TAMU BIOL 351 Lab 3 Exam Review
QUESTIONS FULLY SOLVED.
Selective Media - Answer Enhances isolation by inhibiting the growth of some organisms while
encouraging the growth of others
Differential Media - Answer Exposes differences between organisms
Coliforms - Answer - Members of group Enterobacteriaceae
- Main organism: Ecoli
- Produce Acid and Gas from Lactose Fermentation
- Normal Inhabitants of Intestinal Track
- Evidence of Fecal Contamination
Inhibitors - Answer - Make medium selective
- Prevent growth while also allowing growth
Substrates - Answer - Makes medium differential (mostly)
- Differentiates based on ability to preform certain chemical reactions
Indicators - Answer - Make reaction visible
- Dye that changes color as pH changes
- Chemical that reacts with the product that induces a color change
__________ is the preferred source of metabolic activity in bacteria - Answer Fermentation
What is Fermentation? - Answer Ability to obtain energy by oxidizing organic compounds (i.e
carbohydrates)
Organisms that prefer Glucose will use Lactose/Sucrose First (T/F) - Answer False
Fermentation creates ________ by products, which _________ the pH - Answer acid; lowers
How do organisms obtain energy if there is a depletion of carbohydrates or is unable to ferment
carbohydrates? - Answer Breaking down amino acids or peptones
, Breaking down of amino acids produces __________, which __________ the pH - Answer NH3
(ammonia); raises
TSIA - Answer Triple Sugar Iron Agar
TSIA differentiates bacteria based on.... - Answer - Sugar Fermentation
- Sulfur reduction
- Gas Production
TSIA Slant provides _________ & __________ conditions, so the ___________________
method of isolation is used - Answer aerobic; anaerobic; stab and streak
TSIA contains which three sugars? - Answer Glucose, Sucrose, Lactose
Sources of Oxidized Sulfur in a TSIA Slant - Answer - Ferrous Sulfate
- Sodium Thiosulfate
Fermentation Indicator for TSIA Slant - Answer pH indicator: phenol red
Sulfur Reduction Indicator for TSIA Slant - Answer Ferrous Sulfate
TSIA - glucose fermenter ONLY - Answer -Turns yellow everywhere (12 h)
- Turns pink slant (remaining yellow butt) (24 h) because glucose ran out--> metabolizing amino
acids in aerobic part of slant---> raises pH----> pink
TSIA - glucose and lactose and/or sucrose - Answer - Ferment surgars----> lower pH------>
yellow slant and butt
in TSIA, the glucose concentration is ___________ than the concentration of sucrose and
lactose - Answer 10 x less
In TSIA, ferrous sulfate reacts with ____________ to create a black precipitate - Answer
hydrogen sulfide
in TSIA- if there is a black precipitate, _____________ conditions must have been met first -
Answer Acidic (yellow)
QUESTIONS FULLY SOLVED.
Selective Media - Answer Enhances isolation by inhibiting the growth of some organisms while
encouraging the growth of others
Differential Media - Answer Exposes differences between organisms
Coliforms - Answer - Members of group Enterobacteriaceae
- Main organism: Ecoli
- Produce Acid and Gas from Lactose Fermentation
- Normal Inhabitants of Intestinal Track
- Evidence of Fecal Contamination
Inhibitors - Answer - Make medium selective
- Prevent growth while also allowing growth
Substrates - Answer - Makes medium differential (mostly)
- Differentiates based on ability to preform certain chemical reactions
Indicators - Answer - Make reaction visible
- Dye that changes color as pH changes
- Chemical that reacts with the product that induces a color change
__________ is the preferred source of metabolic activity in bacteria - Answer Fermentation
What is Fermentation? - Answer Ability to obtain energy by oxidizing organic compounds (i.e
carbohydrates)
Organisms that prefer Glucose will use Lactose/Sucrose First (T/F) - Answer False
Fermentation creates ________ by products, which _________ the pH - Answer acid; lowers
How do organisms obtain energy if there is a depletion of carbohydrates or is unable to ferment
carbohydrates? - Answer Breaking down amino acids or peptones
, Breaking down of amino acids produces __________, which __________ the pH - Answer NH3
(ammonia); raises
TSIA - Answer Triple Sugar Iron Agar
TSIA differentiates bacteria based on.... - Answer - Sugar Fermentation
- Sulfur reduction
- Gas Production
TSIA Slant provides _________ & __________ conditions, so the ___________________
method of isolation is used - Answer aerobic; anaerobic; stab and streak
TSIA contains which three sugars? - Answer Glucose, Sucrose, Lactose
Sources of Oxidized Sulfur in a TSIA Slant - Answer - Ferrous Sulfate
- Sodium Thiosulfate
Fermentation Indicator for TSIA Slant - Answer pH indicator: phenol red
Sulfur Reduction Indicator for TSIA Slant - Answer Ferrous Sulfate
TSIA - glucose fermenter ONLY - Answer -Turns yellow everywhere (12 h)
- Turns pink slant (remaining yellow butt) (24 h) because glucose ran out--> metabolizing amino
acids in aerobic part of slant---> raises pH----> pink
TSIA - glucose and lactose and/or sucrose - Answer - Ferment surgars----> lower pH------>
yellow slant and butt
in TSIA, the glucose concentration is ___________ than the concentration of sucrose and
lactose - Answer 10 x less
In TSIA, ferrous sulfate reacts with ____________ to create a black precipitate - Answer
hydrogen sulfide
in TSIA- if there is a black precipitate, _____________ conditions must have been met first -
Answer Acidic (yellow)
