BIOL 351 LAB EXAM 3 QUESTIONS AND
ALL CORRECT ANSWERS.
Biochemical Tests - Answer differentiate and identify microorganisms based on specific
biochemical characteristics
Selective Media - Answer - Mixed culture must be isolated and cultivated as pure cultures
before they can be tested and identified
- designed to enhance isolation by inhibiting growth of some organisms while encouraging
growth of others
Differential media - Answer many types of media that may also contain indicators to expose
differences between organisms
Coliforms - Answer subgroup of enterobacteriaceae that produce acid and gas from lactose
fermentation
- e. coli is the most prominent member
Coliforms are normal inhabitants of the ____ - Answer human intestinal tract
Inhibitors - Answer - make medium selective
- designed to prevent growth of specific groups of microorganisms while allowing other
organisms to grow
Substrates - Answer - almost always what makes the medium differential
- differing abilities to perform a specific chemical reaction differentiates organisms
Indicators - Answer - make expected reaction visible
- dye that changes color as pH changes
- can be chemicals that react with products of a reaction and produce a color change
, Fermentation - Answer - preferred source of metabolic activity
- Process of extracting energy from the oxidation of organic compounds such as carbohydrates
- produces acid byproducts lowering the pH
Organisms capable of fermenting glucose will _______ - Answer exhaust glucose supply before
utilizing sucrose or lactose
When carbohydrates are depleted/when microbes are incapable of carbohydrate fermentation
______ - Answer microbes utilize peptones or amino acids
produces NH3, raising the pH
TSIA differentiates bacteria based on - Answer - sugar fermentation: glucose, sucrose/lactose
- sulfur reduction
- gas production
How is TSIA inoculated? - Answer stab in the end followed by fishtail streak of the slant
What does TSIA contain? - Answer glucose, sucrose, lactose
ferrous sulfate and sodium thiosulfate as sources of oxidized sulfur
TSIA fermentation pH indicator - Answer Phenol red
TSIA sulfer reduction indicator - Answer ferrous sulfate
When TSIA is inoculated with a glucose ONLY fermenter: - Answer - produces acid which turns
medium yellow
- glucose is depleted quickly
ALL CORRECT ANSWERS.
Biochemical Tests - Answer differentiate and identify microorganisms based on specific
biochemical characteristics
Selective Media - Answer - Mixed culture must be isolated and cultivated as pure cultures
before they can be tested and identified
- designed to enhance isolation by inhibiting growth of some organisms while encouraging
growth of others
Differential media - Answer many types of media that may also contain indicators to expose
differences between organisms
Coliforms - Answer subgroup of enterobacteriaceae that produce acid and gas from lactose
fermentation
- e. coli is the most prominent member
Coliforms are normal inhabitants of the ____ - Answer human intestinal tract
Inhibitors - Answer - make medium selective
- designed to prevent growth of specific groups of microorganisms while allowing other
organisms to grow
Substrates - Answer - almost always what makes the medium differential
- differing abilities to perform a specific chemical reaction differentiates organisms
Indicators - Answer - make expected reaction visible
- dye that changes color as pH changes
- can be chemicals that react with products of a reaction and produce a color change
, Fermentation - Answer - preferred source of metabolic activity
- Process of extracting energy from the oxidation of organic compounds such as carbohydrates
- produces acid byproducts lowering the pH
Organisms capable of fermenting glucose will _______ - Answer exhaust glucose supply before
utilizing sucrose or lactose
When carbohydrates are depleted/when microbes are incapable of carbohydrate fermentation
______ - Answer microbes utilize peptones or amino acids
produces NH3, raising the pH
TSIA differentiates bacteria based on - Answer - sugar fermentation: glucose, sucrose/lactose
- sulfur reduction
- gas production
How is TSIA inoculated? - Answer stab in the end followed by fishtail streak of the slant
What does TSIA contain? - Answer glucose, sucrose, lactose
ferrous sulfate and sodium thiosulfate as sources of oxidized sulfur
TSIA fermentation pH indicator - Answer Phenol red
TSIA sulfer reduction indicator - Answer ferrous sulfate
When TSIA is inoculated with a glucose ONLY fermenter: - Answer - produces acid which turns
medium yellow
- glucose is depleted quickly
