Microbiology Lab Final (past pre. lab quizzes)
minimum inhibitory concentration (MIC) is _______ (select all that apply) - what will be determined in the bacterial mutation exercise - the lowest concentration of an antimicrobial that will inhibit visible growth of microorganisms after incubation - the concentration used to look at the. effectiveness of certain antimicrobial. agents - the non lethal concentration of an antimicrobial to kill a mutant
- what will be determined in the bacterial mutation exercise - the lowest concentration of an antimicrobial that will inhibit visible growth of microorganisms after incubation - the concentration used to look at the effectiveness of certain antimicrobial agents
how do you remove an antibiotic disc from the mechanical dispenser? After placing the disc on the plate, make sure to _______.
- with the forceps - gently press the disc slightly into the agar with the forceps
The possibility of observing no cells after adding a heavy inoculum on the staining slide might be because - you forgot to heat fix the smear - you forgot to use primary stain - you forgot to use mordant - you use a hot inoculating loop to add the organism to make a smear
- you forgot to heat fix the smear
Voges-Proskauer test is another name for
VP test
Disposable latex/nitrile gloves
are always to be worn
Microbes that are capable of either fermentation or respiration are called:
facultative anaerobes
The type of metabolism characteristic of strict aerobes is called respiration, whereas _____ is the type characteristic of strict anaerobes - anaerobic respiration - fermentation - inorganic respiration
fermentation
where do resident microbes in the throat obtain their nutrients ? - other microbes inhaled from air - from the food we eat - saliva
from the food we eat
catalase is an enzyme produced by most microorganisms capable of aerobic respiration. Its substrate is ________. - hydrogen sulfide (H2S) - oxygen (O2) - hydrogen peroxide (H2O2) - the superoxide radical (O2)
hydrogen peroxide (H2O2)
Endospores can be observed without using spore staining technique when using
phase contrast microscope
disinfectants are mainly used for what application?
surfaces of non-living materials
the starch plate is positive when?
there is a clear area around the bacteria
you will streak a BHI plate with the following strains: Str-R, Str-S, Str-S+ DNA, and DNA only. what is the purpose of streaking DNA by itself? - to confirm proper aseptic streaking technique - to confirm the DNA could grow - to confirm complete cell lysis - to confirm the presence of the streptomycin resistance gene
to confirm complete cell lysis
The MR test indicated mixed acid production via glucose fermentation (T/F)
true
endospores are comparatively resistant to UV due to minimum to no water content in it. (T/F)
true
every microorganisms has an optimum, a minimum, and a maximum growth temperature (T/F)
true
extremely stringent obligate anaerobes (any exposure to oxygen) cannot grow in agar deeps or anaerobe jars (T/F)
true
fermentation does not require oxygen as a terminal electron acceptor (T/F)
true
milk is white in color because the calcium caseinate present is water insoluble and exists in suspension as a true colloid (T/F)
true
skin cancer in humans is induced by UV (T/F)
true
using only one kind of dye to stain cells refer to simple staining (T/F)
true
after collecting your sample but before inoculating your plate, you need to ___________ so that it is _________ turbid the McFarland Standard
- mx the swab in a tube of sterile water - about equally (similar levels to)
which of the following personal items should be out during a microbiology lab - water bottle -personal writing utensil - food - headphones - cell phones - none of the provided answers
- none of the provided answers
Where do you put your hands to move the microscope from the cabinet?
- one hand at the arm of the scope - one hand at the base of the scope
endospores can be observed without using spore staining technique when using - phase contrast microscope - light microscope - bright field microscope - dark field microscope
- phase contrast microscope
Bacteria are _____ while yeast are _____.
- prokaryotic - eukaryotic
What color does the inoculating loop turn when exposed to the Bunsen burner flame? What parts of the loop turn this color?
- red - loop and the wire (but not the handle)
how do you change from one objective lens to another?
- rotate the revolving nosepiece (black disk above objective lenses)
Which of the following are PPE? - safety class/goggles - hat - gloves - lab coat
- safety glass/goggles - gloves - lab coat
what tool do you use to inoculate a plate to grow a bacterial lawn? - sterile cotton swab - inoculating loop - glass hockey stick - inoculating needle
- sterile cotton swab
what precautions are taken to ensure your culture stays pure? - lean over open cultures to examine them - sterilization growth media before use - use sterile instruments and containers - leave culture open to allow it to "breathe"
- sterilization growth media before use - use sterile instruments and containers
The hand holding the _____ is used to remove the cap from the tube. Was the cap ever placed on the lab bench/work surface?
