Microbiology - Lab Final
The most important approach to identifying unknowns is the phenotypic method.
False
The presence or absence of oxygen has no effect on the growth of microbes. True false question.
False
The sources of all antimicrobial drugs are fungi and other microorganisms.
False
The zone of inhibition is measured by adding 5 mm to the radius of the clear zone around the antibiotic disc.
False
UV radiation has very limited uses in medical and industrial settings.
False
Ultraviolet radiation exists almost exactly in the middle of the electromagnetic radiation wavelength spectrum.
False
Which of the following is a toxic by-product formed in the presence of oxygen?
Superoxide ion Peroxide Hydroxyl radical
Which of the following can be disinfected using UV radiation?
Surfaces Liquids, such as water and cider Air
Which of the following are examples of physical methods of microbial control?
Temperature Irradiation
The pink color in a tube of fluid thioglycollate medium (FTM) indicates the _____ of oxygen.
presence
What does the master mix solution contain?
Heat stable polymerase Free deoxynucleotides
Hypertonic solution
There will be a net movement of water out of the cells.
Rank these organisms from the most difficult to destroy or control to the easiest to control.
1. Bacterial endospores 2. Pseudomonas aeruginosa 3. Streptococcus species
Place the steps of one PCR cycle into the correct order.
1. Denaturation 2. Priming 3. Extension
Rank these from the easiest to remove or destroy to the most difficult to remove or destroy.
1. Enveloped viruses (such as the Influenza virus) 2. Mycobacterium tuberculosis 3. Prions
Rank the following, from the highest growth temperature range (at the top) to the lowest growth temperature range (at the bottom).
1. Extreme thermophile 2. Thermophile 3. Mesophile 4. Psychrotroph 5. Psychrophile
Place the steps of the Kirby-Bauer method of antibiotic susceptibility testing in the order in which they are performed.
1. Using a cotton-tipped swab, inoculate a plate of Mueller-Hinton agar with the bacteria to be tested, and covering all surfaces of the plate in order to develop a lawn of growth. 2. Place antibiotic disks onto the surface of the inoculated plate, and tap slightly so that they adhere to the surface. 3. Incubate the inverted plate at 37 ºC overnight. 4. Observe the plate and measure the diameters of the zones of inhibition. 5. Compare diameters to chart of interpretive criteria.
This image shows an unknown bacterium after 24-hour incubation on a blood agar plate. What hemolytic result is seen here?
Beta hemolysis
Which of the following reflects the wavelength range of UV radiation?
100-380 nm
The enterotube system contains tests, while the API 20E testing strip contains tests.
12;20
Looking at this set of images from another experiment, what is the minimum length of UV light exposure that could be used to disinfect an area contaminated with bacteria?
2.5 minutes
As an epidemiologist, you are collecting statistics on the number of patients that are part of the current Salmonella outbreak. What percentage of these tested patients are positive for the outbreak strain?
20%
What is the correct measurement of this zone of inhibition?
21 millimeters
Using the DNA ladder provided, estimate the size of the largest DNA fragment in lane 4.
2322 base pairs
To promote the development of red-pigmented colonies by Serratia marcescens, cultures should be incubated at
25 degrees C.
Which of the following would be used to provide the optimum growth temperature for microorganisms that typically grow in humans?
37 ℃ incubator
Which of these would be least likely to be resistant to antimicrobial drugs?
A fungal infection
Which statement best describes the growth patterns of microorganisms based on their temperature preferences?
A microorganism will grow across the range of temperatures tolerated by its enzymes.
Hypotonic solution
A net movement of water into the cells will occur.
Disinfectants are often used to clean skin wounds as they are highly effective chemical agents against most bacterial species.
False
Which of the following is accomplished by use of PCR?
A specific sequence of DNA can be amplified a billion fold.
Which of the following are examples of physiological (biochemical) characteristics that could be used in the bacterial identification process?
Ability to break down lipids Presence of specific enzyme Ability to ferment glucose
Given the optical data above for each pH, how would the test organism be categorized?
Acidophile
When are chemical-saturated disks placed on the plate during a test of disinfectants?
After streaking out the test organisms, but before incubation.
This image shows an unknown bacterium after 24-hour incubation on a blood agar plate. What hemolytic result is seen here?
Alpha hemolysis
How is it visually determined that the environment inside an anaerobic jar contains no oxygen?
An indicator strip is placed into the chamber before it is sealed which will change color in the presence of oxygen.
