Microbiology Lab MIDTERM
What is the function of the enzyme citrate lyase? Why would this enzyme be useful in bacteria (think of what pathway it is involved in)?
there is ammonium in the media that are specifically broken down, forming the alkaline end product.
What was the purpose of also inoculating a Nutrient Agar plate in addition to the MSA and EMB plates?
to a make sure the cells were able to grow
Why do you add mineral oil to one of the O/F test tubes (think specifically about the purpose of this test)?
to create an oxygen free environment in the test tube
What is the purpose of the Methyl Red portion of the MRVP test?
to determine if the fermentation end product is acidic
What is the purpose of the Voges Proskauer part of the MRVP test?
to determine the presence of acetoin
Why is the mouth of a culture tube passed through the Bunsen burner flame after removing and before replacing the cap?
to prevent the entry of ambient air, which might introduce contaminants
What is/are the purpose(s) of a performing a simple stain?
to see cell arrangement and morphology
For the fermentation assays, what is the purpose of the Durham (inverted) tubes?
to trap gas produced during fermentation
Microorganisms are found in nearly every environment and are said to be
ubiquitous.
Which of the steps described here prevents the contamination of just-washed hands? - use of a paper towel to turn off a faucet - wetting the hands before applying soap - lathering under running water for 30 seconds - use of hot water
use of a paper towel to turn off a faucet
What is added to the broth for the Voges-Proskauer (VP) Test?
α-napthol and KOH
The Citrate Slant Test determines whether a bacterium:
produces citrate lyase
Gelatin is a large ___________ molecule.
protein
What are three advantages of using the Wet Mount Technique?
quick and easy to repair, can view live organisms, can observe motility.
Nitrate reduction to nitrate is indicated by a ________ color after the addition of nitrate reagent A and B.
red
Nitrate reduction to nitrite is indicated by a ________ color after the addition of nitrate reagent A and B.
red
When preparing pure cultures, dilution is necessary for
reducing the number of inoculated organisms so that isolated colonies can develop.
To retrieve a sample from a culture tube with an inoculating loop, the cap of the tube is
removed and held with the fingers of the loop hand.
Increasing the _____ would allow you to tell if what appears as one object is really two objects very near each other.
resolution
Which of the following is defined as the ability to distinguish fine detail? - resolution - magnification - contrast - media type
resolution
Is a media plate that contains high levels of salt considered differential or selective or both?
selective
Where should you dispose of glass slides, syringes, used scalpel blades, and glass Pasteur pipettes?
sharps container
Which of the following are functions of carbohydrates? (Select all that apply) - catalytic activity - storage of genetic information - storage of energy - structural support - signaling molecules (such as hormones or neurotransmitters)
- storage of energy - structural support
Which of the following items will you need to make a wet mount? - transfer pipette - clean slide - Bunsen burner - timer - tweezers - cover slip
- transfer pipette - clean slide - tweezers - cover slip
Which of the following items should be disposed of in a biohazard bag? (Select all that apply) - used agar plates - glass culture tubes - gloves used while working with infectious microorganisms - paper towels used to clean up a bacterial spill - animal tissue - paper and plastic wraps from sterile swabs, pipettes, and stacks of culture media
- used agar plates - gloves used while working with infectious microorganisms - paper towels used to clean up a bacterial spill - animal tissue
Which of the following conditions may increase the level of microbial contamination in an environment? (Select all that apply) - warm temperature (25°-40°C) - moisture - cold temperature (0°-10°C) - contact with humans and/or other animals
- warm temperature (25°-40°C) - moisture - contact with humans and/or other animals
Which objective lens requires oil to be applied?
100x
The magnification of the ocular lens is
10x.
A total of 199 colonies were counted on the plate that received 1.0 mL of the 1:10,000 dilution of a specimen. What is the bacterial count for the original culture?
1990000 dilution/mL
Cells which contain a thick layer of mycolic acid or cord factor
Acid-fast cells
Microscope: Causes stage (or objective lens) to move upward or downward
Adjustment knob
What are two differences between Aerobic Respiration and Fermentation?
Aerobic respiration uses the presence of oxygen and fermentation does not. Fermentation results in the production of carbon dioxdie.
What is one difference between Aerobic and Anaerobic Respiration?
Aerobic utilizes oxygen as a final e- acceptor
After adding Nitrate Reagents A and B to the bacterium in your nitrate broth, you observe no color change. Does that mean that the bacterium did not reduce nitrate? What is another possible explanation?
After adding nitrate reagents A and B to the bacterium and there is no color change, that means that organism is continuously reducing nitrate to nitrite, and then nitrite to other nitrogen compound. Or it did not reduce nitrate.
What is the decolorizer in a grant stain?
Alcohol/acetone
Which of the following can occur during protein catabolism? - deamination - decarboxylation - desulfhydrase reaction - All of the above
All of the above
Which one of the following can be determined through the results of a Triple Sugar Iron Agar Test? - Fermentation of lactose and sucrose - Fermentation of glucose - Production of hydrogen sulfide - All of the above
All of the above
Which of the following is NOT present in Triple Sugar Iron Agar media? - 0.1% glucose - 1% lactose - 1% sucrose - phenol red indicator - All of the above are included
All of the above are included
Why is the temperature of the liquid agar important when performing serial diluations using the pour plate method? - Bacterial cells will not survive in the agar if the temperature is too high. - The agar will solidify if not kept at a warm temperature. - The agar needs to be in liquid form during the serial dilution steps - All of the above are true.
All of the above are true.
A disinfectant is used on your work surface: - after all work is complete. - All of the answer choices are correct. - before the beginning of laboratory procedures. - after any spill of live microorganisms.
All of the answer choices are correct.
Microscope: Serves as a handle for carrying the microscope
Arm
What biosafety levels do most introductory microbiology students work with?
BSL-1
Why would we look for the production of ferrous sulfide (black precipitate) closer to the bottom of the stab in the Peptone Iron Deeps in order to determine if Hydrogen Sulfide was produced?
Because Hydrogen Sulfide gas is released into the air closer to the media surface and therefore wouldn't produce the ferrous sulfide black precipitate.
Explain why the nigrosin and crystal violet stains requires caution from the student when used in a microbiology lab.
Because it can stain your clothing and can be harmful when it touches your body and eyes.
Which molecule is hydrolyzed (digested) by amylase?
starch
Please choose the answer that best completes the blanks of this sentence in the correct order. The ________ plate method involves spreading an inoculum onto the surface of a plate in a pattern that results in isolated colonies in some areas of the plate after incubation, whereas the ________ plate method involves diluting an inoculum into several melted agar tubes and then adding their contents into plates for solidification and incubation.
streak; pour
Which of them will grow on an EMB plate? Bac A; strong fermenter Bac B; low fermenter Bac C; does not ferment lactose or sucrose
strong fermenter
Polysaccharides are polymers composed of
sugars.