- the inoculating loop - no, the cap is carefully held the entire time
transient microorganisms are.. - the organisms that form microcolonies on the surface of skin - reside on our gut - are deep seeded in our hair follicles - those which are picked up from the environment and compete with normal flora for nutrients
- those which are picked up from the environment and compete with normal flora for nutrients
when placing the petri plate in the purple box of the UV lamp, the ______ side of the plate should be towards the center and the _________side should be towards the outside
- uncovered - covered
Which of the following are discarded in the regulated medical waste (biohazard): - used agar plates and gloves - used test tubes - paper towels and kimwipes - slides and coverslips
- used agar plates and gloves
____ is a glycosidase that hydrolyzes starch and causes a zone of hydrolysis - amylase - glycosylase - coagulase - cellulose
amylase
_____ is the glycosidase that hydrolyzes starch and causes a zone of hydrolysis
amylase
The. growth of a well suspended microbial culture is accompanied by
an increase in optical density
what is meant when you are asked to "inoculate your culture"
aseptically transfer an organism from one media to another
crystal violet is a
basic dye
DEO agar is - selective - neither selective nor differential - differential - both selective and differential
both selective and differential
To inoculate a slant, you start at the _____of the slant and move to the ______.
bottom of the agar (lowest part of the agar surface) top of the agar
gelatin is made by boiling a protein called ______. this causes the protein to _____
collagen, denature
lysozyme is an
enzyme present in saliva which has an antibacterial property
the enzymes that are made by cells and released into the surrounding medium are called ______ - extracellular enzymes - cellular enzymes - glycolytic enzymes - hydrolyzing enzymes
extracellular enzymes
Human GI tract are an anaerobic environment meaning that there is a lot of oxygen present allowing for certain types of organisms to survive (T/F)
false
It is impossible for a thermophile to survive at human body temperature (37C) even for brief periods (T/F)
false
Sabouraud Dextrose agar is mainly used to grow bacterial colonies (T/F)
false
Simmons' citrate agar is cobalt blue under acidic conditions (T/F)
false
We can use a spectrophotometer to measure the optical density of a culture. This alone can tell us the viable cell number (T/F)
false
You are allowed to have long hair NOT pulled back in class, as long as you are through working (T/F)
false
You need a very large amount of inoculum when making a wet mount (it should be a big chunk on the end of the inoculating loop) (T/F)
false
all microorganisms stain by gram's method (T/F)
false
culture tubes always have liquid media or broth in them (T/F)
false
final dilutions have positive exponents (T/F)
false
hand sanitizer kills all the possible disease causing agents from your hands (T/F)
false
most bacteriophages can infect any bacterial species (T/F)
false
mutations in genetic material do not ever result in mutants that are better suited to a particular environment than the wild type (T/F)
false
photoreactivation occurs only in photosynthetic bacteria (T/F)
false
the coliform test consists of three parts: the presumptive test, the confirmed test, and the completed test. we perform all three of these in our teaching lab (T/F)
false
the lid of the petri plate should remain on during exposure from the UV lamp (T/F)
false
the purpose of a derial dilution and plating is to determine the concentration of viable cells in the last dilution (T/F)
false
Citrate utilization is useful in differentiating enterobacter aerogenes from e. coli, presence of e. coli in a sample indicates ____
fecal contamination
What would be the results of insufficient decolorization when performing the Gram stain?
gram negative organisms may appear gram positive
Saltwater dwelling bacteria can be classified as? - saccharophilic - halophilic - aquaphilic
halophilic
what is the name for the instrument we use to measure the potential alcohol content of our fermenting grape juice/wine? - spectrophotometer - microscope - pH meter - hydrometer
hydrometer
IMViC is a series of tests used to distinguish organisms in the enterobacteriaceae the test involves _____, ______, ________, & ________
indole production test methyl red test voges proskauer test citrate utilization test
When selective agents are added to a media, it ______
inhibit growth of unwanted organisms from a mixture of other organisms
How do you apply the coverslip?
lower the cover at an angle over the dop of water
In regards to temperature preferences, most organisms are ____
mesophiles
in regards to temperatures preferences, most organisms are ______ - mesophiles - halophiles - psychrophiles - thermophiles
mesophiles
gram's iodine in gram staining act as a
mordant
the occurrence of a stable and heritable change in genetic material is called _______
mutation
when you collect a loopful of culture from the stock tube, should you/can you see the inoculum on the loop?
no ( should no be visible).
