LAB Microbiology Q&A
In lab we will experimentally prove that UV light does not penetrate which materials. 1) Paper 2) Plastic 3) Glass 4) Metal
1 and 2 Paper and Plastic
How long does the loop have to remain in the incinerator? 1) A full 10 seconds 2) 2-3 seconds but can leave laying in the incinerator longer while preparing other supplies 3) No set time just wait until the loop portion glows red 4) 2-3 seconds if you have not touched anything else
1) A full 10 seconds
Why do we maintain an aseptic environment? 1) Create a safe work environment 2) Minimizes the risk of sample contamination 3) Ensures you maximize the number of microbes you are working with 4) Prevents contamination of yourself and the environment 5) Keeps the environment completely sterile
1) Create a safe work environment 2) Minimizes the risk of sample contamination 4) Prevents contamination of yourself and the environment
A positive VP reaction indicates: 1) Glucose Fermentation 2) Lactose Fermentation 3) Production of 2,3-butanediol 4)Production of Neutral end products 5)Production of acidic end products
1) Glucose Fermentation 3) Production of 2,3-butanediol 4)Production of Neutral end products
When is it important to use aseptic technique? 1) When transferring cultures 2) When obtaining a new isolate 3) When we don't want to contaminate ourselves or others with the microbes 4) When working in a shared lab space
1) When transferring cultures 2) When obtaining a new isolate 3) When we don't want to contaminate ourselves or others with the microbes 4) When working in a shared lab space
The magnification of the ocular lens is? 40X 20X 10X 100X
10X
An obligate psychrophile would produce a turbid culture at ________ degrees Celsius. 60 15 30 45 75
15
A negative stain has chromogen that is ______ charged. This means the stain will be ______ from the cell wall.
1:negatively 2:repelled from
While preparing your smear you did not let the slide dry before heat fixing. As a result when viewed under the microscope after completing staining what would you expect to see. 1) Cells did not absorb the stain due to the excess water 2) Cells would be distorted due to the excess liquid on the slide 3) Cells would look normal as this is the correct procedure 4) Cells will have all washed off since they did not adhere to the slide
2) Cells would be distorted due to the excess liquid on the slide
A broad spectrum antibiotic would be effective on? 1) Fungi 2) Gram Negative Bacteria 3) Gram Positive Bacteria 4) Yeast
2) Gram Negative Bacteria 3) Gram Positive Bacteria
When transferring from one tube to another which actions should you NOT do? 1) Work close to the incinerator or bunsen burner 2) Put caps on the table 3) Keep tubes closed as much as possible 4) Take caps off while in the rack 5) Hold tube in front of the incinerator before and after transfer 6) Hold caps with your little finger and keep the cap pointing down
2) Put caps on the table 4) Take caps off while in the rack
Which statements below apply to differential stains and not to simple stains? 1. Only uses one stain 2. Uses multiple stains 3. Stains all organisms the same 4. Allows you to determine specific characteristics 5. Always requires the slide to be heat fixed 1, 3, 5 1, 3, 4 2, 3, 4 2, 4, 5
2. Uses multiple stains 4. Allows you to determine specific characteristics 5. Always requires the slide to be heat fixed
Which of the following is NOT true? Streak plates can be used to: 1) Estimate if the sample is a pure culture 2) Isolate organisms from a mixture 3) Observe individual cell morphology 4) Observe individual colony morphology
3) Observe individual cell morphology
If you use a 40x objective what is the total magnification? 40x 400x 4000x
400x
You are viewing a specimen in focus at 10x and when you change to the 40x objective the specimen is now slightly blurry. What should you do to ensure you could see your specimen clearly with the new objective? 1) Adjust the stage adjustment knob until the specimen is in the middle of the field of view. 2) Adjust the fine focus until the specimen is sharp and clear. 3) Adjust the course focus until the specimen is sharp and clear. 4) Adjust the stage adjustment knob until the specimen is on the edge of the field of view.
Adjust the fine focus until the specimen is sharp and clear.
You are viewing a specimen in focus at 4x and when you change to the 10x objective you can no longer see it in your field of view. What should you have done before changing objective lens to ensure you could see your specimen? 1) Adjust the fine focus until the specimen is sharp and clear. 2) Adjust the course focus until the specimen is sharp and clear. 3) Adjust the stage adjustment knob until the specimen is on the edge of the field of view. 4) Adjust the stage adjustment knob until the specimen is in the middle of the field of view.
Adjust the stage adjustment knob until the specimen is in the middle of the field of view.
Which classification of bacteria is also called obligate fermenters? Aerotolerant anaerobes Facultative aerobes Obligate aerobes Obligate anaerobes Microaerophiles
Aerotolerant anaerobes
Match the Reagents with their purpose in the Gram Staining procedure. Alcohol Safranin Crystal Violet Iodine Counterstain Primary Stain Decolorizer Mordant
Alcohol- Decolorizer Safranin- Counterstain Crystal Violet- Primary Stain Iodine - Mordant
Organisms that have their optimum growth pH between 8.5 and 11.5 are called...
Alkalophiles
Match the special techniques to experimental set up. A. Anaerobic Jar B. Anaerobic Culture Bottle C. Anaerobic Chamber An ___ works well when you want to take multiple samples over a period of time. An ____ is best for working with very oxygen sensitive samples. An ______ works well for samples that are not as oxygen sensitive and only require a single time point.
An Anaerobic Culture Bottle works well when you want to take multiple samples over a period of time. An Anaerobic Chamber is best for working with very oxygen sensitive samples. An Anaerobic Jar works well for samples that are not as oxygen sensitive and only require a single time point.