Match the microbial control term with its description. A chemical is used to remove or destroy vegetative pathogens on skin or tissue: A process that destroys or removes all forms of microbial life, including endospores: A chemical is used to remove or destroy vegetative pathogens on inanimate objects:
Antiseptic Sterilization Disinfectant
An unknown bacterium was streaked on the top half of a blood agar plate and a bacitracin disc was placed on it. A vertical streak with the unknown bacterium was made, along with an intersecting horizontal streak with S. aureus. After 24 hours, your plate looked like this image. What can you determine from this result?
Bacitracin resistant / CAMP negative
An unknown bacterium was streaked on the top half of a blood agar plate and a bacitracin disc was placed on it. A vertical streak with the unknown bacterium was made, along with an intersecting horizontal streak with S. aureus. After 24 hours, your plate looked like this image. What can you determine from this result?
Bacitracin resistant / CAMP positive
What is the internationally recognized reference for bacterial classification and identification?
Bergey's Manual
Facultative anaerobe:
Can conduct aerobic or anaerobic metabolism; can process toxic oxygen by-products.
Which enzymes are necessary for cells to survive in an oxygen environment?
Catalase Peroxidase Superoxide dismutase
What biochemical test is most useful in differentiating Staphylococcus species from Streptococcus species?
Catalase test
Which of the following is an example of a morphological characteristic that could be used in the bacterial identification process?
Cell shape
Bergey's Manual of Determinative Bacteriology first categorizes bacteria based upon which of the following characteristics?
Cell shape Gram stain reaction
An organism produces a urease enzyme. Which of the following describes the color change expected in the test medium for this enzyme?
Changes from yellow to bright pink
Which biochemical test makes use of rabbit plasma as a reagent?
Coagulase test
Which biochemical test requires rabbit plasma as a reagent and its results are determined by observation of thickening of the medium?
Coagulase test
What cultural characteristics can be described by color and shape?
Colony morphology
An organism can utilize citrate as its sole carbon source and ammonium salts as its sole nitrogen source. What change would you expect to see in a citrate slant inoculated with this organism?
Color change from green to blue
In which circumstances would we attempt to optimize conditions for microbial growth?
Composting yard waste Culturing a urine specimen to detect a urinary tract infection. Manufacturing yogurt
Which of the following may benefit from the identification of specific microorganisms?
Criminal investigations Treatment of infectious disease Environmental bioremediation programs Water quality analysis Detection of a bioterrorism attack
An isotonic solution prevents water from crossing the cell membrane.
False
What part of a cell is damaged by UV radiation?
DNA
Which of the following are potential applications of PCR?
Detection of DNA during crime scene analysis. Detection of DNA from victims of massive disasters. Detection and identification of infectious agents in patient samples.
Which would be the main reason for trying to identify which antibiotics would be the best to treat a particular patient?
Diagnosis and treatment of infections
Which of the following types of media might be particularly helpful in the isolation of a bacterial species from a mixed bacterial culture?
Differential Selective
Which of the following are chemical means of microbial control?
Disinfectant Ethanol wipe
Obligate anaerobe:
Does not use gaseous oxygen in its energy metabolism; unable to process toxic oxygen by-products.
At the conclusion of a test for disinfectants, there will be a ring of growth around the filter paper discs and the rest of the plate will be clearly demonstrating a zone of inhibition.
False
Bacterial transformation only occurs in the laboratory when creating recombinant bacteria.
False
Because bacteria reproduce asexually they rely on vertical gene transfer to gain genetic diversty.
False
During which step of the PCR cycle is the thermostable DNA polymerase most active?
Extension
Which of the following organisms is most flexible with regard to its oxygen requirements?
Facultative anaerobe
Based on this FTM tube result, how would you classify this organism?
Facultative anaerobe The organism will be using aerobic metabolism.
Organism at #1: Neither organism #1 or #2 would be classified as this type: Organism at #2:
Facultative anaerobe Obligate anaerobe Obligate aerobe
A standard set of biochemical tests is used to identify all types of bacteria, regardless of morphological and cultural characteristics.
False
All microorganisms use oxygen in their metabolism.
False
This image shows an unknown bacterium after 24-hour incubation on a blood agar plate. What hemolytic result is seen here?
Gamma hemolysis
What method is used to separate out restriction fragments after cutting with restriction enzymes?
Gel electrophoresis
What three main approaches can be used by microbiologists to identify microorganisms?
Genetic Immunologic Phenotypic
Which methods used in bacterial identification usually work best in organisms that cannot be cultured?
