Spring Midterm Flashcards

Slides, scalpels, razor blades, cover glasses, and capillary tubes are all classified as

• electrical hazards
• hazardous chemicals
• infectious agents

Which of the following would be most appropriate for disposal of cultures on agar plates?

• normal trash receptacle
• biohazard bag or bin
• sharps container

The purpose of lab safety rules and protocols is to

• ensure that the lab activities always produce the expected results
• protect everyone in the lab from injury and infection
• enable students to complete lab assignments and activities in less time
• ensure that the lab stays clean and orderly

Laboratory instruments are sterilized prior to reuse by __________.

• gassing with ethylene oxide
• incineration
• autoclaving
• soaking in disinfectant

The best source of information regarding the hazards posed by any chemical and specific handling instructions is the

• lab partner
• GOOGLE
• lab manual

Which of the following is defined as the ability make an object appear larger?

• contrast
• media type
• magnification
• resolution

Which of the following items will you need to make a wet mount?

• transfer pipette
• clean slide
• bunsen burner
• timer
• tweezers
• cover slip

What is enhanced when a stain is used to make a sample, or parts of a sample, darker than the background in a slide?

• media type
• resolution
• contrast
• magnification

Which of the following is defined as the ability to distinguish fine detail?

• contrast
• resolution
• media type
• magnification

Which objective lens provides the highest total magnification?

• scan
• high power
• low power
• oil immersion

Which of the following must be visually studied using electron microscopy?

• fungi
• viruses
• prokaryotes
• eukaryotes

Which of the image quality factors is usually expressed in a number such as 40x?

• resolution
• contrast
• magnification
• media type

Which metric unit is most appropriate for expressing the size of bacterial cells?

• centimeter
• nanometer
• micrometer
• meter

Select all of the following that are factors affecting the clarity of a microscopic image.

• slide material
• resolution
• contrast
• magnification

Arrange the following steps of applying immersion oil in the correct sequence.

• Rotate the 100x lens over the microscope slide, and use the fine focus adjustment knob to sharpen the image.
• 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.
• Focus on the specimen using the 40x objective lens.

What does the term motile mean?

• magnification
• solid
• fixed
• movable

Which of the following must be visually studied using microscopy?

• fungi
• eukaryotes
• prokaryotes
• plants

Each of the following steps are necessary in preparing and observing a wet mount. Place the steps in the correct order.

• obtain a clean slide and cover slip
• observe preparation under 10X objective lens
• using a transfer pipette, obtain a drop of specimen and place onto the center of the slide
• observe preparation under the 40X objective lens
• carefully place the cover slip over the drop of specimen

The magnification of the ocular lens is

• 1x
• 100x
• 10x
• 40x

Select all of the following that can be studied with brightfield microscopy.

• fungi
• molecules
• viruses
• bacteria
• plants

If a specimen was being viewed using a 20x objective lens and 10x ocular lens, what would be the total magnification?

• 2000x
• 30x
• 200x
• 210x

Which of the following is defined as the ability to distinguish an object from the background?

• media type
• resolution
• magnification
• contrast

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.

All three factors affecting image quality can be controlled by manipulating the microscope.

• True
• False

Pond water can contain many types of organisms. Which of the following are you most likely to find in a pond water sample? Please select all that apply.

• bacteria
• algae
• rotifers
• human cells
• protozoa
• virus

A wet mount requires the addition of certain dyes and cell fixatives approximately 12 hours before viewing the specimen.

• True
• False

Which objective lens requires oil to be applied?

• 10x
• 4x
• 100x
• 40x

Increasing the _____ would allow you to tell if what appears as one object is really two objects very near each other.

• resolution
• media type
• magnification
• contrast

When preparing a wet mount specimen for viewing, the specimen should be covered with

• another glass slide
• a coverslip
• clean paper
• transparent tape

The lenses of a brightfield microscope are responsible for the _____ of the object you are viewing.

• color
• contrast
• media type
• magnification

What is the correct way to open an agar plate to either remove a sample or to inoculate?

• Remove the lid completely, holding it in your hand, not setting it on the bench.
• Open lid slightly on one side, in a clamshell fashion.
• Remove the lid completely and set it on the bench in an upright position.
• Remove the lid completely and set it on the bench upside down.