Please select all of the statements which are true regarding isolated colonies. An isolated colony is a visible mass that results from the multiplication of a single cell or occasionally a few cells located very closely The cells within a single colony are within the same species Isolated colonies form in liquid nutrient media Isolated colonies can only be obtained via the streak plate method Isolated colonies form on solid nutrient media
An isolated colony is a visible mass that results from the multiplication of a single cell or occasionally a few cells located very closely The cells within a single colony are within the same species Isolated colonies form on solid nutrient media
When performing a endospore stain on an unknown sample you want to ensure that your staining procedure worked correctly. You decide to make a control slide that will be stained at the same time to ensure your results are correct. What would be the best sample to use for the control? Serratia marcescens Bacillus megaterium Staphylococcus aureus Escherichia coli To confirm that your procedure worked correctly what would you expect to see on the control slide? - green endospores - green endospores & pink vegetative cells - only red vegetative cells
Bacillus megaterium green endospores & pink vegetative cells
What is colored by the negative stain? Background surrounding the cell The cell
Background surrounding the cell
What parameters are required based on the organisms' classification as an extreme alkaliphile and halophile. Acidic pH, Low salinity Neutral pH, Low salinity Basic pH, Low salinity Acidic pH, High salinity Neutral pH, High Salinity Basic pH, High salinity
Basic pH, High salinity
Which of the following DNA sequences would be the most likely to be damaged by UV radiation? ATGCACATGA AGGAACGATA CTTGCGCATT CTATACATAG
CTTGCGCATT
In the 1st type of simple stain just described why does the stain adheres to the cells? Cells are negatively charged; stain is basic Cells are negatively charged; stain is acidic Cells are positively charged; stain is acidic Cells are positively charged; stain is basic
Cells are negatively charged; stain is basic
When preparing your smear you forgot to pass the slide over the bunsen burner or flame. Why is this a problem when you move on to staining? 1) Cells will be distorted and morphology can not be correctly visualized 2) Cells will not stick to the slide and will wash off with the staining steps 3) Stain will not be able to enter the cell during the staining process since protein were not denatured
Cells will not stick to the slide and will wash off with the staining steps
You observed after incubation that the tube is yellow and there is no bubble in the durham tube. Using the numbered possible results fill in the table below based on these observations. 1. Positive for fermentation of carbon source 2. Negative Fermentation of Cabon Source 3. Acidic 4. Neutral 5. Basic 6. Positive for gas production 7. Negative for gas production Characteristic Fermentation pH Gas Production
Characteristic Fermentation - Positive for fermentation of carbon source pH- Acidic Gas Production - Negative for gas production
Which statements below are true about the second simple stain discussed. Write T for True and F for false. Increases Contrast Requires excess stain to be removed Multiple stains need to be applied Requires a small drop of stain
Increases Contrast T Requires excess stain to be removed F Multiple stains need to be applied F Requires a small drop of stain T
Which statements are true about how staining techniques help you in the visualization of microorganisms. Write T for True and F for false Increases the magnification of the organism Increase the contrast Increases the resolving power
Increases the magnification of the organism - F Increase the contrast - T Increases the resolving power - F
Determine which statements are true or false when describing a pure culture. Write only T or F for credit not the full word. (Worth 4 Interactions) Consists of only one strain of bacteria A collection of bacteria of the same genus and multiple species An isolated colony on a plate A sample that originated from one person
Consists of only one strain of bacteria - True A collection of bacteria of the same genus and multiple species - False An isolated colony on a plate - True A sample that originated from one person - False
In the endospore stain what is the purpose of the safranin? What is the purpose of the malachite green? Primary stain that stains the endospores red; counterstains the vegetative cells green Basic stain that stains everything purple; primary stain that stains the endospores green Counterstain for the vegetative cells; stains the endospores Mordant that traps the stain in the endospores, counterstain for vegetative cells
Counterstain for the vegetative cells; stains the endospores
If you want to see if an organism is able to metabolize a specific carbon source what type of medium would you use? Complex medium Defined medium
Defined medium
Match the type of medium(numbered) to the correct to the correct goal of the experiment. . 1. Complex 2. Selective 3. Differential 4. Selective and Differential Determine if an isolated organism has a specific characteristic but growth is not dependent on that trait From a mixed sample only grow organisms with a specific characteristic Maximize the number of organisms grown from an environmental sample From an environmental sample grow only specific types of organisms and determine if they have an additional characteristic
Determine if an isolated organism has a specific characteristic but growth is not dependent on that trait - Differential From a mixed sample only grow organisms with a specific characteristic - Selective Maximize the number of organisms grown from an environmental sample- Complex From an environmental sample grow only specific types of organisms and determine if they have an additional characteristic - Selective and Differential
What type of staining procedure is the Gram stain? Basic stain, increases contrast Differential stain, able to determine presence of cell structures Simple stain, allows you to see cells structures Acidic stain, able to see cell shape clearly
Differential stain, able to determine presence of cell structures
What type of staining procedure is the Endospore stain? Why is the technique useful? Basic stain, increases contrast between cells and background Simple stain, allows you to see cells structures Differential stain, able to determine presence of specific cell structures Acidic stain, able to see cell size and shape clearly
Differential stain, able to determine presence of specific cell structures
How do we dilute the culture on the plate? Drag in a single direction from high to low concentration and sterilize the loop between quadrants Sterilize the loop after the original sample is picked up and then only drag from high to low concentration Drag in a single direction from high to low concentration Sterilize the loop between quadrants