A yellow halo around colonies growing on Mannitol Salt Agar plates means that:
the bacteria are able to ferment mannitol
What do you conclude if your O/F test shows both test tube with and without mineral oil are bright yellow?
the bacteria fements glucose
Which area of the test tube is the best place to observe Hydrogen sulfide production results from a Peptone Iron Deep?
the bottom of the deep
What is gelatinase?
the exo-enzyme that breaks down the protein gelatin in the media
You have cultured several different objects and surfaces in the environment. Which of the following indicates a more abundant bacterial population? - the item with the greatest number of microbial colonies on an agar plate - the item with the largest colonies on an agar plate
the item with the greatest number of microbial colonies on an agar plate
What does it mean if the culture stays the same color after adding Methyl Red reagent to the MRVP broth?
the media is a neutral pH
What would you conclude if the fermentation tube was yellow after 24 hours?
the organism underwent fermentation using the carbohydrate source
Which reagent is used to detect the presence of simple sugars?
Benedict's
Which media is differential? - Nutrient Agar - EMB - Both EMB and MSA - MSA
Both EMB and MSA
1/1points awarded ItemScored Item 1 What was utilized as a pH indicator for the citrate slant?
Bromothymol blue
What was utilized as a pH indicator for the citrate slant?
Bromothymol blue
Which of the following is NOT found in Litmus Milk media? - lactose sugar - Bromthymol blue - milk casein protein - Litmus
Bromthymol blue
What end product of fermentation are you measuring with the respirometer?
CO2
Which type of staining technique do you NOT heat fix the smear prior to staining?
Capsular Stain
Which of the following reagents are used as the primary stain for Acid Fast Stains? - Carbolfuchsin - Malachite Green - Nigrosin - Crystal Violet - Safranin - Methylene Blue
Carbolfuchsin
What are 4 possible end products can be produced during fermentation? Include the organism that undergoes fermentation as well as the fermentative end product.
Carbon dioxide, NADH, lactate acid, ethanol. Streptococcus, lactobacillus, bacillus, saccharomyces.
Which of the following is a positive result for fermentation using the Fermentation Test? - No cell growth and red media - Cell growth and yellow media - Cell growth and orange media - Cell growth and red media
Cell growth and yellow media
Which of the following is a positive result for fermentation using the Fermentation Test? - Cell growth and red media - Cell growth and orange media - No cell growth and red media - Cell growth and yellow media and gas bubbles
Cell growth and yellow media and gas bubbles
Name a clinically important organism which is gelatinase (+)?
Clostridium
What change in litmus milk would occur if excessive amounts of acids were produced?
Coagulation of media would occur
What change in litmus milk would occur if there were very high levels of acid produced following lactose fermentation?
Coagulation of media would occur
Microscope: Concentrates light onto the specimen
Condenser
A culture which contains one or more unwanted and often unidentified microbes.
Contaminated culture
What is the primary stain in a grant stain?
Crystal violet
To cultivate (verb) or observable growth (noun)
Culture
What two amino acids contain Sulfur in their side groups?
Cysteine and methionine
What is a differential media? Explain how is it different from selective media,
Differential media allows growth of different microbes on the same plate. This is different from selective media because selective media suppresses unwanted microbes and encourages desired microbes. Selective media also contains inhibitors which suppress the unwanted microbes.
Clear colonies in an EMB plate
Does not ferment lactose/sucrose
After inoculating and incubating a gelatin deep with an unknown bacterium, you observe that the culture medium has turned liquid. Provide two possible explanations for why the gelatin deep liquified.
Either the gelatin assay was too warm, or the bacteria hydrolyzed the gelatin.
How does the coagulase enzyme function as a virulence factor for Staphylococcus aureus? (How might it help Staphylococcus aureus be more infectious?)
Evade by creating a barrier to prevent immune cells from reaching infection site.
Microscope: Contains a lens at the top of the body tube
Eyepiece (ocular)
T/F A wet mount requires the addition of certain dyes and cell fixatives approximately 12 hours before viewing the specimen.
False
T/F It is important that the smear is thick in order to ensure that the stain will be retained on the slide.
False
T/F Observation of a broth after transfer can show whether or not contamination has occurred.
False
T/F Petri dishes should be incubated with the lid side up.
False
T/F The application of a disinfectant to the lab bench ensures that the work area is sterile before the laboratory exercise is started.
False
T/F The total magnification achieved using a 10× objective lens with a 10× eyepiece lens is 20×.
False
T/F Treating the work area with disinfectant will kill all forms of microbes.
False
T/F Using a cell phone in lab is permissible since it can be used for timing experiments.
False
T/F You may eat a snack in lab as long as there are no bacterial cultures on your bench and you have thoroughly washed your hands.
False
Microscope: Circular area seen through the eyepiece
Field of view
What Gram result would you expect from bacteria that formed green colonies on an EMB plate and were not able to grow on MSA?
Gram -
What is the mordant in a grant stain?
Gram's iodine
Cells which contain both an inner and outer membrane as well as a thin layer of peptidoglyan
Gram-negative cells
Cells which contain a thick layer of peptidoglycan and teichoic acids
Gram-positive cells
What is the color change that indicates a positive citrate test?
Green to blue
Why is negative staining, such as a capsule stain, useful for accurately determining cell size?
Heat fixation is not performed so cells do not shrink.
All of the following are the end products of glycolysis except - NADH. - ATP. - energy. - NAD+. - pyruvate.
NAD+.
You perform an MRVP test to determine the presence of acetoin as an end product of glucose fermentation. Which of the following results indicates that acetoin is present? - Negative Methyl Red, Positive Voges-Proskauer (VP) test - Negative Methyl Red, Negative Voges-Proskauer (VP) test - Positive Methyl Red, Positive Voges-Proskauer (VP) test - Positive Methyl Red, Negative Voges-Proskauer (VP) test
Negative Methyl Red, Positive Voges-Proskauer (VP) test
Which of the following reagents was used for Capsular Staining? - Nigrosin - Malachite Green - Crystal Violet - Methylene Blue
Nigrosin
Streptococcus pyogenes is a gram-positive bacterium. Will it be able to grow on an EMB plate?
No
Would you expect a strictly anaerobic bacterium to be catalase positive? Why or why not?
No because anaerobic organisms do not utilize oxygen and would not form the toxic oxygen species, hydrogen peroxide
Would you expect a bacterium that only carries out fermentation to have a positive oxidase test? Why or why not?