Which types of culture media are solid? (Select all that apply)

• agar plates
• broth
• slants

1. Process of adding a microbe to a growth material
2. The material which provides the nutrients for growth
3. To cultivate (verb) or observable growth

• culture
• inoculation
• media

How is an inoculating loop or needle sterilized prior to use?

• soaking in 95% ethyl alcohol for several minutes and allowing to air dry
• dipping into a beaker of boiling water
• holding in the hottest part of the Bunsen burner flame until red-hot
• exposure to UV radiation for 15 seconds

What type of media provides the best option for obtaining a culture with isolated bacterial colonies?

• broths
• slants
• plates

A substance used to support the growth of microbial life is referred to as a

• water
• culture medium
• inoculating loop
• incubator

Why is 35-37 degrees Celsius a standard incubation temperature range for many lab exercises involving medically important bacteria?

• This range is energy-efficient.
• This range is close to human body temperature, a temperature preferred by many of these organisms.
• This range is cooler than room temperature, protecting the organisms from death.
• This range denatures the enzymes that make these organisms pathogenic.

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

What term is used to describe the cloudiness produced by bacterial growth in a tube of broth?

• precipitation
• colonies
• particulation
• turbidity

Put the following steps in order to indicate a correct transfer from a bacterial culture to a sterile agar slant.

• Heat loop before returning to its receptacle.
• Remove a small amount of bacteria, heat the mouth of tube, and replace cap.
• Remove the cap from the sterile slant and heat mouth of tube.
• Streak the sterile slant surface with the loop.
• Heat mouth of newly inoculated slant tube and replace cap.
• Heat inoculating loop, remove cap of bacterial culture, and heat mouth of tube.

The lab bench is treated with a disinfectant at what points in the lab exercise?

• before work begins
• after work is finished
• between each separate transfer
• between glove changes

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 incubation.
• The plate lid is kept closed or lifted only slightly when inoculating.
• The plate lid is flamed before insertion of the loop.
• The loop is flamed just before introduction of organisms onto the plate surface.

Environments with ________ temperatures are likely to show more bacterial growth on an exposed agar plate.

• colder
• warmer

The cloudy growth seen in a broth culture is referred to as the ________ of the culture.

• synthetic extract
• precipitate
• nonsynthetic particles
• turbidity

Media in slants and Petri dishes is solidified by the addition of

• polypeptides.
• polyacrylamide.
• agar
• gelatin

What type of medium provides the best opportunity for growing and observing the morphology of isolated colonies?

• slants
• broth
• agar plates

The best time period to observe incubated cultures is between ________ hours.

• 12 and 18
• 4 and 12
• 0 and 4
• 24 and 48

Gram-negative organisms might incorrectly stain purple.

• You forgot to apply safranin
• You forgot the decolorization step.
• You forgot the Gram's iodine.
• You applied the decolorizer for too long.
• You forgot the crystal violet step.
• You did not heat fix the smear correctly.

Gram-negative organisms might not be visible.

• You forgot to apply safranin
• You forgot the decolorization step.
• You forgot the Gram's iodine.
• You applied the decolorizer for too long.
• You forgot the crystal violet step.
• You did not heat fix the smear correctly.

Gram-positive organisms might incorrectly stain pink.

• You forgot to apply safranin
• You forgot the decolorization step.
• You forgot the Gram's iodine.
• You applied the decolorizer for too long.
• You forgot the crystal violet step.
• You did not heat fix the smear correctly.

You may not be able to view any organisms on the slide.

• You forgot to apply safranin
• You forgot the decolorization step.
• You forgot the Gram's iodine.
• You applied the decolorizer for too long.
• You forgot the crystal violet step.
• You did not heat fix the smear correctly.

Reagent

• None (Heat-fixed cells)
• Crystal Violet (30 seconds)
• Gram's Iodine (1 minute)
• Ethyl Alcohol (5-15 seconds)
• Safranin (1 minute)

Gram-positive

• purple
• pink/red

Gram-negative

• purple
• pink/red

Please order the following choices to reflect the appropriate sequence of materials used in the Gram staining procedure.

• Gram's Iodine
• Safranin
• Crystal Violet
• Alcohol

Match the following reagents with their role in the Gram stain procedure.

