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Microbiology Lab midterm practice Question and answers already passed 2025, Exams of Microbiology

Newcastle UniversityMicrobiology

Microbiology Lab midterm practice Question and answers already passed 2025

Typology: Exams

2024/2025

Available from 07/10/2025

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Microbiology Lab midterm practice Question and answers already
passed 2025
1. Selective Medium
There are ingredients in the medium that
pro- motes growth of one group/species
and in-
hibits another...
-Sugars in medium promotes (encourages)
the growth of Gram Negative bacilli - fecal
coliform (group) bacteria
-Dies in medium inhibits growth of gram
pos-
itive bacteria
2.
Sugars
in
medium
promotes
(encourages)
Gram Negative bacilli - fecal coliform
(group)
the growth of
3.
Dies in medium inhibits
growth of
bacteria
gram
positive
bacteria
4. Differential medium
shows physical ditterences among species
in- oculated in this medium, in other
words.... shows ditterent colors of the
colonies bases
on the ability of each species
to ferment lac- tose: fermenters and slow
fermenters appear
purple or pink; vigorous
lactose fermenters appear green metallic
sheen. Non-lactose
fermenters remain the
color of the bacterium
or take on the
colorization of the medium.
5.
slow lactose fermenters ap- pear
pf3
pf4
pf5
pf8
pf9
pfa
pfd
pfe
pff
pf12
pf13

Partial preview of the text

Download Microbiology Lab midterm practice Question and answers already passed 2025 and more Exams Microbiology in PDF only on Docsity!

passed 2025

  1. Selective Medium There are ingredients in the medium that pro- motes growth of one group/species and in- hibits another... -Sugars in medium promotes (encourages) the growth of Gram Negative bacilli - fecal coliform (group) bacteria -Dies in medium inhibits growth of gram pos- itive bacteria
  2. Sugars in medium promotes (encourages) Gram Negative bacilli - fecal coliform (group) the growth of
  3. Dies in medium inhibits growth of bacteria gram positive bacteria
  4. Differential medium shows physical ditterences among species in- oculated in this medium, in other words.... shows ditterent colors of the colonies bases on the ability of each species to ferment lac- tose: fermenters and slow fermenters appear purple or pink; vigorous lactose fermenters appear green metallic sheen. Non-lactose fermenters remain the color of the bacterium or take on the colorization of the medium.
  5. slow lactose fermenters ap- pear

passed 2025 purple or pink

  1. vigorous lactose fermenters appear green metallic sheen
  2. What is the color of Non-lactose fer- menters?

passed 2025

  1. vibrio curved rod, comma shaped

passed 2025

  1. spirillum spiral shaped bacteria
  2. gram negative color pink
  3. Gram Negative Gram reaction? positive or negative?
  4. gram positive color purple
  5. bacillus Bacterial morphology
  6. Order of chemicals in a gram stain 1) Crystal Violet
    1. Iodine

passed 2025 Stain all cells purple (primary stain) Gm+ = purple Gm- = purple

  1. Iodine mordant -will merge with the crystal violet inside the cells and form insoluble crystal violet iodine complex in gram positive cells Gm+ = purple Gm- = purple
  2. 95 % Alcohol (EtOH) Decolorize all gram negative cells -it washed away the primary stain of other bacteria except gram positive Gm+ = purple Gm- = colorless
  3. Safranin Counterstain. Turns gram negative cells pink Gm+ = purple Gm- = pink
  4. glucose negative Remain red
  5. glucose positive orange/yellow
  6. If the glucose layer is shiny .... the the gas is positive

passed 2025

  1. lysine negative yellow
  2. lysine positive purple/blue
  3. ornithine negative yellow
  4. ornithine positive purple/blue

passed 2025

  1. dulcitol positive yellow or black
  2. urea negative yellow
  3. urea postitive bright pink

passed 2025

  1. citrate negative green
  2. citrate postitive blue
  3. In a citrate utilization test, the growth of bacteria and usual conversion of the medium from a to a col- or is a "citrate utilization test" re- sult. This change is color in the medium only occurs when the pH. This test determines the ability of an organism to use as its sole source of .
  4. After adding Kovac's Reagent to the SIM Medium, what color indicates a positive Indole test?
  5. The SIM Medium also allows testing for Sulfur Reduction, and a positive result is identified by a that is produced in the semi-solid medium Green Blue Positive increases Citrate Carbon Cherry red Black precipitate
  6. In a Phenol Red Fermentation Test, a pos- Yellow itive result is indicated by what color?

passed 2025

  1. endospore stain A ditterential stain used to detect the pres- ence and location of spores in bacterial cells.
  2. 3 colony shapes circular irregular punctiform
  3. 4 margin types entire (smooth with no irregularities) Irregular (wavy) on outside lobate (hills) filamentous (filled with strings) rhizoid (branches)
  4. 5 Elevation flat raised (square) convex (round) plateau (round then flat) umbonate (looks like bonnet)

passed 2025

  1. 4 different optical properties opaque translucent transparen t clear
  2. how does a colony develop

passed 2025 differentiating bacteria

  1. In fermentation, the specific end product depends on what two things glucos e lactose Maltos e mannitol sucros e
    1. characteristics of fermenting agent- type of organism

passed 2025

  1. condition of the fermentation- media used, pH ect.
  1. What color is an uninoculated medium red
  2. What color is the medium after the fer- mentation of carbohydrates yellow
  3. SIM media sulfur reduction -indole reduction- motility
  4. What are two major things SIM media test 1) ability of a bacterium to reduce sulfur for
  5. What does positive results look like for SIM media tests
  6. What enzyme does a bacterium need in order to produce indole
  7. What substrate is broken down to pro- duce indole
    1. produce indole from tryptophan utilization it will have bubbles and the tube will be black tryptophanage tryptophan
  8. how do you determine if indole is present Add kovac's reagent. The red dye called rosin- in the media
  9. What is the difference between MR and the VP test since they both use the same media?

passed 2025 Simmon's Citrate Media: What color is the medium that is positive for citrate utiliza- tion?

  1. Simmon's Citrate Media: Explain why the medium changes color if an organism is able to utilize citrate Simmons citrate contains sodium citrate as the cole source of carbon, ammonium di-hy- drogen phosphate as the sole source of ni- trogen, other nutrients, and the pH indicator bromthymol blue