No because fermentation does not utilize the electron transport chain where cytochrome c is present.
What happens if the Methylene Blue step in the acid fast step is omitted?
Non acid fast cells will appear clear, Acid Fast cells will appear red.
Microscope: Part to which the objective lenses are attached
Nosepiece
Microscope: After light passes through the specimen, it next enters this lens system
Objective lens system
What error in the procedure from Exercise #17 could be the reason why you see NO GROWTH on any of the pour plates following the serial dilution from a very turbid, highly concentrated original cell culture?
One reason could be that the agar tubes were heated to a temperature where the bacteria was destroyed.
What is heat fixation?
Passing the slide through the flame of a burner several times after the smear has completely dried.
The type of culture most frequently used in the laboratory which contains only a single species of microbe.
Pure culture
For the pour plate technique, describe what the cell growth on the plates will look like as you serially dilute the initial cell culture into 4 subsequent dilutions.
The cell growth will look less and less as the more plates you pour into. First plate will have the most, second will have less, third will have less, and the fourth will have the least.
T/F All carbohydrates must be converted to glucose to enter glycolysis or fermentation.
True
T/F Inoculated plates are incubated upside down (lid down, agar up) to prevent the dripping of condensate onto the surface of the agar, therefore preventing the dispersal of inoculated organisms.
True
T/F The capsule can be considered a virulence factor and microorganisms containing one are often pathogenic.
True
T/F The dilution factor of a particular bacterial culture made when 30 microliters (μL) is added to 270 μL of sterile broth is the same dilution factor as when 10 milliliters (mL) is added to 90 mL of sterile broth.
True
T/F The formation of a green color after heating with Benedict's reagent indicates that a sample contains simple sugars.
True
Which of the following is NOT considered a positive result for the Nitrate Broth Test? - Turns red only after adding zinc powder - has air/gas in the durham tube - turns red after adding Nitrate reagent A and Nitrate reagent B
Turns red only after adding zinc powder
Why would the production of urease result in the increased pH of the media?
Urease cleaves urea in the media, releasing ammonia (alkaline molecules) from urea
How does smear preparation of cells from a liquid medium differ from preparation of cells from a solid medium?
Water is applied to the slide before emulsifying cells from a solid medium.
What would you conclude from a Triple Sugar Agar test tube that shows a completely yellow media color as well as cracks in the agar?
Yellow media indicates that lactose and sucrose fermentation has occurred and the cracks will indicate carbon dioxide of H2 produciton.
When can you bring food and beverages into the lab?
You are never allowed to do so.
Which of the following is not true of the pour plating method? - you use the technique to estimate bacterial concentration - it can be used to make pure cultures - it can be used to isolate colonies - all of the following are true
all of the following are true
Selective media is the type of media that:
allows for the growth of some organisms by inhibiting the growth of others
When should you wear closed toed shoes in the lab?
always
What is the product of urea hydrolysis?
ammonia and carbon dioxide
What is the smallest unit of a protein?
an amino acid
What is amylase and why was the addition of amylase important for the Benedict Test experiment?
an enzyme that breaks down the polysaccharides into simple sugars. benedict test only detects simple sugars.
For the O/F test, you are looking for the ability of an organism to: - ferment glucose - catabolize peptones - oxidize glucose - any of the above
any of the above
The goal of ______________ technique is to minimize the contamination of both original and newly inoculated cultures as well as to protect the laboratory worker from contamination.
aseptic
What is enhanced when a stain is used to make a sample, or parts of a sample, darker than the background in a slide?
contrast
Staining cells such that their color is different from the background enhances their
contrast.
What does the enzyme coagulase catalyze?
converts fibrinogen into fibrin which forms a clot
A substance used to support the growth of microbial life is referred to as a
culture medium.
The oxidase test is used to detect the presence of
cytochrome c oxidase.
A positive oxidase test is determined by the appearance of a ________ pigment on the oxidase test strip within 30 seconds of adding the bacterial cells.
dark purple
If the color of the nitrate test turns red after the addition of zinc, that means that the bacterium ___________ reduce nitrate.
did not
The Gram stain is an example of a _______ staining procedure, which takes advantage of the fact that cells or parts of cells react differently and can be distinguished by the use of two different dyes.
differential
What incubation temperature is preferred for the growth of most medically important bacteria? (Select all that apply) - 37°C - 25°C - 45°C - 98°F
- 37°C - 98°F
Indicate the statements that correctly describe microbial colonies. (Select all that apply) - A microbial colony is often visualized as an opaque spot on the surface of an agar plate or slant. - A microbial colony is a visible accumulation of microbial cells on the surface of an agar plate or slant. - Microbial colonies are readily observed in broth media. - The cells in an isolated colony are clones all descended from one cell deposited on an agar plate or slant at the time of inoculation.
- A microbial colony is often visualized as an opaque spot on the surface of an agar plate or slant. - A microbial colony is a visible accumulation of microbial cells on the surface of an agar plate or slant. - The cells in an isolated colony are clones all descended from one cell deposited on an agar plate or slant at the time of inoculation.
Which of the following may indicate that you have correctly subcultured an organism from a plate to a slant? (Check all that apply.) - After Gram staining a smear prepared from the slant, all of the cells have similar color and morphology under the microscope. - The slant shows colonies in three different colors. - The slant shows only one color of growth. - The slant appears turbid.
- After Gram staining a smear prepared from the slant, all of the cells have similar color and morphology under the microscope. - The slant shows only one color of growth.
Which of the following may indicate that you have correctly transferred an organism from a broth to a slant? (Select all that apply) - After Gram staining a smear prepared from the slant, all of the cells have similar color and morphology under the microscope. - The slant shows colonies in three different colors. - The slant shows only one color of growth. - The slant appears turbid.
- After Gram staining a smear prepared from the slant, all of the cells have similar color and morphology under the microscope. - The slant shows only one color of growth.
Please select all of the statements that are true about endospores. - Bacterial endospores are highly resistant to heat, drying, and radiation. - Endospores are only found in the environment and are not medically relevant. - Endospores can exist in the environment for indefinite periods of time. - Endospores resist boiling and therefore steam must be used to destroy endospores present in food. - Endospores can be formed by any genus of bacteria.
- Bacterial endospores are highly resistant to heat, drying, and radiation. - Endospores can exist in the environment for indefinite periods of time. - Endospores resist boiling and therefore steam must be used to destroy endospores present in food.