1. Safranin
2. Gram's iodine
3. Crystal violet
4. Alcohol/acetone

• mordant
• primary stain
• counterstain
• decolorizer

Before heat fixation, a wet smear of bacterial cells on a slide must first be

• rinsed briefly with water
• air-dried
• stained with a basic dye
• blotted dry

Select the statements that represent goals incorrect 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.

Order these statements to indicate correct aseptic procedure for removing organisms from a culture for application to a slide.

• Flame the mouth of the culture tube
• Place organisms onto the slide in the center of the target circle
• Flame the loop red-hot before setting aside
• Remove the cap of the culture tube and flame the mouth of the tube.
• Remove a loopful of organisms from the culture.
• Return the cap to the culture tube.
• Heat inoculating loop and wire to red-hot.

How does smear preparation of cells from a liquid medium differ from preparation of cells from a solid medium?

• Stain is applied to the cells in the culture tube and then they are applied to the slide.
• Heat fixation is used to evaporate the liquid medium.
• A needle is used instead of an inoculating loop.
• Water is applied to the slide before emulsifying cells from a solid medium.

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
• synthetic
• negative
• simple

Gram Stain

Capsule Stain

Simple Stain

Acid-Fast Stain

Gram-positive cells

• Cells which contain a thick layer of peptidoglycan and teichoic acid
• Cells which contain both an inner and outer membrane as well as a thin layer of peptidoglyan
• Cells which contain a thick layer of mycolic acid or cord factor

Gram-negative cells

• Cells which contain a thick layer of peptidoglycan and teichoic acid
• Cells which contain both an inner and outer membrane as well as a thin layer of peptidoglyan
• Cells which contain a thick layer of mycolic acid or cord factor

Acid-fast cells

• Cells which contain a thick layer of peptidoglycan and teichoic acid
• Cells which contain both an inner and outer membrane as well as a thin layer of peptidoglyan
• Cells which contain a thick layer of mycolic acid or cord factor

Spore Stain

Gram Stain

Acid-Fast Stain

The capsule can be considered a virulence factor and microorganisms containing one are often pathogenic.

• True
• False

A _______ stain is one that colors the background surrounding the cell, leaving the cell itself unstained.

• complex
• differential
• negative
• positive

Vegetative Cells

Endospores

Which of the following is a layer found outside of the bacterial cell wall and membrane consisting of repeating sugar units and/or proteins that is resistant to staining.

• glycocalyx and capsule
• capsule
• slime layer
• glycocalyx
• glycocalyx, capsule, and slime

Before heat fixation, a wet smear of bacterial cells on a slide must first be

• air-dried
• stained with a basic dye
• rinsed briefly with water
• blotted dry

Order the reagents used in the acid-fast staining procedure.

• Methylene blue
• Acid-alcohol
• Carbolfuchsin

You observe this slide under the microscope. It was prepared with a negative stain used to visualize capsules.

• This bacterium is encapsulated
• This bacterium is not encapsulated
• The bacterial cells are dark purple
• The capsules are dark purple
• The background of the slide is white, indicating that the slide is densely covered with cells
• The capsules are white spaces around dark cells in this field.

How does smear preparation of cells from a liquid medium differ from preparation of cells from a solid medium?

• A needle is used instead of an inoculating loop
• Water is applied to the slide before emulsifying cells from a solid medium
• Heat fixation is used to evaporate the liquid medium
• Stain is applied to the cells in the culture tube and then they are applied to the slide

A ________ is a mound of cells on a solid medium that represents the progeny from one original bacterial cell.

• streak
• quadrant
• culture
• colony

The ________ is an appropriate tool to use for inoculating microorganisms into the butt of an agar slant.

• spreader
• inoculating loop
• pipette
• inoculating needle

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 appear turbid

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

When completing a quadrant streak, when do you flame the loop? (Check all that apply.)

• It requires fewer materials
• It requires less skill
• It is a very quick process
• It does not require the use of heat

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

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
• agar slant
• broth

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

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

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 slants shows only one color of growth
• The slant appear turbid

What advantage does the pour plate method have over the quadrant streak plate method?

