one or more specific compounds that can... - correct answer ✔✔distinguish
between different bacterial species.
Components in MacConkey agar - correct answer ✔✔neutral red dye and lactose
selective components in Eosin Methylene Blue agar - correct answer ✔✔Eosin Y Dye & Methylne Blue
Dye
T/F: In Hektoen Enteric agar plates, Shigella cannot reduce sulfur but Salmonella can. - correct answer
✔✔true
In Triple Sugar Iron agar, the slant portion of the media provides _________ conditions and the butt
portion of the media provides ________ conditions - correct answer ✔✔aerobic; anaerobic
T/F: E. coli broth is a selective for E. coli when grown at 37C - correct answer ✔✔False
T/F: Lauryl tryptose broth is selective for coliforms that confirms the presence of coliforms - correct
answer ✔✔It is selective for coliforms, but only gives a presumptive determination of coliform presence,
it doesn't confirm it.
In the Multiple Tube Fermentation exercise, how many LTB (Lauryl Tryptose broth) tubes should you
inoculate with each duck pond dilution? - correct answer ✔✔5
T/F: In the MacConkey agar exercise, the plate divided in half will be inoculated with 2 organisms, which
will be inoculated in a zig-zag pattern. - correct answer ✔✔True
, T/F: In the Eosin Methylene Blue agar exercise, you should make sure not to cross-contaminate the two
bacterial species on the plate. - correct answer ✔✔True
T/F: In the Hektoen Enteric agar exercise, you will inoculate one half of the plate with a single line streak
no more than 2 inches long. - correct answer ✔✔False; you'll inoculate both halves of the plate with zig-
zag patterns
T/F: In the Triple Sugar Iron agar exercise, you will inoculate the tubes with an inoculating loop. - correct
answer ✔✔False; inoculating needle
Triple Sugar Iron Agar can determine an organism's ability to ferment... - correct answer ✔✔3 different
sugars as well as its ability to reduce sulfide
T/F: glucose is the only carbohydrate that can be used in glycolysis - correct answer ✔✔False; lactose or
sucrose can also be used
what are the possible end products of fermentation? - correct answer ✔✔gas and acidic compounds
Most enteric bacteria are: - correct answer ✔✔facultative anaerobes
what do certain enteric species use as an e acceptor in the absense of O2? - correct answer ✔✔sulfur
thiosulfate - correct answer ✔✔an e acceptor for specific biochemical pathway for sulfur reduction
what is thiosulfate reduced by and produce? - correct answer ✔✔reduced by thiosulfate reductase;
produces sulfite & H2S.
ferrous sulfide - correct answer ✔✔insoluble black metallic compound produced by ferrous sulfate
conversion
ingredients in TSI agar - correct answer ✔✔low concentration of glucose, high concentration of lactose &
sucrose, sodium thiosulfate, ferrous sulfate and Phenol Red pH indicator
solutions passed
Differential media contains one or more specific compounds that can... - correct answer ✔✔distinguish
between different bacterial species.
Components in MacConkey agar - correct answer ✔✔neutral red dye and lactose
selective components in Eosin Methylene Blue agar - correct answer ✔✔Eosin Y Dye & Methylne Blue
Dye
T/F: In Hektoen Enteric agar plates, Shigella cannot reduce sulfur but Salmonella can. - correct answer
✔✔true
In Triple Sugar Iron agar, the slant portion of the media provides _________ conditions and the butt
portion of the media provides ________ conditions - correct answer ✔✔aerobic; anaerobic
T/F: E. coli broth is a selective for E. coli when grown at 37C - correct answer ✔✔False
T/F: Lauryl tryptose broth is selective for coliforms that confirms the presence of coliforms - correct
answer ✔✔It is selective for coliforms, but only gives a presumptive determination of coliform presence,
it doesn't confirm it.
In the Multiple Tube Fermentation exercise, how many LTB (Lauryl Tryptose broth) tubes should you
inoculate with each duck pond dilution? - correct answer ✔✔5
T/F: In the MacConkey agar exercise, the plate divided in half will be inoculated with 2 organisms, which
will be inoculated in a zig-zag pattern. - correct answer ✔✔True
, T/F: In the Eosin Methylene Blue agar exercise, you should make sure not to cross-contaminate the two
bacterial species on the plate. - correct answer ✔✔True
T/F: In the Hektoen Enteric agar exercise, you will inoculate one half of the plate with a single line streak
no more than 2 inches long. - correct answer ✔✔False; you'll inoculate both halves of the plate with zig-
zag patterns
T/F: In the Triple Sugar Iron agar exercise, you will inoculate the tubes with an inoculating loop. - correct
answer ✔✔False; inoculating needle
Triple Sugar Iron Agar can determine an organism's ability to ferment... - correct answer ✔✔3 different
sugars as well as its ability to reduce sulfide
T/F: glucose is the only carbohydrate that can be used in glycolysis - correct answer ✔✔False; lactose or
sucrose can also be used
what are the possible end products of fermentation? - correct answer ✔✔gas and acidic compounds
Most enteric bacteria are: - correct answer ✔✔facultative anaerobes
what do certain enteric species use as an e acceptor in the absense of O2? - correct answer ✔✔sulfur
thiosulfate - correct answer ✔✔an e acceptor for specific biochemical pathway for sulfur reduction
what is thiosulfate reduced by and produce? - correct answer ✔✔reduced by thiosulfate reductase;
produces sulfite & H2S.
ferrous sulfide - correct answer ✔✔insoluble black metallic compound produced by ferrous sulfate
conversion
ingredients in TSI agar - correct answer ✔✔low concentration of glucose, high concentration of lactose &
sucrose, sodium thiosulfate, ferrous sulfate and Phenol Red pH indicator