proteases are extracellular enzymes that hydrolyze proteins to generate - peptides - amino acids -monosaccharides
peptides
if a motile culture is successfully stained, and are found to have two flagella at one end of a rod shaped cell, this is called a __________ flagellar arrangement - neither - amphitrichous - polar - peritrichous
polar
Most bacterial extracellular polymers such as capsules are composed of _______ - polysaccharides - disaccharides - proteins -lipids
polysaccharides
the differential nature of the DEO plate is due to - presence of lactose and pH indicator - presence of pH indicator - presence of deoxycholate - presence of lactose
presence of lactose and pH indicator
in preparing cells for transformation, the donor strain must be lysed in order to - release it's DNA - prepare it to be competent - make it nervous - sterilize the media
release it's DNA
fermentation is one of the two ways that microorganisms derive energy from nutrients in their environment. the other way is called _____
respiration
metabolism in which oxygen is the terminal electron acceptor is called __________, __________ are examples of organisms which only have this type of metabolism - respiration, strict aerobes - fermentation, strict aerobes - respiration, strict anaerobes - respiration, facultative anaerobes
respiration, strict aerobes
The main purpose of staining microorganisms with a simple stain is to ______
see them more easily under a microscope
in any solution, the dissolved material is called the _____, and the fluid on which it is dissolved is called the __________
solute, solvent
an organism which is sensitive to an antibiotic is grown in the lab in a pure culture on a medium with the antibiotic, if we see colonies of the organism growing on the plate then it must have undergone - transposon mutagenesis - spontaneous mutation - x ray induced mutation - natural selection
spontaneous mutation
The surrounding of the cell after a mature spore is formed in a cell is called - mycelium - vegetative cell - sporangium - free spore
sporangium
The main objective of using crystal violet for capsule staining is to - stain the capsule - stain the bacterial cell - stain the bacterial cell and background - all choices are correct
stain the bacterial cell and background
In the event of a dropped or spilled culture, the following procedure is in effect:
the individual. is not to move about or attempt to clean up the spill, instead the individual is to stand still and call for help
a viable number is
the number of cells capable of division on a solid medium
What position should the objective lenses be in to add immersion oil?
the open spot directly over the slide
the coagulase test is diagnostically important because ____
there is a correlation between a positive coagulase test and potential pathogenicity
ultraviolet (UV) radiation causes mutations in DNA by creating ____ dimers. - guanine - adenine - cytosine - thymine
thymine
what is the main purpose of a T-streak? - to observe colony characteristics - to get isolated colonies - to get viable cells counts - to generate large amounts of bacteria for production purposes
to get isolated colonies
in bacterial ________, DNA is transferred from donor to recipient cell as a piece of "naked" DNA - mutation - conjugation - transformation - transduction
transformation
which of the following is not a DNA repair mechanism talked about for the effects of UV radiation exercise? - transmogrification repair - photoreactivation - Dark repair
transmogrification repair
Which of the following is not a term used to classify temperature growth ranges of bacteria
transmogrophilic
What is the best way to handle cultures in this lab?
treat all cultures as if they were of high virulence
Bacteria appears pigmented in the soft-agar deeps due to the presence of - agar - yeast extract - triphenyltetrazolium chloride - p aminobenzaldehyde
triphenyltetrazolium chloride
In this class at 100X magnification, gram positive controls should always appear purple after gram staining (T/F)
true
PCA allows growth of most the microorganism present in the milk sample (T/F)
true
While a microbial culture is growing exponentially, its optical density increases (T/F)
true
You should not wear gloves while heat fixing your slide because gloves are flammable (T/F)
true
all media are at least slightly selective, but not all media a re differential (T/F)
true
before turning off the microscope, you should lower the brightness all the way (T/F)
true
capsules enable bacteria to adhere to surfaces in many natural environments (T/F)
true
control experiments are required to be performed to validate executions of your test experiment (T/F)
true
dilution factors have positive exponents (T/F)
true
the term "turbidity" refers to the effect of light scattering by a colloidal suspension, like a microbial broth culture (T/F)
true
tonicity refers to the normal osmotic pressure extended by body fluids (T/F)
true
we are using a gradient plate because growth of a colony even in the lowest concentration of antibiotic is considered a mutant (T/F)
true
the stab inoculation method will be used when inoculating: - trypticase soy agar deeps - trypticase soy agar plates - trypticase soy broth
trypticase soy agar deeps
the animal protein which is high in amino acid tryptophan is
tryptone
the indole test is used to test for the ability of a microbe to form the amino acid
tryptophan
another term for milky-ness or cloudiness in a broth culture is ________ - turbidity - colony - sediment - suspension
turbidity
Before adjusting the volume of liquid that a pipette can hold, what do you need to do first?
unlock the pipette by moving the volume lock from locked to unlock
How should you dress for the lab?
wear closed toed shoes; and long pants
The possibility of observing no cells after adding a heavy inoculum on the staining slide might be because
you forgot to heat fix the smear
when inoculating a slant with. bacteria, what pattern should the inoculating loop move in?
zig zags
the clear zone that may sound a paper disk containing disinfectant, indicating that the disinfectant is effective to some degree, is called a ______.
zone of inhibition
what does PPE stand for?