• It requires fewer materials
• It requires less skill
• It only requires an inoculating tool and one plate
• It provides isolated colonies

When preparing pure cultures, dilution is necessary for

• providing a hypotonic environment to enhance bacterial growth.
• ensuring that the bacteria receive adequate nutrition during incubation.
• preparing the melted agar for pour plating.
• reducing the number of inoculated organisms so that isolated colonies can develop.

The type of culture most frequently used in the laboratory which contains only a single species of microbe.

• Pure culture
• Subculture
• Mixed culture
• Contaminated culture

A second-level culture where an isolated colony from one culture is taken and transferred into a new medium.

• Pure culture
• Subculture
• Mixed culture
• Contaminated culture

A culture which contains two or more species which can be easily differentiated.

• Pure culture
• Subculture
• Mixed culture
• Contaminated culture

A culture which contains one or more unwanted and often unidentified microbes.

• Pure culture
• Subculture
• Mixed culture
• Contaminated culture

A ________ is a mound of cells on a solid medium that represents the progeny from one original bacterial cell.

• streak
• culture
• colony
• quadrant

Place the following steps in order to demonstrate your understanding of the pour plate method.

• Remove loopful of organisms from culture using aseptic technique.
• Incubate for 24–48 hours.
• Liquefy nutrient agar tubes and maintain at 50 degrees Celsius.
• Transfer one loopful from one agar tube into another agar tube, and repeat this again with a third agar tube.
• Add loopful of organisms to an agar tube.
• Pour liquefied agar tubes into empty plates.

When performing a Standard Plate Count (SPC), plates that contain ________ colonies are selected for counting with a colony counter.

• 30-300 colonies
• 50-100 colonies
• 100-500 colonies
• 10-100 colonies

Which gas is produced by cell respiration?

• hydrogen
• oxygen
• carbon dioxide
• nitrogen

Starch is a(n)

• oligosaccharide
• monosaccharide
• disaccharide
• polysaccharide

The main products of yeast fermentation are (Check all that apply)

• alcohol
• FADH
• CO
• CO2
• latic acid
• NAD+
• NADH
• pyruvate

Polysaccharides are polymers composed of

• fatty acids
• nucleotides
• amino acids
• nucleic acids
• sugars

All of the following are the end products of glycolysis except

• energy
• pyruvate
• ATP
• NAD+
• NADH

When testing for starch within the potato and onion, the test tube containing potato turned purple while the test tube containing onion turned orange. What can you conclude about the amount of starch in these two vegetables?

• The potato contained a higher concentration of starch than the onion.
• The potato contained starch, but the onion did not.
• The potato contained no starch, but the onion did.
• The potato contained lower concentration of starch than the onion did.
• Neither the potato nor the onion contained starch.

Which of the following does NOT occur during yeast fermentation?

• NADH is oxidized to NAD+
• Lactate is produced
• Glucose is oxidized to make Pyruvate
• Pyruvate is oxidized forming CO2 and ethanol
• NAD+ is reduced to NADH

Select all of the following that are products of lactic acid fermentation.

• glucose
• water
• oxygen
• lactic acid
• carbon dioxide
• ATP

Yeast cells under anaerobic conditions

• die
• switch to oxidative respiration
• push the glycolytic pathway backward
• produce oxygen
• produce ethyl alcohol (ethanol)

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

Starch is classified as a

• nucleic acid
• protein
• lipid
• carbohydrate

Which of the following is absolutely required for the production of ATP?

• Pi
• production of water
• glucose
• ADP and Pi
• ADP only

The positive control for the Iodine test was the

• olive oil
• glucose solution
• starch solution
• distilled water
• albumin solution

What must occur before sucrose is used in cellular respiration?

• Glucose and fructose must be bonded together
• Oxygen levels must be low from increased metabolism
• Sucrase enzyme breaks it down to glucose and fructose
• Sucrose must first be converted into a disaccharide

What is produced when beer is made?

• oxygen and ethanol
• lactate and ethanol
• ethyl alcohol and water
• water, hydrogen gas, and ethanol
• CO2 and ethanol

Under what environmental conditions do yeast carry out fermentation?

• All of the choices are correct
• absence of oxygen
• high osmotic pressure
• high temperature
• low pH

What anaerobic pathway in cellular respiration generates ATP from the breakdown of glucose?

• the light reactions
• Calvin cycle
• electron transport chain
• citric acid cycle
• glycolysis

Which of the following is the purpose of cellular respiration?