Order the reagents used in the acid-fast staining procedure. - Carbolfuchsin - Acid-alcohol - Methylene blue
- Carbolfuchsin - Acid-alcohol - Methylene blue
Each of the following steps are necessary in preparing and observing a wet mount. Place the steps in the correct order. - Carefully place the cover slip over the drop of specimen. - Observe preparation under the 10X objective lens. - Observe preparation under the 40X objective lens. - Using a transfer pipette, obtain a drop of specimen and place onto the center of the slide. - Obtain a clean slide and cover slip.
- Carefully place the cover slip over the drop of specimen. - Observe preparation under the 10X objective lens. - Observe preparation under the 40X objective lens. - Using a transfer pipette, obtain a drop of specimen and place onto the center of the slide. - Obtain a clean slide and cover slip.
Please order the following choices to reflect the appropriate sequence of materials used in the Gram staining procedure. - Alcohol - Crystal violet - Gram's Iodine - Safranin
- Crystal violet - Gram's Iodine - Alcohol - Safranin
Select the correct uses of the Bunsen burner when aseptically transferring organisms from one medium to another. (Select all that apply) - Flame the mouth of a culture tube before inserting the inoculating loop. - Flame the mouth of an inoculated tube before replacing the cap. - Heat the inoculating loop prior to removal of organisms from the culture tube. - Heat the inoculating loop just before inserting organisms into a sterile medium. - Heat the inoculating loop after transfer before returning loop to holder.
- Flame the mouth of a culture tube before inserting the inoculating loop. - Flame the mouth of an inoculated tube before replacing the cap. - Heat the inoculating loop prior to removal of organisms from the culture tube. - Heat the inoculating loop after transfer before returning loop to holder.
Coagulase is an enzyme that converts fibrinogen into
fibrin
The fine adjustment knob on the microscope - locates the focus plane. - locates the specimen. - fine-tunes the focus. - All of the answer choices are correct.
fine-tunes the focus.
When storing the microscope the stage should be left in the ____ position.
fully down
Which carbohydrate is the primary or preferred starting compound for glycolysis and the fermentation pathway?
glucose
Which of the following is a monosaccharide? - cellulose - glucose - glycogen - starch
glucose
Which of the following is a simple sugar/monosaccharide?
glucose
How is an inoculating loop or needle sterilized prior to use?
holding in the hottest part of the Bunsen burner flame until red-hot
Catalase breaks down ________________ into water and oxygen.
hydrogen peroxide
The color change in a positive citrate test is due to a/an _____________ in pH.
increase
The ________ is an appropriate tool to use for inoculating microorganisms into the butt of an agar slant.
inoculating needle
The phenol red indicator used in the urease test turns pink when the test medium
is basic.
A "pure culture" is one that:
is derived from a single cell
Please choose the answer that best fills in the blanks of this sentence in the correct order. Gram-________ cells stain purple whereas gram-_______ cells stain pink or red when using the Gram stain technique.
positive; negative
Arrange the following steps of applying immersion oil in the correct sequence. - Focus on the specimen using the 40x objective lens. - Rotate the 100x lens over the microscope slide, and use the fine focus adjustment knob to sharpen the image. - Apply a drop of immersion oil directly onto area of the slide you were viewing. - Turn the objectives to half way between the 40x lens and the 100x lens.
- Focus on the specimen using the 40x objective lens. - Turn the objectives to half way between the 40x lens and the 100x lens. - Apply a drop of immersion oil directly onto area of the slide you were viewing. - Rotate the 100x lens over the microscope slide, and use the fine focus adjustment knob to sharpen the image.
Which of the following staining techniques are a type of Differential Stain? - Simple Stain (Methylene Blue) - Gram Stain - Acid Fast Stain - Capsular Stain - Endospore Stain - Flagella Stain
- Gram Stain - Acid Fast Stain
Which of the following are reasons for washing hands before and after lab activities? (Select all that apply) - Hands may be a source of contamination to the lab experiments. - Hands may become contaminated with infectious bacteria during lab experiments. - Hands may become stained during lab. - Hands may be contaminated with irritating chemicals during experiments. - Hand washing will sterilize hands.
- Hands may be a source of contamination to the lab experiments. - Hands may become contaminated with infectious bacteria during lab experiments. - Hands may become stained during lab. - Hands may be contaminated with irritating chemicals during experiments.
Which are advantages of the quadrant streak plate method when compared to the pour plate method? - It requires fewer materials. - It requires less skill. - It is a very quick process. - It does not require the use of heat.
- It requires fewer materials. - It is a very quick process.
What should be done to prepare or deal with a laboratory emergency? (Select all that apply) - Know the location of safety equipment such as the fire extinguisher. - Notify your instructor regarding spills or nonemergency situations. - Call 911 if an emergency occurs. - Take antibiotics regularly before attending class in case of spills. - Conduct all lab procedures under a fume hood.
- Know the location of safety equipment such as the fire extinguisher. - Notify your instructor regarding spills or nonemergency situations. - Call 911 if an emergency occurs.
Place the following steps in order to demonstrate your understanding of the pour plate method. - Incubate for 24-48 hours. - Add loopful of organisms to an agar tube. - Transfer one loopful from one agar tube into another agar tube, and repeat this again with a third agar tube. - Liquefy nutrient agar tubes and maintain at 50 degrees Celsius. - Pour liquefied agar tubes into empty plates. - Remove loopful of organisms from culture using aseptic technique.
- Liquefy nutrient agar tubes and maintain at 50 degrees Celsius. - Remove loopful of organisms from culture using aseptic technique. - Add loopful of organisms to an agar tube. - Transfer one loopful from one agar tube into another agar tube, and repeat this again with a third agar tube. - Pour liquefied agar tubes into empty plates. - Incubate for 24-48 hours.
Which of the following are possible products of nitrate reduction? (Check all that apply!) - Hydrogen sulfide, H2S - Methane, CH4 - Nitrite ion, NO2- - Nitrous oxide, N2O - Nitrogen gas, N2
- Nitrite ion, NO2- - Nitrous oxide, N2O - Nitrogen gas, N2
An acid-fast staining method was performed on a bacterial smear using the dyes carbolfuchsin and methylene blue. The resulting stained slide contained only cells that appeared blue when visualized using a microscope. Which of the following could explain why only blue cells were present? - No acid-fast bacteria are present on the slide - Methylene blue was not used - Carbolfuchsin was not used - Acid-alcohol was not used
- No acid-fast bacteria are present on the slide - Carbolfuchsin was not used
Indicate the correct order of steps as you bring an object into focus under high power. - Rotate to low power objective, then use fine focus to sharpen the image - Turn on the light and center the specimen over the light source. - Place slide on stage and secure with stage clips. - Readjust fine focus under high power to produce the sharpest image. - Focus specimen on scanning objective using coarse focus adjustment - Rotate high power lens into position.