Drag in a single direction from high to low concentration and sterilize the loop between quadrants
Why does the loop go back and forth in the 1st quadrant? Dilute the culture in the quadrant Evenly spread the culture To cover the label completely
Evenly spread the culture
In the lab how do we get the culture to start forming spores? Exposure to UV light Exposure to chemicals Exposure to low-nutrient conditions
Exposure to low-nutrient conditions
All staphylococci ar coagulase positive True False
False
Any type of shoes can be worn in the lab. True False
False
Loops should be held in the Bacti-Cinerator for 30 seconds to ensure sterilization. True False
False
The satellite colonies are able to degrade ampicillin True False
False
When a liquid culture contains microorganisms the microbes are always visible to the unaided eye. True False
False
You can observe individual colonies in a broth. True False
False
Why is it recommended that you label on the edge of the plate in the 1st quadrant? Label obscures colony morphology Label does not obscure colony morphology There will be lots of isolated colonies in that quadrant To be consistent
Label does not obscure colony morphology
When labeling the plate shown on the right what was done incorrectly by the student? Label was not on the lid Label was across the middle of the plate Label was on the bottom
Label was across the middle of the plate
Select the sites where microorganisms are likely to be found. (Select all that apply) Laboratory bench surface hands surface of sterile agar inside Petri Dish plate computer keyboard air inside tube of sterile broth
Laboratory bench surface hands computer keyboard air
The course focus is use to make___________ adjustments, while the fine focus is used to make __________ adjustments to the height of the slide. small, large higher, lower Large, small lower, higher
Large, small
During which phase of growth do we calculate the generation time? Lag phase Log phase Stationary phase Death or decline phase
Log phase
After the addition of the reagents nitrate A and B no color change was observed. Zinc was added and the medium immediately turned red. What does this indicate about the organism's ability to reduce nitrate? Positive- reduced nitrate to nitrite Negative Positive-reduced nitrate to a different nitrogen compound Undetermined further testing needed
Negative
Organisms that have their optimum growth pH between 5.5 and 8.0 are called...
Neutrophiles
What class of organisms is likely to inhabit the human body? Psychrophiles Neutrophiles Acidophiles Alkaliphiles Thermophile
Neutrophiles
Will bacteria isolated from a freshwater pond grow equally well in the ocean? Yes No
No
When performing an acidic stain as just described if you rinse off the stain what will you see when the smear is viewed under the microscope? Clear cells and a pale grey background No cells or stain Clear cells and dark grey background
No cells or stain
Organisms that cannot live with oxygen are classified as? Facultative Anaerobe Microaerophile Obligate aerobe Obligate Anaerobe Aerotolerant
Obligate Anaerobe
Steps required to prepare & observe a wet mount Observe the sample with a 40 x total magnification Obtain a clean slide and coverslip Add several loops or drops of a specimen to the center of the slide Draw a target circle on the slide Place cover slip over sample Observe sample at 100x total magnification
Obtain a clean slide and coverslip Draw a target circle on the slide Add several loops or drops of a specimen to the center of the slide Place cover slip over sample Observe the sample with a 40 x total magnification Observe sample at 100x total magnification
When do you use immersion oil and what is its purpose? 1) With the 100x objective; focuses light onto the slide 2) With the 40x and 100x objective; minimizes refraction of light away from lenses 3) On the 100x objective; minimizes refraction of light away from the lens 4) With the 40x and 100x objective; focuses light onto the slide
On the 100x objective; minimizes refraction of light away from the lens
In a simple stain how many dyes are used? One Two Three Four
One
Select the statement that is not true Only organisms that ferment lactose will change the color of the medium when grown on the EMB plate. The EMB plate selects against gram-positive organisms. Organisms that produce a lot of acid during fermentation will produce colonies with a green metallic sheen. Non-fermenting gram negative organisms will grow on the plate and produce colonies without pigmentation.
Only organisms that ferment lactose will change the color of the medium when grown on the EMB plate.
What pipet should I use to most accurately measure 150uL of sample? P20 P100 P200 P1000
P200
Match plate with purpose Positive Control Plate Negative Control Plate Plasmid Inhibition Control Plate Experimental Plate 1. Isolated colonies on LB-AMP 2. Indicates if original competent cells are viable after completion of protocol 3. Lawn of growth on LB 4. No growth on LB-AMP
Positive Control Plate - Indicates if original competent cells are viable after completion of protocol Negative Control Plate - No growth on LB-AMP Plasmid Inhibition Control Plate - Lawn of growth on LB Experimental Plate - Isolated colonies on LB-AMP
Plasmolysis is the ________________ of a bacterial cell membrane in a _____________ solution. Shrinking...........hypotonic Swelling..........hypertonic Swelling..........hypotonic Shrinking.........hypertonic Rupture..........hypertonic
Shrinking.........hypertonic
Why is a microorganism at an advantage if it has hemolysins? - able to invade the host more effectively - able to resist antibiotics more effectively - able to obtain nutrients more effectively - able to evade the hosts defense mechanisms more effectively
able to obtain nutrients more effectively
Pipets have two stop points when depressing the plugger. When used correctly the first stop point is used to ___________ and the second stop point is used to __________. fully expel the sample volume after the transfer, accurately measure the sample volume before aspiration accurately measure the sample, volume before aspiration; fully expel the sample volume after transfer partially expel the sample volume after the transfer, accurately measure the sample volume before aspiration accurately measure the sample volume before aspiration, partially expel the sample volume after transfer
accurately measure the sample, volume before aspiration; fully expel the sample volume after transfer
The addition of ferric chloride to the slant occurs immediately after inoculation, but before placing the slant into the incubator to allow for growth. after incubation and growth is observed on the slant. immediately before inoculation to make it easier to spread the sample on the slant before incubation. when the medium is initially prepared.