• splitting water
• production of glucose
• production of ATP
• production of water

What would you predict would happen to the fermentation rate if you used yeast suspension that had not been swirled/mixed each time before it was dispensed into test tubes?

• The reaction rate would be uniform, since the yeast would be undisturbed
• The reaction rate would be very low
• The reaction rate would be unaffected
• The reaction rate would be very high at first, but would steadily decrease over time
• The reaction rate would be very high

Bacteria that are able to hydrolyze urea will change the color of the urease test medium from yellow to

• red
• green
• blue
• pink

The phenol red indicator used in the urease test turns pink when the test medium

• is basic
• has a pH less than 7
• liquifies
• is acidic

An amino acid consists of

• a carboxyl group
• an amino group
• a ribose group
• a side group
• a hydroxyl group

The color change in a positive citrate test is due to a/an _____________ in pH.

• increase
• decrease

What is the color change that indicates a positive citrate test?

• Green to blue
• Yellow to pink
• Blue to green
• Pink to yellow

Amino acids are joined by

• ionic bonds
• glycosidic bonds
• peptide bonds
• ester bonds

What is the product of urea hydrolysis?

• ammonia and carbon dioxide
• ammonia
• carbon dioxide
• organic acids

After inoculating and incubating a gelatin deep with an unknown bacterium, you observe that the gelatin deep has liquified. What is the next step in the experiment?

• Test the components of the liquid gelatin
• Conclude that the unknown bacterium is able to hydrolyze gelatin
• Place the gelatin deep on ice
• Incubate the gelatin deep for an additional 48 hours

Proteins are made up of _______________ subunits.

Helicobacter pylori gastric infections can be diagnosed by a breath test. Patients are instructed to exhale into a balloon-like bag 30 minutes after drinking a urea solution. What gas is being measured when a patient exhales into the bag?

• nitrous oxide
• oxygen
• carbon dioxide
• nitrogen

Which of the following can occur during protein catabolism?

• desulfhydrase reaction
• decarboxylation
• deamination
• All of the above

What is the smallest unit of a protein?

• an amino acid
• a polypeptide
• a monosaccharide
• a nucleic acid

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?

• Cysteine has been decarboxylated, and its COOH removed
• Cysteine has been converted into smaller amino acids
• The bacteria has released cysteine from the polypeptide chains
• The bacteria has released Hydrogen Sulfide from cysteine

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 is produced by anaerobic organisms
• Because the cells are motile and have travelled to the bottom of the stab
• Because there is more bacterial growth at the bottom of the stab
• Because Hydrogen Sulfide gas is released into the air closer to the media surface and therefore wouldn't produce the ferrous sulfide black precipitate.

What would the Litmus Milk test look like if the inoculated bacteria was able to ferment lactose?

• The media would clear
• The media would change to purple
• There would be white precipitates in the media
• The media would change to pink

What change in litmus milk would occur if amino acids were catabolized?

• Coagulation of media would occur
• Media would turn pink
• Media would turn purple
• Media would turn clear

What change in litmus milk would occur if there were very high levels of acid produced following lactose fermentation?

• Coagulation of media would occur
• Media would turn purple
• Media would turn clear
• Media would turn pink

Which of the following is NOT found in Litmus Milk media?

• lactose sugar
• Bromthymol blue
• milk casein protein
• litmus

Which of the following is NOT present in Triple Sugar Iron Agar media?

• All of the above are included
• phenol red indicator
• 0.1% glucose
• 1% lactose
• 1% sucrose

Which one of the following can be determined through the results of a Triple Sugar Iron Agar Test?

• All of the above
• Fermentation of glucose
• Fermentation of lactose and sucrose
• Production of hydrogen sulfide

What is the final step in aerobic cellular respiration?

• Lactic Acid Fermentation
• Electron Transport Chain
• Kreb's Cycle
• Glycolysis

What is the final step in aerobic cellular respiration?

• Lactic Acid Fermentation
• Electron Transport Chain
• Kreb's Cycle
• Glycolysis

Coagulase Test: Place the following steps in the correct order.

• look for clotting
• Using sterile loop, obtain bacteria colony and mix with coagulase plasma
• Place loopful of coagulase plasma on clean slide using sterile loop.