Personal Protective Equipment
growth rate measurements must show an increase in numbers or turbidity (T/F)
TRUE
How many drops of water do you add to the smear that you are preparing? Which do you do first, dry the slide on the warmer or heat fix the slide?
- 1 - dry the slide on the slide warmer
How long should the loop cool after flames sterilization? Where does the lid of the T-streak go while the plate is being streaked?
- 10 to 20 seconds - it is held slightly above the plate at an angle (like a clam shell)
how many times do you need to rotate the plate and then swab across entire agar surface ? afterwards, don't forget to ______
- 3 - swab the entire outside edge of the plate
theoretically, adding sugar to your wine should ______ the specific gravity (% potential alcohol) rading, while fermentation _____ the specific gravity reading. - increase, does not affect - increase, decreases - decrease, increases - decrease, does not affect
- increase, decreases
You use an _____ to inoculate agar deeps, which ________
- inoculating needle -lacks a loop and instead ends in a point
indole production is favorable under - aerobic conditions - anaerobic conditions
- aerobic conditions
Which of the following statements about aerosols is true ? - microorganisms rarely inhabit aerosols droplets in the air - it is very difficult to generate aerosols without sophisticated equipment used - aerosols may be composed of liquid or solid particles
- aerosols may be composed of liquid or solid particles
To inoculate an agar deep, insert the tool at the center of the deep _______. Then gently remove the tool by ______.
- all the way to the bottom of the deep - by following the same path as insertion
Which of the following statements is most true about the growth of microorganism in broth cultures? - motility creates turbidity in broth cultures - bacterial growth creates mycelial mats in roth cultures - bacterial growth creates turbidity in broth cultures
- bacterial growth created turbidity in broth cultures
Cells can be considered mitile if they use ___ to tumble or swim (select all that apply) - cilia - brownian movement - flagella
- cilia - flagella
the purpose of a dilution is to - increase the strength of the diluent - decrease the strength of a diluent - increase the strength of a concentrated solution - decrease the strength of a concentrated solution
- decrease the strength of a concentrated solution
what colony characteristics should one consider when describing a colony on a t-streaked plate? select all that apply - elevation - taste - color - size - colony edge - smell - surface appearance
- elevation - color - size - colony edge - surface appearance
How do you mix broth culture before streaking? what side of the plate do you label?
- gently tap the bottom of the table - the dish ( the part that the agar sits in)
select all that apply to antibiotics - have the ability to stop growth or kill other microorganisms - are produced by a microorganisms - are applied to surfaces - are effective against viruses - are effective in very small doses
- have the ability to stop growth or kill other microorganisms - are produced by a microorganisms - are effective in very small doses
When you are finished viewing a slide under 100x oil immersion, what do you do? put the following in order:
1. lower the mechanical stage 2. remove the slide 3. wipe the 100x lens with lens paper 4. rotate the objective lenses to the empty spots
for the exercise on bacterial mutation, you will generate mutations to varying levels of streptomycin. if the highest concentration of streptomycin on your agar plate was 100 uL/mL, which concentration of streptomycin should no growth be expected after transferring a colony to the antibiotic broth? - 150 - 100 - 50 - 0
150 uL/mL
what is the wavelength for UV light source ?
254 nm
plates are listed as TNTC if they have more than _________ colonies, while they are listed as TFTC if they have less than _____ colonies
300, 30
what is the wavelength for black light source?
365 nm
Yeast cells are typically observed under 40X objective. the total magnification of the specimen is
400
When the red blood cells is completely lysed then it is known as - Beta hemolysis - Delta hemolysis - Alpha hemolysis - Gamma Hemolysis
Beta hemolysis
disinfectants and antiseptics can be used for the same purposes (T/F)
False
if the inoculated phenol red tube turned from red to yellow, the bacteria are excreting basic compounds (T/F)
False
the positive hydrogen sulfide test is production of blackness on the culture tube. this is because - H2S is a black colored gas - the microorganism colonies are black - H2S reacts with Fe2+ and produces black precipitate
H2S reacts with Fe2+ and produces black precipitate
the agar used in the kirby bauer test is called - eosin methylene blue agar - t soy agar - MacConkey agar _ Mueller Hinton agar
Mueller Hinton agar
an agar plate that is completely covered on the surface by bacteria is called a? - overgrown plate - bacterial plate - lawn plate
lawn plate
Safety goggles should be worn at all times while working in a microbiology lab (T/F)
True
selective agents are added to the media to inhibit the growth of unwanted microorganisms (T/F)
True
when methyl-red reagent is added to a tube of MR-test tube post 48 Hour incubation, a positive tube will turn red throughout the tube (T/F)
True
Johnny was working in the microbiology lab one afternoon and received a phone call from his Mom. he decided to pull out his phone while in lab and with his gloves still on. Did Johnny spread bacteria to his phone?