- Place slide on stage and secure with stage clips. - Turn on the light and center the specimen over the light source. - Focus specimen on scanning objective using coarse focus adjustment - Rotate to low power objective, then use fine focus to sharpen the image - Rotate high power lens into position. - Readjust fine focus under high power to produce the sharpest image.
What are two reasons you must heat fix your slide before a simple stain?
- So water does not rinse off all of the bacteria on the slide - to destroy the unwanted bacteria that could alter the microbe
Indicate the correct order of steps for a broth to broth transfer. - Pass mouth of broth tube through Bunsen burner flame and replace cap. Sterilize inoculating loop and return to loop holder. - Remove a loopful of broth culture, pass mouth of broth culture tube through Bunsen burner flame, and replace cap on tube. - Sterilize and cool inoculating loop, remove cap of culture tube, pass mouth of tube through Bunsen burner flame. - Remove cap of sterile broth tube, pass mouth of tube through the Bunsen burner flame, and insert inoculating loop into sterile broth.
- Sterilize and cool inoculating loop, remove cap of culture tube, pass mouth of tube through Bunsen burner flame. - Remove a loopful of broth culture, pass mouth of broth culture tube through Bunsen burner flame, and replace cap on tube. - Remove cap of sterile broth tube, pass mouth of tube through the Bunsen burner flame, and insert inoculating loop into sterile broth. - Pass mouth of broth tube through Bunsen burner flame and replace cap. Sterilize inoculating loop and return to loop holder.
When completing a quadrant streak, when do you flame the loop? (Check all that apply.) - before you pick up a loopful of organisms from the original culture - before you streak quadrant one - before you streak quadrants two, three, and four - before you return the loop to the receptacle
- before you pick up a loopful of organisms from the original culture - before you streak quadrants two, three, and four - before you return the loop to the receptacle
Indicate the correct order of steps for a broth to agar plate transfer. - Lift the lid of the agar plate slightly and streak the loop across the surface of the agar plate. Replace lid. - Sterilize inoculating loop, remove cap of culture tube, and pass mouth of culture tube through the Bunsen burner flame. - Remove a loopful of bacterial culture from the broth tube, pass the mouth of the tube through the Bunsen burner flame, and replace the cap. - Sterilize inoculating loop prior to replacing in loop holder.
- Sterilize inoculating loop, remove cap of culture tube, and pass mouth of culture tube through the Bunsen burner flame. - Remove a loopful of bacterial culture from the broth tube, pass the mouth of the tube through the Bunsen burner flame, and replace the cap. - Lift the lid of the agar plate slightly and streak the loop across the surface of the agar plate. Replace lid. - Sterilize inoculating loop prior to replacing in loop holder.
Indicate the correct order of steps for a broth to agar plate transfer. - Sterilize inoculating loop, remove cap of culture tube, and pass mouth of culture tube through the Bunsen burner flame. - Remove a loopful of bacterial culture from the broth tube, pass the mouth of the tube through the Bunsen burner flame, and replace the cap. - Lift the lid of the agar plate slightly and streak the loop across the surface of the agar plate. Replace lid. - Sterilize inoculating loop prior to replacing in loop holder.
- Sterilize inoculating loop, remove cap of culture tube, and pass mouth of culture tube through the Bunsen burner flame. - Remove a loopful of bacterial culture from the broth tube, pass the mouth of the tube through the Bunsen burner flame, and replace the cap. - Lift the lid of the agar plate slightly and streak the loop across the surface of the agar plate. Replace lid. - Sterilize inoculating loop prior to replacing in loop holder.
Which of the following may act as the final electron acceptor during anaerobic respiration? (Check all that apply!) - Sulfate ion, SO42- - Carbonate ion, CO32- - Oxygen, O2 - Nitrate ion, NO3-
- Sulfate ion, SO42- - Carbonate ion, CO32- - Nitrate ion, NO3-
What are TWO conclusions you can make if after 48hours, you observe that your Fermentation Test is cloudy with bacterial growth and the media is red.
- The bacteria has grown on the peptone - It's acidic due to the alkaline product which raises the pH
Select the statements that represent goals in correct smear preparation. - The cells must be heat fixed to the slide to prevent removal when stain is washed off the slide. - It is important to minimize any artifacts or distortion of the cells for accurate viewing after staining. - Smears must be thick in order to easily take up stains. - Organisms should be killed on the inoculating loop before application to the slide. - Smears must be thin to allow for observation of single cells.
- The cells must be heat fixed to the slide to prevent removal when stain is washed off the slide. - It is important to minimize any artifacts or distortion of the cells for accurate viewing after staining. - Smears must be thin to allow for observation of single cells.
Please select all of the statements which are true regarding isolated colonies. - The colony results from a single cell or a cluster of cells multiplying into a visible mass. - The cells within the colony are all the same species. - Isolated colonies form on solid nutrient media. - Isolated colonies form in liquid nutrient media. - Isolated colonies can only be obtained via the streak plate method.
- The colony results from a single cell or a cluster of cells multiplying into a visible mass. - The cells within the colony are all the same species. - Isolated colonies form on solid nutrient media.
What is the advantage of using a wet mount? - The motility of a specimen can be viewed under a microscope. - The wet mount is a safer way to view pathogenic organisms. - The specimen can be viewed as living cells. - The contrast of a specimen is enhanced with the addition of water to the slide.
- The motility of a specimen can be viewed under a microscope. - The specimen can be viewed as living cells.
After inoculating and incubating an agar slant from a pure broth culture of a bacterial species such as E. coli, which of the following would indicate an unsuccessful aseptic transfer? (Select all that apply) - There is no growth on the slant. - There are red, yellow, and white colonies on the slant. - There are colonies of similar morphology on the slant. - There is fungal growth in the original broth culture tube.
- There is no growth on the slant. - There are red, yellow, and white colonies on the slant. - There is fungal growth in the original broth culture tube.
Which of the following represent important safety procedures for microbiology students? (Select all that apply) - Always wear open-toed shoes so organisms do not become trapped in shoes. - Wash your hands before and after laboratory procedures. - Disinfect your lab bench at the beginning and end of the lab period. - Only drink a closed container of water while conducting lab procedures. - Take extra care around the flame of a Bunsen burner by tying up hair and keeping it from combustibles
- Wash your hands before and after laboratory procedures. - Disinfect your lab bench at the beginning and end of the lab period. - Take extra care around the flame of a Bunsen burner by tying up hair and keeping it from combustibles.
When is it critical to wear gloves in the laboratory? Select all that apply. - You must wear gloves when working with toxic chemicals. - You must wear gloves when performing dissection experiments. - You must wear gloves when working with sterile mammalian cell cultures. - You must wear gloves when washing your hands at the end of the lab.