Genotypic methods
________ identification methods examine the DNA sequence of an organism, whereas ________ identification methods use antibody-antigen reactions to identify microorganisms.
Genotypic; immunologic
This is how the KIA test looks after 24 hours of incubation. Is the unknown bacterium positive or negative for glucose fermentation, lactose fermentation, and H2SH2S production?
Glucose fermentation= Positive Lactose fermentation= Negative H2SH2S= Negative
This is how the KIA test looks after 24 hours of incubation. Is the unknown bacterium positive or negative for glucose fermentation, lactose fermentation, and H2SH2S production?
Glucose fermentation= Positive Lactose fermentation= Negative H2SH2S= Positive
This is how the KIA test looks after 24 hours of incubation. Is the unknown bacterium positive or negative for glucose fermentation, lactose fermentation, and H2SH2S production?
Glucose fermentation= Positive Lactose fermentation= Positive H2SH2S= Positive
Which of the following chemicals are used primarily as disinfectants?
Glutaraldehyde Chlorine bleach
The first choice in this dichotomous key is based on the organism's
Gram reaction.
Now that a pure culture has been isolated for you, what would be a good starting procedure to begin classifying your unknown organism?
Gram staining
This is how the SIM medium looks after 24 hours and the addition of indole reagent. Is the unknown bacterium positive or negative for H2SH2Sproduction, indole production, and motility?
H2SH2S = Negative Indole= Positive Motility= Positive
This is how the SIM medium looks after 24 hours and the addition of indole reagent. Is the unknown bacterium positive or negative for H2SH2S production, indole production, and motility?
H2SH2S = Positive Indole= Negative Motility= Positive
Halobacterium salinarium will only grow at high salt concentrations, generally 15% to 30% NaCl. Which term below describes this environmental preference?
Halophilic
Which of the following microbial characteristics can be determined by growing the bacteria on blood agar?
Hemolysis
Which organisms grow at the highest temperature?
Hyperthermophiles
Which methods used to identify a microorganism causing an infection rely on the response of the host, rather than observation of the microorganism's properties?
Immunologic methods
Which of the following are advantages of using multitest media or systems?
Improved efficiency Reduction in media usage Reduction in time required for identification
Which of the following are used to describe the range of temperatures over which a microbe will grow?
Optimum growth temperature Minimum growth temperature Maximum growth temperature
Your task is to determine the oxygen requirement classification for several organisms. Choose an appropriate strategy for this experiment.
Inoculate two plates with the three organisms in separate areas. Place one plate on incubator shelf and one in the anaerobe jar for 24 hours and observe.
What is the purpose of the LB agar plate?
It is a non selective medium for bacterial growth
What is the purpose of the LB/amp agar plate?
It is a selective medium containing an antibiotic to inhibit the growth of non-resistant cells.
Which biochemical test would be most useful for differentiating Streptococcus pneumonia and viridans streptococci?
Optochin susceptibility
Which of the following terms refers to microorganisms capable of growing in jams, corn syrup, and maple syrup?
Osmophilic
Which of the following methods could be used to isolate bacteria from a mixed culture?
Loop dilution pour plating Streak plating Serial dilution followed by spread plating
Where would you expect an obligate anaerobe to grow in a tube of fluid thioglycollate medium?
Lower part of the tube
Which of the following correctly describes the measurement of the zone of inhibition?
Measure the complete diameter of the zone, from the edge of the zone on one side of the disk, across the disk to the edge of the zone on the other side, in mm.
Which of the following may occur at temperatures below a microorganism's minimum growth temperature?
Membrane transport may be disrupted Decreased fluidity of the plasma membrane Slowing of metabolic activity
You inoculated the broths seen here with Staphylococcus epidermidis and incubated at the labeled temperatures. How would you classify this organism based on its growth at different temperatures?
Mesophile
Which of the following are direct targets of antimicrobial control methods?
Metabolic enzymes Cell membrane Nucleic acid synthesis Cell wall Protein synthesis
What is the preferred medium for use with the Kirby-Bauer susceptibility test?
Mueller-Hinton agar
Which type of antibiotic is most likely to target the pathogen without causing a decrease in the normal microbiota?
Narrow-spectrum
After adding reagents A and B (from a nitrate test kit), you see this result in image 1- a yellow color. After adding zinc, the color changes from yellow to red, seen in image 2. Is the unknown bacterium positive or negative for nitrate reductase?
Negative
Is this bacterial isolate positive or negative for catalase activity?