after incubation and growth is observed on the slant.
used to decolorize the sample during the gram stain
alcohol
Plasmids used for transformation experiments have selective markers. Which of the examples below is NOT a selective marker. - antibiotic sensitivity - colony color changes - antibiotic resistance - fluorescence
antibiotic sensitivity
A river or pond water sample can contain many types of organisms. Which of the following are most likely to exist and be observable with a bright field microscope. Select all that apply - bacteria algae human cells protozoa virus
bacteria algae protozoa
In a positive citrate test the following are true. The pH of the medium has become more _________, the slant color ___________, and citrate was utilized to produce__________. basic, remained blue, carbon dioxide acidic, turned blue, carbon monoxide basic, remained blue, carbon monoxide acidic, remained blue, carbon dioxide acidic, turned blue, carbon dioxide basic, turned blue, carbon monoxide basic, turned blue, carbon dioxide acidic, remained blue, carbon monoxide
basic, turned blue, carbon dioxide
If an organism is positive for mannitol fermentation the pH of the medium _______ becomes more basic becomes more acidic becomes neutral does not change
becomes more acidic
When completing a quadrant streak, when do you sterilize the loop? (Select all that apply.) before you pick up a loop of the organism from the original culture before you streak quadrant one before you streak quadrants two, three, and sometimes four before you put the loop away
before you pick up a loop of the organism from the original culture before you streak quadrants two, three, and sometimes four before you put the loop away
color of the slide background when stained with nigrosin
black
In a closed system the pH is maintained by incorporating a(n) _______ into the medium. carbohydrate buffer base acid
buffer
Why does less light reach the sensor if cells are present in the sample? cells absorb the light medium absorbs the light cells scatter the light medium scatters the light
cells scatter the light
When observing a wet mount what observation would indicate motility? - cells that move fast or slow in various directions - cells that all slowly move in the same direction - cells vibrate but may remain in place
cells that move fast or slow in various directions
If you did not add storage buffer before placing the cells at -80C what would happen? - cells would continue to grow - cells would burst
cells would burst
To prevent contamination of yourself or your samples you should follow the following rules. Check all that apply. change gloves frequently keep personal items out of the lab workspace keep work surface neat and organized Never touch your face keep cultures in test tube racks when carrying wear safety glasses only if there is a potential for spills
change gloves frequently keep personal items out of the lab workspace keep work surface neat and organized Never touch your face keep cultures in test tube racks when carrying
What would see if after you added malachite green you failed to use moist heat during the staining procedure but completed everything else correctly? red spores, clear or no vegetative cells clear or no spores, red vegetative cells nothing all clear green spores, red vegetative cells green spores, clear or no vegetative cells
clear or no spores, red vegetative cells
When using a basic stain the background will be ___________ and the cells will be ___________. clear, colored clear, clear colored, colored colored, clear
clear, colored
How can you increase the contrast when performing a wet mount? - open the diaphragm - close down the diaphragm - raise the condenser - lower the condenser
close down the diaphragm
A ___ is a mound of cells on a solid medium that represents the progeny from one original bacterial cell.
colony
When using a acidic stain the background will be ___________ and the cells will be ___________. clear, colored colored, clear clear, clear colored, colored
colored, clear
On a light microscope, what do you adjust to properly focus the light onto the specimen? ocular lens fine focus condensor lens objective lens
condensor lens
Which term refers to the introduction of unwanted microorganisms? contamination inoculation ubiquitous sterilization
contamination
What is the purpose of the alcohol? counterstain mordant primary stain decolorize
decolorize
As magnification increases the depth of field will ... remain the same decrease increase
decreases
As the magnification of the lens increases, the working distance ___ remain the same decrease increase
decreases
What is the purpose of the Kirby Bauer test? - determine if an organism produces an antibiotic - determine if an organism is sensitive or resistant to an antibiotic - determine if the organisms require an antibiotic for growth - determine if an antibiotic is sensitive or resistant
determine if an organism is sensitive or resistant to an antibiotic
How are the zones of inhibition (ZOI) measured? - radius of the ZOI in mm - radius of the ZOI in cm - diameter of the ZOI in mm - diameter of the ZOI in cm
diameter of the ZOI in mm
Microorganisms that are able to lyse and one' unable to lyse blood grow on Blood Agar with varying growth patterns. This type of medium would be classified as ______ selective differential complex selective & differential
differential
For each of these methods the end goal is to _________ the original sample until we can see _________. concentrate; isolated colonies dilute; isolated colonies concentrate; lawn of growth dilute; lawn of growth
dilute; isolated colonies
After inoculating a rabbit plasma with an unknown sample and incubating you observe the liquid to be runny. What does this tell you about the organism? - able to use citrate - unable to use citrate - produces coagulase - does not produce coagulase
does not produce coagulase