Yes
a positive coagulase test is indicated by
a clot formation
a wet mount is best described as:
a method for observing live cells under a microscope, which does not involve staining the organisms
The T-streak is:
a method for separating microbes by spreading them on agar
which of the following is not example of an antiseptic? - iodine - alcohol - detergents - ammonia
ammonia
when agar plates are closed and taped shut, they should be stored with the lid _____
against the table
The methyl red test was made to identify enteric bacteria, so a positive test will appear a bright red color. what is the color of a negative results - slight red - orange - yellow - all choices
all choices
the term "morphology" refers to bacterial cells - size - shape - arrangement - all choices
all choices
when we test water for microbiological safety, we test for the presence of E.coli because - if water contains organisms common to animal intestines, it should not be consumed by humans - it is impractical to test for pathogens individually '- it lives longer in water than intestinal pathogens do - all choices
all choices
What are some challenges with staining cells in order to see their flagella? - the tendency of flagella to detach during staining - differences in flagellin proteins - variations in the dye - all answers are correct
all of the above
When does the inoculating loop need to be sterilized? - after streaking the second section (area 2) - after streaking the third section (area 3) - after streaking the first section (area 1) - before entering the stock culture tube
all of them
Media that contains a wide variety of nutrients and that support the growth of many different kinds of microorganisms are called ______ media
all purpose
What is a pure culture?
contains only one species of microorganism
plasmoptysis occurs when you rapidly ___ the osmotic pressure outside the cell and the cell wall busts and the cells die - increase - decrease
decrease
in the process of diluting and pouring the soft agar containing viruses, the number of viruses _____ along the increasing dilution tubes while remains ______ when pouring on the bacteria seeded plate - decreases, unchanged - increases, decreases - unchanged, decreases - increases, unchanged
decreases, unchanged
The gram stain is a _____ stain
differential
generally differential media is used to
distinguish one type of microorganism from all others in a mixed culture
Heat fixing is an important step in staining because
it kills the microorganism and ensures its attachment on the slide
heat fixing is an important step in staining because - it keeps the stain on the slide - it kills the microorganism on the smear - it destroys the cell wall of microorganism - it kills the microorganism and ensures its attachments on the slide
it kills the microorganism and ensures its attachment on the slide
fermentation in the production of quality wine relies on which of the following microbial populations?
jealousy guarded strains of pure yeast added by the winery
fermentation in the production of quality wine relies on which of the following microbial populations? - jealously guarded strains of pure yeast added by the winery - naturally occurring soil fungi - wild yeast that occurs naturally on grapes
jealousy guarded strains of pure yeast added by the winery
DEO plates contains which sugar?
lactose
a virus is a type of _____. - obligate intracellular parasite - bacteria - ectoparasites
obligate intracellular parasite
Bacterial capsules are: - inside prokaryotic cells - outside prokaryotic cells - inside eukaryotic cells - outside eukaryotic cells
outside prokaryotic cells
a positive test for catalase (CAT) test is the production of bubbles. what are those bubbles? - carbon dioxide - hydrogen peroxide - steam - oxygen
oxygen
Heat fixing a smear refers to
passing a slide with a smear through a flame 2-3 times
The mat of cells formed at the surface of a static broth is called a _____
pellicle
the following are considered chemical antimicrobial agents (select all that apply) - zone of inhibition - penicillin - heavy metals - pinesol
penicillin heavy metals pinesol
sugar fermentation test is usually a - both choices - standard diagnostic procedure used in clinical labs to identify microbes - test used to determine virulence factors of a microorganisms
standard diagnostic procedure used in clinical labs to identify microbes
the coagulase test is primarily used to differentiate between opportunistically pathogenic and nonpathogenic species in genus ______ - bacillus - proteus - staphylococcus - escherichia
staphylococcus
virulence factors refers to
substances that are produced by bacteria which help them infect animal or plant cells
competence refers to the ability of bacteria to - pass a test - be motile in semi solid agar - take up DNA from the environment - contaminate food
take up DNA from the environment
turbidity is...
the cloudiness in a liquid culture