Negative
Is this bacterial strain positive or negative for mannitol fermentation?
Negative
This is how the Durham tube looks after 24 h. Is this bacterium positive or negative for glucose fermentation?
Negative
This is how the MacConkey agar plate looks after 24 hours of incubation. Are these bacteria positive or negative for lactose fermentation?
Negative
Twelve hours after adding a sample of bacteria to rabbit serum, your tube looks like this. Are the unknown bacteria positive or negative for coagulase activity?
Negative
You conducted a citrate test. Is this result positive or negative?
Negative
You conducted an oxidase test to detect the production of an oxidase enzyme. Is the result positive or negative?
Negative
You evaluate a bile esculin agar slant 24 hours after you inoculated it with your unknown bacterium. Is the bacterium positive or negative for esculin hydrolysis?
Negative
Which of the following is a product of nitrate reduction that is directly detected via the nitrate reduction test?
Nitrite
According to this flowchart, what test is most useful for distinguishing between Escherichia coli and Vibrio cholerae?
Oxidase test
Which of the following is an example of a culturing requirement that could be used in the bacterial identification process?
Oxygen preferences
Which term describes an organism that requires the presence of oxygen for growth?
Obligate aerobe
Which of the organisms would not have grown if placed in the anaerobic jar?
Obligate aerobes
Which organism(s) should be able to grow in the anaerobe jar?
Obligate anaerobe Facultative anaerobe
Where would you expect to see growth for an obligate aerobe?
On a plate placed on the incubator shelf but not within the anaerobic jar.
Which methods used in bacterial identification usually require culturing of the unknown bacteria?
Phenotypic
Is this bacterial isolate positive or negative for catalase activity?
Positive
Is this bacterial strain positive or negative for mannitol fermentation?
Positive
This is how the Durham tube looks after 24 h. Is this bacterium positive or negative for glucose fermentation?
Positive
This is how the MacConkey agar plate looks after 24 hours of incubation. Are these bacteria positive or negative for lactose fermentation?
Positive
Twelve hours after adding a sample of bacteria to rabbit plasma, your tube looks like this. Are the unknown bacteria positive or negative for coagulase activity?
Positive
You conducted a citrate test. Is this result positive or negative?
Positive
You conducted a methyl red test. Is the result positive or negative?
Positive
You conducted a urease test. Is this result positive or negative for urease activity?
Positive
You conducted an oxidase test to detect the production of the oxidase enzyme. Is the result positive or negative?
Positive
You evaluate a bile esculin agar slant 24 hours after you inoculated it with your unknown bacterium. Is the bacterium positive or negative for esculin hydrolysis?
Positive
Based on the results of a disk diffusion antimicrobial susceptibility test, an organism may be described as sensitive, intermediate, or resistant to the drug. Match the term with its description. The growth of the microorganism is significantly inhibited by the drug: The microorganism is not affected by the drug and can grow in its presence: The drug demonstrates moderate inhibition of the microorganism:
Sensitive Resistant Intermediate
What is the final end product of the Central Dogma of Biology?
Protein
Which of the following are most likely to be affected by pH changes?
Proteins
Which two types of bacteria listed below are moderately resistant to microbial control methods?
Pseudomonas aeruginosa Mycobacterium tuberculosis
The data table shown here indicates the absorbance readings for broth inoculations incubated at different temperatures (Celsius). Based on these readings, how would you classify this organism according to its temperature preferences?
Psychrophile
Which classifications of organisms can be a concern for growth in refrigerated foods?
Psychrotrophs Psychrophiles
Which of these laboratory items are usually used to inhibit the growth of most types of microorganisms by altering their environment?
Refrigerator Salt plates
Which of the following is a characteristic of members of the resident microbiota?
Resident microbiota can compete with and limit the growth of harmful bacteria.
You streak your unknown bacterium onto a blood agar plate and place a novobiocin disc onto the surface of the plate. After 24 hours, your plate looks like this. Is the unknown bacterium sensitive or resistant to novobiocin?
Resistant
You streak your unknown bacterium onto a blood agar plate and place an optochin disc on the surface of the plate. After 24 hours, your plate looks like this. Is the unknown bacterium sensitive or resistant to optochin?
Resistant
Which of the following media tests can provide information on more than one biochemical characteristic?
SIM tubes Kligler's iron agar (KIA)
You streak your unknown bacterium onto a blood agar plate and place an optochin disc on the surface of the plate. After 24 hours, your plate looks like this. Is the unknown bacterium sensitive or resistant to optochin?