Why does it take a longer exposure time for all of the Bacillus megaterium to be killed off? gram + gram - cyst former endospore former
endospore former
Blood agar is composed of trypticase soy agar and 5% sheep blood. This agar is defined as ____ because it can be used to grow organisms that are ______ - enriched; fastidious - defined; fastidious - selective; fastidious - enriched; non- fastidious - defined; non- fastidious - selective; non- fastidious
enriched; fastidious
In this set up a tube that has competent cells plus the plasmid is called the _____ tube while the tube that has competent cells and no plasmid is added is called the ____ tube. control; experimental experimental; control standard; test test; standard
experimental; control
If you pick an isolated colony from this plate and restreak it what should you observe on the new plate? only colonies that match the individual colony used to inoculate the plate may only have two of the morphologies observed on the original plate All three different morphologies again isolated on the plate
only colonies that match the individual colony used to inoculate the plate
When performing this inoculation it is important to: use the loop, and make a single straight insertion use the needle, and make a single straight insertion use the loop and swirl while in the tube use the needle and swirl while in the tube use the loop to inoculate the surface and needle to stab cleanly into the tube
use the needle, and make a singlee straight insertion
When you do direct counts with a Petroff- Hausser Counter you count both live and dead cells. True False
true
Microorganisms are found in nearly every environment and are said to be omnipresent contaminated ubiquitous omniscient
ubiquitous
If there is an isolated colony inside of the ZOI then we measure ______ to obtain the correct ZOI value - from the colony to the outer edge of the clearing and double the value - from the colony to the center of the disk and double the value - from the colony to the outer edge of the clearing - from the colony to the center of the disk
- from the colony to the center of the dissk and double the value
To perform aseptic technique correctly which of the following procedures are followed? - petri plate lids are completely removed while inoculating - Loops are rested on the table between usage - loops are sterilized in an incinerator or flame - openings of test tubes are passed by the incinerator or flame just before and after transfer - the table surface is wiped down before and after starting an experiment - talking is minimized while transferring cultures
- loops are sterilized in an incinerator or flame - openings of test tubes are passed by the incinerator or flame just before and after transfer - the table surface is wiped down before and after starting an experiment - talking is minimized while transferring cultures
Why is it easier to determine colony color on the SM110 plate? - media causes cell to produce more pigment - media is clear so color is not obscured by pigmentation of plate
- media is clear so color is not obscured by pigmentation of plate
What is the advantage of using a wet mount? - motility of the specimen can be viewed under a microscope - wet mount is a safer way to view pathogenic organisms - specimen can be viewed as living cells - contrast oof the specimen is enhanced with the addition of water to the slide
- motility of the specimen can be viewed under a microscope - a specimen can be viewed as living cells
Why is Mueller Hinton Medium used when performing Kirby Bauer test? - standard selective growth medium for the assay, better able to visualize thee zone of inhibition, better drug diffusion - standard complex growth medium for the assay, better able to visualize the zone of inhibition, better drug diffusion - standard complex growth medium for the assay, better able to visualize the zone of inhibition, better diffusion of the microorganism - standard selective growth medium for the assay, better able to visualize thee zone of inhibition, better diffusion of the microorganism
- standard complex growth medium for the assay, better able to visualize the zone of inhibition, better drug diffusion
Why do you need to wet the swab in the SM110 broth before taking a sample from the subjects nose? - to ensure microbes will grow in the patients nose - to ensure you pick up more microbes to transfer to the plate - to make sure the swab does not tear the agar plate as the sample is applied - to make sure the swab is sterile before taking a sample
- to ensure you pick up more microbes to transfer to the plate
Why is important to keep the cells cold once they reach an OD of 0.35-0.5? - to stop them from lysing - to stop them from continuing to divide - to keep them growing rapidly - to keep them from gaining competency
- to stop them from continuing to divide
Indicate the statements that correctly describe microbial colonies. (Select all that apply) Microbial colonies are readily observed in broth medium A microbial colony is a visible accumulation of microbial cells on the surface of an agar plate or slant Microbial colonies can be observed intact with a microscope at 1000x magnification A microbial colony is often visualized as an opaque spot on the surface of an agar slant or plate
A microbial colony is a visible accumulation of microbial cells on the surface of an agar plate or slant A microbial colony is often visualized as an opaque spot on the surface of an agar slant or plate
A good control for a Gram stain would consist of: A mixture of known gram positive and gram negative organisms that have different cell shapes A known gram negative organism A known gram positive organism A mixture of known gram positive and gram negative organisms that have the same cell shape
A mixture of known gram positive and gram negative organisms that have different cell shapes
Organisms that have their optimum growth pH between 0.0 and 5.5 are called...