If no color change has occurred in the nitrate reductase test after adding Nitrate I and Nitrate II to your culture, what do you add to your culture to determine if you have a positive or negative result?

• Potassium
• Zinc
• Carbon
• Magnesium

This test is used to differentiate between Staphylococcus (catalase-positive) and Streptococcus (catalase-negative), as both are Gram-positive cocci.

• Catalase Test
• Coagulase Test
• Nitrate Reductase Test
• Gram Staining Test
• Oxidase Test

Coagulase Test: A positive test is indicated by ____?

Which of the following is not found in a Mannitol Salt Agar Plate?

• peptone
• salt
• mannitol
• alcohol

This media differentiates between lactose fermentors.

• none of these options are correct
• Mannitol Salt Agar
• Eosin Methylene Blue
• Blood Agar

Which of the following is not a correct description of selective media?

• contains one or more specific compounds that can prevent the growth of certain bacterial species
• inhibitors in the media may adversely effect DNA synthesis, gene expression, enzymatic activity or membrane permeability all of which can destroy or inhibit the growth of certain bacterial species
• allows the growth of some bacterial species while inhibiting the growth of other bacterial species
• contains one or more specific compounds that can distinguish between bacterial species
• can be used to identify bacteriacan

A clinical sample may contain many different types of bacteria that do not have to be identified. You wouldn't want to waste time culturing all bacteria if, for example, you suspect a gram-negative bacteria is what is causing the infection. What plate can you use to select for only gram-negative bacteria?

• Eosin Methylene Blue
• Nutrient Agar
• Mannitol Salt Agar
• Blood Agar

This test is used to identify bacteria who have similar Electron Transport Chains to those found in Eukaryotes, which contain the Enzyme Complex IV (Cytochrome C Oxidase).

• Catalase Test
• Oxidase Test
• Cytochrome C test
• Coagulase Test
• Nitrate Reductase Test

Which of the following is true?

• The nitrate reductase test is important in the identification of both gram-positive and gram-negative species.
• In the nitrate reductase test, there are two ways to read a positive result but only one way to be negative.
• The oxidase test is basically a test to see if an organism is an aerobe.
• In the electron transport chain, O₂ is typically the final electron acceptor.

Which of the following is false?

• Staphylococcus aureus would yield a negative result in a coagulase test.
• Staphylococcus epidermis would yield a positive result in a coagulase test.
• Staphylococcus aureus ferments mannitol, causing the phenol red to turn yellow.
• Staphylococcus epidermis tolerates high salt concentration and grows on Mannitol Salt Agar (MSA).
• Staphylococcus epidermis is gram-positive cocci and coagulase-positive.
• Staphylococcus aureus is gram-negative cocci and coagulase-negative.

Take a look at the results of a Nitrate Reductase test below.

Which of the following (if any) is considered a negative result?

• Streptococcus pneumoniae
• None of the bacteria tested yielded a negative result.
• Escherichia coli
• Pseudomonas aeruginosa
• Staphylococcus epidermidis

Which of the following is produced by the human immune system and is a common byproduct of metabolic reactions that take place in the presence of water and oxygen?

• Hydrogen Peroxide
• Nitrite
• Dihydrogen Monoxide
• Oxygen
• Nitrate

Which of the following is not considered a positive result?

• If no color change occurs upon addition of zinc then this means that the NO^3- was converted to NO^2- and then was converted to some other undetectable form of nitrogen.
• If no red color forms upon addition of nitrate I and II, this indicates that NO^3- was converted to NO^2- and then immediately reduced to some other, undetectable form of nitrogen.
• If nitrite is present in the media, then it will react with nitrate I and nitrate II to form a red compound.
• Zinc will convert any remaining NO^3- to NO^2- thus allowing nitrate I and nitrate II to react with the NO^2- and form the red pigment.

Match the following descriptions to their respective plates.

1. Can be used as a positive control for selective and differential media
2. selects for gram-positive cells
3. Clear ring around colony distinguishes certain bacteria
4. medium fermenters result in purple colonies

• Eosin Methylene Blue Agar
• Blood Agar
• Mannitol Salt Agar
• Nutrient Agar

Which of the following is not found in an Eosin Methylene Blue (EMB) Plate?

• polypeptides
• eosin
• methylene blue
• lactose
• galactose