- You must wear gloves when working with toxic chemicals. - You must wear gloves when performing dissection experiments. - You must wear gloves when working with sterile mammalian cell cultures.
Which types of culture media are solid? (Select all that apply) - agar plates - broth - slants
- agar plates - slants
Indicate the sites where microorganisms are likely to be found. (Select all that apply) - air - laboratory bench surface - hands - surface of sterile agar plate - computer keyboard - inside tube of sterile broth
- air - laboratory bench surface - hands - computer keyboard
Which of the following is a possible mistake when performing a quadrant streak that could lead to no growth beyond the first quadrant? Select all that apply. - beginning the second quadrant streak while the loop is still hot - forgetting to sample from the original culture before beginning the second quadrant streak - forgetting to flame the loop before beginning the second quadrant streak - touching the loop to your bench before beginning the second quadrant streak
- beginning the second quadrant streak while the loop is still hot
Goggles or appropriate safety glasses protect the eyes from (Select all that apply) - chemical splashes - fumes of preservatives used on anatomy specimens. - UV exposure when using UV radiation in the laboratory - burns from the hot plate or Bunsen burner
- chemical splashes - UV exposure when using UV radiation in the laboratory
Which of the following items may be on the laboratory bench top while doing lab work? (Select all that apply) - cultures (broth tubes, agar plates, agar slants) - equipment items specifically needed to complete the lab activity. - backpack, purse - pencil or pen - cell phone
- cultures (broth tubes, agar plates, agar slants) - equipment items specifically needed to complete the lab activity. - pencil or pen
Which of the following items can be washed in the sink after use in the laboratory? (Select all that apply) - dissection tools - glassware that was not used with hazardous chemicals - E. coli broth culture tubes - inoculating loops - dissection trays
- dissection tools - glassware that was not used with hazardous chemicals - dissection trays
Your lab partner has the following items out on the bench. Select all of the following that you should kindly suggest he remove before you begin your lab exercise. - drinking water - granola bar - pencil - lab manual
- drinking water - granola bar
Select all of the following that are products of alcoholic fermentation. - glucose - water - oxygen - ethanol - carbon dioxide - ATP
- ethanol - carbon dioxide
Select all of the following that are microscopic organisms. - fungi - molecules - viruses - bacteria - plants - algae - protozoa
- fungi - bacteria - algae - protozoa
Select all of the following that can be studied with brightfield microscopy. - fungi - molecules - viruses - bacteria - plants
- fungi - bacteria - plants
Select all of the following pathways that produce ATP during cellular respiration. - glycolysis - electron transport chain - Calvin cycle - Krebs cycle - preparatory reaction
- glycolysis - electron transport chain - Krebs cycle
For the Pour Plate method, you used liquid agar. What are TWO reasons why temperature had to be carefully maintained during this experiment because of the liquid agar?
- if the temperature got too cool, the agar would solidify - if the temperature got too hot, the agar would the bacteria would die
Select all of the following that are true statements about fermentation. - lactate may be produced - a large amount of ATP is produced - ethanol may be produced - the reactions happen in the cytoplasm - NADH is produced - the reactions happen in the mitochondria - CO2 may be produced
- lactate may be produced - ethanol may be produced - the reactions happen in the cytoplasm - CO2 may be produced
Select all of the following that are products of lactic acid fermentation. - glucose - water - oxygen - lactic acid - carbon dioxide - ATP
- lactic acid - carbon dioxide
Which of the following items should be disposed of in the Sharps container? (Select all that apply) - needles - glass pipettes - broken glass - gloves - agar plates - scalpel blades
- needles - glass pipettes - broken glass - scalpel blades
Which of the following methods can be used to generate isolated colonies? Select all that apply. - quadrant streak plate method - pour plate method - dilution series plating - optical density reading - butt inoculation of an agar slant
- quadrant streak plate method - pour plate method - dilution series plating
Which of the following steps are part of a thorough hand washing protocol? (Select all that apply) - removal of bracelets, watches, and rings - applying soap prior to wetting hands - lathering with soap, rubbing hands together for at least 20 seconds - using a brush and wooden stick, clean well under finger nails - using paper towels to turn on the faucet
- removal of bracelets, watches, and rings - lathering with soap, rubbing hands together for at least 20 seconds - using a brush and wooden stick, clean well under finger nails
When is it crucial for you to use protective eye wear in the lab? Select all that apply. - when working with corrosive, irritating, or infectious materials that may be a splash hazard - when using a Bunsen burner - when using the microscope - when working with sharp objects
- when working with corrosive, irritating, or infectious materials that may be a splash hazard - when using a Bunsen burner
Which of the following is NOT present in Triple Sugar Iron Agar media? - 1% glucose - phenol red indicator - ferrous sulfate - 1% sucrose - 1% lactose
1% glucose
A total of 145 colonies were counted on the plate that received 1.0 mL of the 1:10,000 dilution of a specimen. What is the bacterial count for the original specimen?
1,450,000 CFUs/mL
A total of 75 colonies were counted on the plate that received 1 mL of a diluted specimen. After calculating, it is determined that the total bacterial count in the original specimen was 75,000,000 colony forming units (CFUs) per mL. What was the dilution factor for the plated sample?
1:1,000,000
How long should hands be lathered while washing?
20 seconds
When performing a Standard Plate Count (SPC), plates that contain ________ colonies are selected for counting with a colony counter.
30-300 colonies
If a specimen was being viewed using a 40x objective and 10x oculars, what would be the total magnification?
400
What lens could get dirty with oil if you move the revolving nosepiece in the wrong direction after viewing under oil immersion?
40x
What is the correct way to open an agar plate to either remove a sample or to inoculate?
?
What result indicates that the bacteria catabolized peptones in the O/F media?
?
Describe a positive lab result for the Citrate Slant Test. Compare with the appearance of a negative result.
A positive citrate slant test will look blue which means that the bacteria was able to utilize citrate and produce ammonia. A negative citrate slant test will look green which means that the bacteria did not utilize the citrate.
Describe a positive VP Test Result.
A positive result will turn red when exposed to oxygen.
What is a "pure culture" and why might we try to obtain a pure culture?
A pure culture is a culture that only contains one type of organism. We might try to obtain a pure culture so we can study the morphological, physiological, and growth characteristics of one type of organism.
What is a clinically important organism that is Urease (+)? What is important about this organisms ability to survive in an extreme environment?
Helicobacter pylori. This organisms ability to survive in an extreme environment is important because it is a common cause of stomach ulcers. because it is urease (+), it is able to produce ammonia which neutralizes the acids in the stomach which allows for it to survive.