Sensitive
Which statements correctly explain why DNA from two individuals will produce different fragments after cutting by restriction enzymes?
Single-base differences in their DNA sequence can cause changes in the location of restriction enzyme cutting sites. The location of restriction enzyme cutting sites determines the size of the DNA fragments when cut with that enzyme.
Which of the following are risks associated with UV exposure?
Skin cancer Eye damage
Which of the following cannot be effectively disinfected using UV radiation?
Skin wounds
What is the importance of labeling each plate?
So the placement of each of the 3 bacterial samples will be marked and visible. To know the salt content of each plate.
Where do antimicrobial drugs come from?
Some come from microbes, others are synthetically produced.
What do common biochemical tests look for?
Specific enzymatic reactions Breakdown of nutrients Fermentation products
Human skin provides an environment with NaCl levels slightly above that of most bacterial cells. Which organism would most likely be found on the skin?
Staphylococcus aureus; a halotolerant organism
Place the steps of the experiment in the correct order.
Step 1 : Use a swab to create a lawn of the bacterial specimen to be tested onto the surface of a Mueller-Hinton agar plate. Step 2 : Place antibiotic discs onto the surface of the inoculated plate. Step 3 : After incubation measure the zones of inhibition for each antibiotic. Step 4 : Compare zones to interpretive table to determine susceptibility and resistance to each antibiotic.
Which of the following processes removes or destroys endospores?
Sterilization
Which of the following is the quickest way to isolate bacteria from a mixed culture?
Streak plating
Which of the following are included in the study of medical microbiology?
Study of immunology, the body's response to infectious agents. Study of approaches used in the prevention of infectious disease. Development and use of methods for detection of infectious disease. Study of microbes that impact human health.
A bacterial strain has been isolated from a patient's urine specimen and a Kirby-Bauer susceptibility test has been done on the bacterial strain. There is no zone of inhibition around antibiotic X. Which statement correctly describes this situation?
The bacteria is resistant to antibiotic X.
Which of the following explain the difference in gel results for the outbreak strain in patient D?
The bacterial DNA sequence is different from the DNA sequence of the outbreak strain. The outbreak strain had more restriction digest sites than the bacterial DNA in patient D.
A hypertonic solution is prepared by the addition of sucrose. Which of the following will happen to bacteria placed in this solution?
The bacterial cells will undergo plasmolysis.
Following PCR, the products were loaded into a gel and electrophoresis was performed. Following visualization of the gel, no band of DNA was observed. What explains this result?
The desired sequence was not successfully amplified.
How should the zone of inhibition be measured?
The diameter of the zone(in mm) is measured, from one edge of the zone, across the disk, to the other edge of the zone.
How do antimicrobial drugs affect target microorganisms?
The drugs may stop the growth of the microorganisms without killing them. The drugs may kill the microorganisms.
The best approach to the control of microbial growth often hinges on whether body tissues or inanimate objects are involved.
True
The optimum temperature of an organism is closer to its maximum growth temperature than its minimum growth temperature.
True
What causes the color change in a positive urease test?
The production of ammonia from urea
What are the possible outcomes of selecting an antibiotic that is ineffective to treat a particular infection?
The targeted pathogen will continue to grow and cause disease. The infection may worsen. The normal microbiota may be destroyed enabling the targeted pathogen to grow even better.
Which of the following steps that are performed when setting up a test of the effectiveness of chemical agents using the filter paper diffusion method is completed first?
The test microorganism is spread over the surface of an agar plate.
Which portion of an FTM tube would show indications of the presence of oxygen?
The top part of the tube
Isotonic solution
There will be NO net movement of water either into or out of the cells.
Which type of organism would grow well at 55°C?
Thermophile
You inoculate a plate with two different organisms and incubate in an anaerobic jar for 24 hours. This is the result you see after incubation. Which of the following are possible conclusions regarding these organisms?
They cannot be obligate aerobes. They can grow in the absence of oxygen. They may be obligate anaerobes. They may be facultative anaerobes, but that cannot be determined from these results alone.
Which of the following body sites normally have large numbers of resident microbiota?
Throat Skin Nose Vagina Large intestine
Which would be the main reason for identifying which organism is causing infections from contaminated peanut butter?
Tracking of infectious diseases in populations
A drug that reduces the normal microbiota but doesn't effectively target the causative agent of infection may actually make the infection worsen.
True
Controlling microbial growth is important for having safe food and drinking water and for preventing the spread of infectious diseases.