Acidophiles
Why does working close to the bunsen burner flame or an incinerator help to prevent contamination? 1) Hot air kills all the microbes in the air around your work area 2) Hot air rises and carries the microbes in the air away from your work area
Hot air rises and carries the microbes in the air away from your work area
What is released by the gaspak to create an anoxic environment? Nitrogen Carbon Dioxide Hydrogen Peroxide Oxygen Hydrogen Water
Hydrogen
If you forgot to stab into the butt of the tube what characteristic or characteristics would you most likely be unable to determine? Glucose fermentation Lactose fermentation Hydrogen sulfide production Cysteine production Both types of fermentation Glucose fermentation and Hydrogen sulfide production All characteristics
Hydrogen sulfide production
These organisms might grow in the superheated water near hydrothermal vents in the ocean floor
Hyperthermophile
Competent cells are able to take up _____ from the environment - Naked RNA - Naked Protein - Naked DNA
Naked DNA
Both human pathogens and normal microbiota
Mesophiles
Organisms that require lower than atmopsheric levels of oxygen are classified as? Microaerophile Obligate Anaerobe Facultative Anaerobe Aerotolerant Obligate aerobe
Microaerophile
Why does an open tube have a greater chance of contamination? 1) Microbes floating in the air will fall into the tube 2) Microbes from your hands will get transferred to the tube 3) While speaking aerosols from your mouth may enter the open tube
Microbes floating in the air will fall into the tube
Match the terms to the statements that most accurately describe them. Process of purposely adding a microbe to a growth material. The material which provides the nutrients for growth. To cultivate (verb) for the observable growth in or on lab media (noun). Medium Inoculation Culture
Process of purposely adding a microbe to a growth material. Inoculation The material which provides the nutrients for growth. Medium To cultivate (verb) for the observable growth in or on lab media (noun). Culture
These organisms might be isolated from water pools on the surface of a glacier
Psychrophile
What would you see if you forgot to place the slide into the incubator when performing the endospore stain but completed everything else correctly when viewed under the microscope? Red vegetative cells and red spores No cells, everything is clear Green vegetative cells and red spores Red vegetative cells and clear spores inside sporulating cells Green vegetative cells and clear spores
Red vegetative cells and clear spores inside sporulating cells
With viable or spread plate counting there are some disadvantages. Of the options below which one is NOT a disadvantage of the technique. Requires cells to be stained to see viability Requires incubation so is slower Requires lots of supplies Requires knowing the basic growth conditions of the organism
Requires cells to be stained to see viability
Which of these is NOT a reason why the plates and tubes are labeled as instructed. Ensure sample label always remains with the sample Makes it easier to view the sample after incubation Requires your lab notebook to look up the sample ID number
Requires your lab notebook to look up the sample ID number
Which conditions indicate that the environment and media are free of oxygen? Resazurin is pink, Brewers Agar is pink, Methylene blue strip is white Resazurin is clear, Brewers Agar is pink, Methylene blue strip is blue Resazurin is clear, Brewers Agar is clear, Methylene blue strip is blue Resazurin is pink, Brewers Agar is clear, Methylene blue strip is blue Resazurin is clear, Brewers Agar is clear, Methylene blue strip is white Resazurin is pink, Brewers Agar is pink, Methylene blue strip is blue
Resazurin is clear, Brewers Agar is clear, Methylene blue strip is white
When do we "flame" or heat the tube? 1) Right after removing the cap and after insertion of the loop 2) Before the cap is removed and right after the cap is replaced 3) Only right before the loop is inserted 4) Only right after the cap is removed
Right after removing the cap and after insertion of the loop
If you only want to measure the number of viable cells which technique or techniques can be used? Turbidity Petroff Hausser Chamber Spread Plates Turbidity and Spread Plates Turbidity and Petroff Hausser Chamber Petroff Hausser Chamber and Spread Plates
Spread Plates
You should wash your hands before leaving the lab. True False
True
To what depth is the loop inserted? 1) Until the handle just enters the orange portion 2) As far back into the incinerator as possible 3) Just until the loop enters the orange portion
Until the handle just enters the orange portion
Define resolving power 1) The minimum distance between two objects that they can still be observed as one object 2) The minimum distance between two objects that they can still be observed as two separate objects 3) The maximum distance between two objects that they can still be observed as one object 4) The maximum distance between two objects that they can still be observed as two separate objects
The minimum distance between two objects that they can still be observed as two separate objects
When a microorganism is viewed using TEM or SEM you can closely observe the surface. Why does a Gram negative organism appear rough on the surface? The presence of lipopolysaccharides The thinness of the peptidoglycan layer The thickness of the peptidoglycan layer presence of cytoplasmic membrane
The presence of lipopolysaccharides
If multiple colony morphologies are observed from the sample it suggests? The sample has only one type of organism present The sample has more than one type of organism present
The sample has more than one type of organism present
Which of the following may indicate that you have correctly transferred an organism from a pure broth culture to a slant? The slant has colonies and growth of only one color and morphology After gram staining a smear was prepared from the slant, all of the cells have a similar color and morphology under the microscope The slant has colonies of three different colors The slant appears turbid throughout
The slant has colonies and growth of only one color and morphology After gram staining a smear was prepared from the slant, all of the cells have a similar color and morphology under the microscope
In the semi-log graph of CFU/ml vs. time which axis is log scale? x--axis, time X-axis, CFU/ml Y-axis, time Y-axis, CFU/ml
Y-axis, CFU/ml
Please match the type of culture to the statement that most accurately describes it. The type of culture most frequently used in the laboratory which contains only a single species of microorganism A second level culture where an isolated colony from one culture is taken and then transferred into a new medium A culture which contains two or more species A culture which contains one or more unwanted and often unidentified microbes. Contaminated Subculture Pure culture Mixed
The type of culture most frequently used in the laboratory which contains only a single species of microorganism Pure Culture A second level culture where an isolated colony from one culture is taken and then transferred into a new medium Subculture A culture which contains two or more species Mixed Culture A culture which contains one or more unwanted and often unidentified microbes. Contaminated culture
What aspect of the microorganism determines the color of the cells at the end of the Gram Stain procedure. Number of cell membranes Cell shape Thickness of the peptidoglycan layer Thickness of the LPS Presence of endospores
Thickness of the peptidoglycan layer
Microscopes are used to see objects that are __________. Too large to be seen with the unaided eye Too dense to be seen with the unaided eye Too dilute to see with the unaided eye Too small to be seen with the unaided eye