For the Peptone Iron Deep Test, describe a positive result and explain how this result is produced in the media.
Hydrogen sulfide reacts with ferric ions in the media and forms ferrous sulfide which will indicate a positive reaction. black precipitatin
What might happen if you allow for the Fermentation test to continue past 24 hours? What could occur that would change your results?
If you observe after the 24 hour mark, the bacteria could start growing on the peptones. It could leave to a false negative. pH will increase as peptones are used.
After focusing on an object with the low power objective lens, you are trying to bring it into focus under the 40x objective lens, but the field of view is very dark. Which of the following may remedy this problem? - Only use lower power magnification. - Add more immersion oil. - Increase the light intensity. - Adjust the fine adjustment knob.
Increase the light intensity.
Process of adding a microbe to a growth material
Inoculation
Microscope: Increases or decreases the light intensity
Iris diaphram
When you inoculated a sterile broth or sterile slant with a bacterial culture you also had a negative control. Describe what the negative control was and its purpose.
It is the same experiment except nothing is changed so it can be used for comparison
Jackie went to the sink at the end of lab to wash her hands. After removing her watch and rings, she turned on the water, wet her hands, added soap and thoroughly rubbed and lathered her hands for 30 seconds, cleaning the backs of her hands, her fingernails, and between her fingers. She then turned off the water, and reached for the paper towels to dry her hands. Identify the correct statement below.
Jackie should have used paper towels to turn off the faucet.
For Lab #18 (Quantitative Dilution of Bacteria), which of the following tools did you use after serially diluting cells, in order to ensure that the volume you added onto the agar plate was able to evenly cover the surface of the plate?
L-spreader
Describe a positive result for the Gelatinase Test.
Liquefication will indicate a positive gelatinase test
Please choose the answer that best completes the blanks of this sentence in the correct order. _______ is used to stain the endospore, and _______ is the stain used to stain the vegetative cell in spore staining.
Malachite green; safranin
What change in litmus milk would occur if acids were produced following lactose fermentation?
Media would turn pink
What change in litmus milk would occur if amino acids were catabolized?
Media would turn purple
The material which provides the nutrients for growth
Medium
Purple colonies in an EMB plate
Medium fermenter of lactose/sucrose
A culture which contains two or more species which can be easily differentiated.
Mixed culture
What is the counterstain in a grant stain?
Safranin
Which of the following is true regarding selective media? - Selective media includes chemicals that prevent the growth of unwanted bacteria without inhibiting the growth of desired organisms. - Selective media contains various nutrients that allow the researcher to distinguish one bacterium from another - Selective media includes certain chemicals that will enhance the growth of desired bacteria over that of the other bacteria - Selective media changes the color of the cells or the media to allow us to learn more about the bacteria
Selective media includes chemicals that prevent the growth of unwanted bacteria without inhibiting the growth of desired organisms.
Microscope: Platform that supports a microscope slide
Stage
Microscope: Holds a microscope slide in position
Stage (slide) clip
Metallic green colonies in an EMB plate
Strong fermenter of lactose/sucrose
A second-level culture where an isolated colony from one culture is taken and transferred into a new medium.
Subculture
What must occur before sucrose is used in cellular respiration?
Sucrase enzyme breaks it down to glucose and fructose.
What environmental factors will affect the type of microbial growth?
Temperature, osmotic pressure, atmospheric gases, ph, and moisture.
What does a change from green media to blue media indicate in the Citrate Agar assay?
That the bacteria has broken down citrate into to pyruvate for use in fermentation
After 2 days you observe a black precipitate in your Peptone Iron deep containing the amino acid cysteine, after it was inoculated with Proteus vulgaris. What could you conclude?
The bacteria has released Hydrogen Sulfide from cysteine
What would you conclude if the media in the Fermentation Test tube turned yellow after 24 hours?
The bacteria was able to ferment glucose
What would you conclude if your Urease Test demonstrated yellow media except for the slant which is brightly fuschia?
The bacterium did not grow well
For the Triple Sugar Iron Agar Test, what would explain in the bottom of the agar being yellow, but the slant turning red?
The bottom being yellow will mean that a small amount of glucose was fermented, and once exhausted, peptones were oxidized which turned the slant portion red due to the alkaline ammonia end products.
When performing an Endospore Stain of a smear of vegetative cells mixed with endospores, you forget to add Safranin. What will your stain look like?
The endospores will stay green and the vegetative cells will remain unstained
What would you conclude from a Triple Sugar Agar test tube that shows a change to yellow at the bottom of the slant, black precipitate and a red slant?
The litter glucose was broken down and after exhaustion, peptones are catabolized which release alkaline ammonium. Also, hyrodogen sulfide is able to react with ferric ions to produce ferric sulfide which will produce black precipitate.
If you transfer bacterial growth from a broth to an agar plate but nothing grows after incubation, what may have occurred?
The loop may have been too hot when making the transfer.
What would the Litmus Milk test look like if the inoculated bacteria was able to ferment lactose?
The media would change to pink
After 2 days you observe a positive result in your Peptone Iron deep after it was inoculated with Proteus vulgaris by evidence of hydrogen sulfide production. Which result would lead you to this conclusion?
The peptone iron deep has black precipitates along the bottom of the stab
What is the purpose of using aseptic technique to transfer bacteria from a culture to sterile media?
The purpose of aseptic technique is to make sure no other bacteria or foreign substances affect the experiment.
Using the respirometer, how can you determine which carbohydrate is used most efficiently by yeast for fermentation?
The solution in the tube with the largest gas bubble has fermented most efficiently
Which type of staining technique could be used on a sample from a patient's coughed up "sputum" to determine if they have Tuberculosis?
The stain needs to be put over steam for the stain to penetrate endospores
What mistake might a student made if only Quadrant 1 of the Quadrant Streak Plate showed growth?
The student didn't go over the previous quadrants when making streaks 2, 3, and 4.
You make a smear of E. coli and then simple stain the slide with methylene blue. If you failed to use correct aseptic technique by not sterilizing the loop before picking up the bacterial sample for the smear, what results may be seen under the microscope?
There may be cells of different shapes, sizes, and arrangements.
What would the Litmus Milk test look like if the inoculated bacteria reduced litmus?
There would be a white color at the bottom of the media tube
What would your Quadrant Streak plate look like if you did not flame the loop between streaks? Why?
There would be no isolated colonies. The flaming allows to get rid of the bacteria on the loop which isolates it.
Which of the following best describes why you perform a quadrant streak plate?
To obtain isolated colonies that are each derived from one bacterial cell
What is the purpose of performing serial dilutions when trying to quantify the bacterial concentration?
To produce as many CFUs as possible on the dilution plates.