Too small to be seen with the unaided eye
Biological waste must be discarded in a bio-hazard bin. True False
True
Negative staining can be useful for accurately determining the dimension of a cell. True False
True
Blue colored methylene blue strip
indicates oxygen in the anaerobic jar
Generation time is the same for an organism no matter the growth conditions. True False
false
The standard curve of CFU/mL vs. OD once generated can be used for any growth conditions as long as it is the same microorganism. true false
false
When performing the quadrant steak after the first quadrant you should _________. pick up more cells for each remaining quadrant go back and forth in each remaining quadrant to evenly distribute the sample overlap with the two previous quadrants you streaked flame/incinerate the loop between each remaining quadrant
flame/incinerate the loop between each remaining quadrant
In the presumptive test what indicates a positive? gas production turbidity
gas production
Why do we let the cells recover after completing the heat shock step? - give cells time to start expressing the AmpR - begin the selection process for organisms successfully transformed - ensured growth of booth the control & experimental conditions
give cells time to start expressing the AmpR
Pink color resazurin
indicates oxygen is in the medium
If an organism has the enzyme tryptophanase it will reduce tryptophan and produce several end products. When we add Kovac's reagent it turns red due to reacting with? ammonia pyruvic acid tryptophan indole tryptophanase
indole
When performing this inoculation technique each time the plate is rotated to swab a new section the swab is _______ into the original culture. The end goal is to have ______ on the plate after incubation. - not dipped; a lawn of growth - not dipped; isolated colonies - dipped; a lawn of growth - dipped; isolated colonies
not dipped; a lawn of growth
Why would you stab some of the sample into the agar plate? - observe aerobic growth - observe the hemolytic pattern more precisely and slowly - observe anaerobic growth - observe the hemolytic pattern more precisely and quickly
observe the hemolytic pattern more precisely and quickly
What would you see if you forgot to add safranin in the staining procedure but performed all other steps correctly? red spores, clear or no vegetative cells nothing all clear red spores, green vegetative cells clear or no spores, green vegetative cells green spores, clear or no vegetative cells
green spores, clear or no vegetative cells
What is the liquid in the blank? What is the purpose of the blank? water, remove any effects of the liquid so only the cell absorbance is measured Saline, remove any effects of the liquid so only the cell absorbance is measured growth medium, remove any effect of the liquid so only the cell absorbance is measured water, remove any absorbance due to the liquid saline, remove any absorbance due to the liquid growth medium, remove any absorbance due to the liquid
growth medium, remove any absorbance due to the liquid
An eosin methylene blue plate indicates an organism is gram negative and ferments lactose when _____ is observed - no growth is observed - growth of beige colonies - growth of dark purple colonies - growth of grey colonies
growth of dark purple colonies
After streaking an unknown sample on SM110 plate, you observe growth of isolated beige colonies. What does this let you determine about the organism? - ferments mannitol - does not ferment mannitol - halotolerant - non-halotolerant
halotolerant
You inoculated an MA plate with an unknown sample and after incubation you observed growth and yellow medium around the colonies. What does this indicate about the organism? - halotolerant, ferments mannitol - halotolerant, does not ferment mannitol - non-halotolerant, ferments mannitol - non-halotolerant, does not ferment mannitol
halotolerant, ferments mannitol
Salts and sugars work to preserve foods by creating a... lower osmotic pressure. depletion of nutrients. hypertonic environment. hypotonic environment. lower pH.
hypertonic environment.
The main purpose of staining a microorganism is to - preserve the sample for future study - increase the contrast between the organism and the background - adhere the cell to the slide surface - decrease the contrast between the organism and the background
increase the contrast between the organism and the background
When performing this test the reagents are added: into the original broth into an aliquot of the original broth before incubation after 48 hrs of incubation into the original broth after 48 hrs of incubation into an aliquot of the original broth after 48 hrs incubation
into an aliquot of the original broth after 48 hrs incubation
If gas is produced this indicated that the organism has fermented ______? - lactose - mannitol - sucrose - glucose
lactose
In preparing the medium the lab tech forgot to add ampicillin to the plates labeled LB+AMP. What would you expect to see if you plated out the experimental tube? What about your control condition? - lawn of growth on both - lawn of growth; no growth - no growth; lawn of growth - no growth on both
lawn of growth on both
When inoculating a slant surface we move the ________ in a serpentine motion to _________ the medium covered. needle; maximize needle; minimize loop; maximize loop; minimize
loop; maximize
The optimal temperature for growth is closer to the ________ temperature because enzymatic reactions _________ to reach their optimal rate. minimum; speed up minimum; slow down maximum; speed up maximum; slow down
maximum; speed up
Why is it important to prepare a thin smear instead of a thick one? 1) morphology of the cells can be observed 2) Stain evenly penetrates the smear 3) Even distribution of the cells 4) morphology of the colonies can be observed 5) Even distribution of colonies
morphology of the cells can be observed Stain evenly penetrates the smear Even distribution of the cells
What does the term motile mean? - fixed - solid - magnification - moveable
moveable
Unlike the photos on the right side, a sample taken from a positive presumptive test streaked on these plates would likely show _______ after incubation - multiple colony morphologies but all same pigmentation - only one colony morphology and pigmentation - only one colony morphology with different pigmentation - multiple colony morphologies with different pigmentations
multiple colony morphologies with different pigmentations
What is the purpose of the divalent cation? - increase cell membrane charge - decrease cell membrane charge - neutralize cell wall charge - increase permeability of the cell membrane - decrease permeability of cell membrane - neutralize permeability of the cell membrane
neutralize cell wall charge
What location would a hospital routinely sample staff to look for possible MRSA carriers? mouth hands nose
nose
Charge on the chromogen of a basic stain
positive
Based on the figure what aspect of cellular metabolism doe streptomycin target? - cytoplasmic membrane structure - Protein synthesis - DNA gyrase - Folic acid metabolism - cell wall synthesis
protein synthesis
Since the staphylococci are gram positive what color would be observed with microscope after a Gram stain has been completed? red purple
purple
If the staining procedure is done correctly at the end the procedure the vegetative cells should be _________, the endospores will be _________, and the background will be __________. green, red, clear red, green, clear clear, green, red red, clear, green green, clear, red
red, green, clear
Sodium Thioglycollate
reduces free oxygen in medium
Gas Pak
releases hydrogen to reduce oxygen
The numerical aperture is required to calculate the _____ which is the _____ distance two objects can be viewed as separate.
resolving power minimum
If you want to maximize the different types of unknown organisms that would grow from your sample what medium would you choose? Rich medium minimal medium
rich medium
counterstain for the endospore stain
safranin
To get an organism to grow successfully in the lab we have to take into account the original environment. If I want to grow an organism originally from the ocean what condition might be most important. Salinity temperature oxygen pH
salinity
LB medium containing the antibiotic ampicillin would be best described as _______ - enriched - differential - selective
selective
The ZOI for Gentamicin was 19 mm. This indicates that the organism would have what rating? - sensitive - intermediate - resistant
sensitive
The working distance for the 10x objective will be __________ than the working distance with the 4x objective. Larger Smaller the same
smaller
The MPN is a _____ method for determining the number of organisms present within a range. - indirect - direct - statistical
statistical
After the lysis and neutralization steps the tube is centrifuged. What portion is retained? - pellet - supernatant
supernatant
Which statement below is NOT a reason E. coli is used as an indicator of water quality? - rarely found in soil or water unless contaminated - common in the digestive tract of warm-blooded animals - suggests other pathogenic organisms may be present - survives for shorter period of time outside the host body
survives for shorter period of time outside the host body
A positive reaction for the oxidase test is determined by: the paper changing color to purple no color change of the paper the colony changing color to purple no color change in the colony
the colony changing color to purple
Some cells are naturally competent - true - false
true
Why do you not want to prescribe an antibiotic that the microorganism has been shown to have an intermediate rating? - antibiotic is starting to develop resistance indicating that the antibiotic doesn't effectively kill off all the microorganism instead the antibiotic selects for resistant organisms increasing them in the population - a microorganism is starting to develop resistance indicating the antibiotic doesn't effectively kill off all the microorganisms and the antibiotic instead selects for resistant organisms increasing them in the population - microorganism is starting to develop resistance indicating that the antibiotic doesn't effectively kill off all the microorganism and the antibiotic instead selects for organisms that are sensitive to the antibiotic increasing them in the population - antibiotic is starting to develop resistance indicating that the antibiotic doesn't effectively kill off all the microorganisms and the antibiotic instead selects for sensitive organisms increasing them in a population
the microorganism is starting to develop resistance indicating the antibiotic doesn't effectively kill off all the microorganisms and the antibiotic instead selects for resistant organisms increasing them in the population
How is air contamination prevented when an inoculating loop is used to introduce or remove organisms from an agar plate? the plate lid is flamed before insertion of the loop the loop is flamed just before placing the organisms on the plate surface the plate lid is flamed before incubation the plate lid is kept closed or lifted only slightly when inoculating
the plate lid is kept closed or lifted only slightly when inoculating
You have cultured several different objects and surfaces. Which result on an agar plate indicates more diversity obtained from the sample site? the plate with colonies of many different morphologies the plate with the largest colonies the plate with the greatest number of colonies
the plate with colonies of many different morphologies
When a cell is exposed to UV light it causes the formation of ___ which prevent the replication of DNA by inhibiting ____ from working. thymine dimer; DNA polyermase thymine dimer; RNA polyermase thymine duplex; DNA polymerase thymine duplex; RNA polymerase
thymine dimer; DNA polymerase
A quadrant streak can be used for which purpose or purposes below? (Select all that apply.) to determine CFU/mL to estimate the purity of a culture to observe the morphology of colonies to obtain isolated colonies to see the shape of individual cells
to estimate the purity of a culture to observe the morphology of colonies to obtain isolated colonies
A quadrant streak can be used for which purpose or purposes below? (Select all that apply.) to obtain isolated colonies to observe the morphology of colonies to see the shape of individual cells to estimate the purity of a culture to determine CFU/mL
to obtain isolated colonies to observe the morphology of colonies to estimate the purity of a culture
Why is the mouth of a culture tube passed through the Bunsen burned or in front of an incinerator after removing and before replacing the cap? to prevent the entry of ambient air, which might introduce contaminants to heat up the glass to get the culture to temperature for growth to make sure the cap will be easily replaced onto the tube to sterilize the tube
to prevent the entry of ambient air, which might introduce contaminants
Why does each student cover half the plate with an index card? to show normal colony morphology to show a lawn would grow to directly compare exposed vs unexposed growth to indicate if an individual made an error in inoculation to show if any contamination occurred
to show a lawn would grow to directly compare exposed vs unexposed growth to indicate if an individual made an error in inoculation
In the streak plate method, what is the best way to ensure that the loop is cool after it has been sterilized? touch the loop with your finger to determine the temperature touch the loop to an uninoculated portion of the plate touch the loop to an inoculated portion of the plate
touch the loop to an uninoculated portion of the plate