After adding Nitrate Reagents A and B to the bacterium in your nitrate broth, you observe no color change. You also do not observe gas in the Durham Tube. What can you conclude? Do you need to proceed with any additional steps?
You can add zinc to the nitrate broth. If it still has no color change, that means that it was able to reduce which can indicate a positive test. If zinc was added and there was a color change to red, that means that there is a negative test; You can add zinc to the nitrate broth. If it still has no color change, that means that it was able to reduce which can indicate a positive test. If zinc was added and there was a color change to red, that means that there is a negative test.
When observing your streak plate result, you find that the 1st streak is very dense with bacterial growth, the 2nd is less dense and the 3rd streak is even less dense. However, the 4th streak is just as dense as the first streak and you failed to get isolated colonies. You do not believe that you have contaminated your loop because you carefully sterilized it between streaks. What other technical error might have occurred?
You could have touched the 1st streak when doing the the 4 streak, this will introduce unwanted organisms in streak 4 and isolated colonies would not be present.
Based on your knowledge of the catalase test, how might you test to see if a patient has catalase deficiency, (which is known as Takahara's disease)?
You could test their blood as a sample for the catalase test.
What additional step is needed during the Endospore stain in order for the stain to penetrate endospores?
You have to fix it with boiling water for the stain to penetrate the endospores
What has to be done to verify that hydrolysis has taken place after growing bacteria in gelatin deeps?
You should look for liquified gelatin after placing the tube in a beaker of ice
What are TWO applications to performing the Serial Dilution Pour Plate Technique for Lab #17 and/or the Serial Dilution Experiment for Lab #18? In other words, why might you want to perform these techniques?
You want to perform the Serial Dilution Pour Plate Technique because it allows you to separate different bacterial species. For the Serial Dilution Experiment, so you can have bacteria that are spread out and easy to count.
After incubating your bacterium in nitrate broth, you observe that the inverted Durham tube contained gas. Would you go on to add Nitrate Reagents A and B? Why or why not?
You would not add the nitrate reagents because the gas is already an indicator that nitrate was reduced to nitrite and then further reduced to nitrogen gas which indicates a positive result.
When preparing a wet mount specimen for viewing, the specimen should be covered with
a coverslip.
What is a bacterial smear?
a thin film or layer of bacteria or other specimen that has been spread across the surface of a glass slide
What environmental condition(s) could cause yeast to carry out fermentation?
absence of oxygen
In the process of nitrate reduction to nitrite, electrons are
added to nitrate
You have a nutrient broth, an agar slant, and an agar plate with bacterial growth in or on each. If you wanted to evaluate the macroscopic appearance of the bacteria growing in or on the medium, which of the cultures would be the best choice?
agar plate
What type of medium provides the best opportunity for growing and observing the morphology of isolated colonies?
agar plates
Media in slants and Petri dishes is solidified by the addition of
agar.
Before heat fixation, a wet smear of bacterial cells on a slide must first be
air-dried.
The mechanical stage upper knob causes the stage to move
back and forth.
Which of the following would be most appropriate for disposal of cultures on agar plates? - biohazard bag or bin - sharps container - normal trash receptacle
biohazard bag or bin
Which color change represents a positive reaction for the presence of sugar using the Benedict's test?
blue to orange
Which of the following O/F test results would demonstrate that an organism is able to ferment glucose? - both test tubes with and without mineral oil are yellow - both test tubes (with and without mineral oil) are blue - test tube without mineral oil is blue, test tube with mineral oil is yellow - test tube without mineral oil is yellow on top, test tube with mineral oil stays blue
both test tubes with and without mineral oil are yellow
What are 4 important components found in one or both of the test tubes used for the O/F Test?
bromothymol blue pH indicator, glucose, tryptone and mineral oil
How should the gas bubble should be read?
by the leading edge
How is a respirometer used to measure fermentation?
by the size of the gas bubble produced
What are some advantages of an organism producing coagulase?
can evade phagoycitosis by creating a barrier
Which gas is produced as a result of fermentation?
carbon dioxide
What cell structure does Gram staining use to differentiate between organisms?
cell wall
Which part of the microscope will be used first to adjust the focus when starting with the lowest power lens?
coarse focus
A ________ is a mound of cells on a solid medium that represents the progeny from one original bacterial cell.
colony
What result indicates that the bacteria oxidizes peptones in the O/F media?
color change to blue
Which term refers to the introduction of unwanted microorganisms?
contamination
Which of the following is NOT TRUE of the cytochrome c molecule? - it is likely found in aerobic or anaerobic organismsIncorrect - it is found along the electron transport chain - it is involved in the movement of electrons - it is an enzyme that triggers the formation of ATP energy from ADP.
it is an enzyme that triggers the formation of ATP energy from ADP.
Which color result does NOT represent a positive reaction for the Benedict's test? - brown - orange - red - light blue - yellow
light blue
The coarse adjustment knob on the microscope - fine-tunes the focus. - locates the focus plane. - All of the answer choices are correct. - locates the specimen.
locates the focus plane.
A change in what component of microscopy influences the apparent size of the objects being viewed?
magnification
Which of the following is defined as the ability make an object appear larger? - magnification - media type - contrast - resolution
magnification
Which of the following is defined as the ability make an object appear larger? - resolution - media type - contrast - magnification
magnification
What is the carbohydrate source in an MSA plate?
mannitol
What does the term motile mean?
movable
The total magnification of an image is determined by ______ the magnification power of the ocular lens and the magnification power of the objective lens used.
multiplying
The purpose of an Acid Fast Stain is to determine the presence of which of the following cell structures? - outer membrane - mycolic acid cell wall - capsule - outer spore coat
mycolic acid cell wall
A _______ stain is one that colors the background surrounding the cell, leaving the cell itself unstained.
negative
In which circumstance is food and/or beverage allowed in the laboratory?
never
If the inverted Durham tube in the nitrate test has an air bubble, what gas was produced?
nitrogen
What would happen if you forgot to add the Counterstain when performing an Acid Fast Stain? (Describe how the different cell types would appear.)
non-acid fast would be clear
Using oil immersion is useful because
oil immersion increases the resolving power of the specimen.
Pouring hydrogen peroxide onto blood causes it to bubble. What gas is in those bubbles?
oxygen
What is the pH indicator used for the Urease Slant Assay?
phenol red
What are 4 important components/ingredients added to the test tubes used for the Fermentation Test?
phenol red indicator, sugar, inverted durham tube, peptone broth
After mixing an unknown bacterium with coagulase plasma, you observe clots in the plasma. You can conclude that the unknown bacterium is ___________ for the enzyme coagulase.
positive