True
Multiple bacterial species can have similar staining reactions and microscopic morphology.
True
Some microorganisms are adapted to living at either very hot temperatures, very cold temperatures, or very low pH.
True
Microaerophile:
Unable to grow in the presence of atmospheric levels of gaseous oxygen, but needs a small amount of oxygen for its metabolism.
Obligate aerobe:
Uses oxygen in its energy metabolism; can process toxic oxygen by-products.
How do you determine the species of an unknown bacterium?
You use standard tests and pre-existing knowledge to classify the bacterium.
In an anaerobe jar, oxygen is
absent.
A(an) jar could be used to provide an oxygen-free atmosphere for bacteria that thrive in the absence of oxygen and are inhibited by its presence.
anaerobe
Chlorhexidine, chloroxylenol, or iodine compounds are often found in antimicrobial soaps used as surgical scrubs. These are examples of _______.
antiseptics
The terms aerobic, anaerobic, and microaerophilic are used to categorize microorganisms based on their _____ requirements.
atmospheric oxygen
If comparing growth of a microbe in broth tubes incubated at different temperatures, the tube incubated at the organism's optimum temperature would
be the most turbid (cloudy).
The complete clearing or hemolysis that a bacterial isolate may produce on blood agar is called hemolysis, while partial hemolysis which produces a greenish discoloration is referred to as hemolysis.
beta;alpha
Bile esculin medium is made selective by the incorporation of , and differential by the incorporation of and ferric citrate.
bile;salts
A specific example of a medium that can be used to isolate organisms from the human body because it is enriched with compounds that support the growth of fastidious organisms is agar.
blood
A particular microbial control agent weakens and destroys peptidoglycan. This would specifically damage the _____.
cell wall
A particular microorganism can be distinguished from several closely related microorganisms by the determination of its preferred growth temperature. This is an example of a _____ characteristic that can be used for identification.
cultural
Temperatures above the maximum growth temperature for a microorganism are likely to result in
denaturation of enzymes.
A key is a flowchart that can be used to identify an organism by making a series of choices until you arrive at one possibility.
dichotomous or identification
Atmospheric gases, nutrients, pH, energy sources, and radiation are all examples of _____ factors that affect microbial growth.
environmental
The slowed growth or lack of growth of an organism at temperatures or pH outside of its ideal range is most likely due to changes in its
enzymes
A tube of fluid thioglycollate medium is inoculated with a bacterial isolate. After incubation, the bacteria appear to be growing throughout the tube. This bacterial isolate is most likely a(n)
facultative anaerobe.
indicate the items needed for PCR
free deoxynucleotides thermostable DNA polymerase primers template DNA with target sequence
Human genes can be introduced into bacterial cells via transformation, after which the bacterial cells express the human gene, producing a human protein such as insulin or growth hormone. The bacterial cell is described as
genetically-modified. a recombinant cell.
Genetic diversity arises in bacteria by means of _____ gene transfer.
horizontal
Distilled water would be _____ to bacterial cells.
hypotonic
The ninth edition of Bergey's Manual of Determinative Bacteriology was designed solely for
identifying bacteria that have already been cultured and phenotypically examined.
The area around an antibiotic disk where microorganisms are NOT growing is referred to as the zone of .
inhibition
The clear area where no bacteria are growing around the chemical disk is called a zone of
inhibition
Microorganisms growing on mucous membranes such as the oral mucosa or vaginal mucosa are most likely in a(an) _____ environment.
isotonic
Identification of a bacterium cannot be made on microscopic morphology alone because
many microorganisms have a similar microscopic morphology.
The field of study in which medicine and microbiology intersect is known as
medical microbiology
Microorganisms whose optimal growth temperature is 37 ℃ (normal human body temperature) are classified as
mesophiles.
Larger fragments migrate _____ through the agarose gel, compared to smaller fragments.
more slowly
The Gram stain is an example of a test that can be used to determine the _____ characteristics of a bacterium. Multiple choice question.
morphological
An antimicrobial, such as isoniazid, that is only effective against mycobacterial species would be considered to be a _____ drug.
narrow-spectrum
A solution with a pH of 7 is
neutral.
If an organism grows in the anaerobe jar but not under normal atmospheric oxygen levels, it would be classified as a(n)
obligate anaerobe.
The fastest growth rate of a microorganism occurs at its _____ temperature.
optimum
The activated chemical pack envelope that is added to an anaerobe jar effectively removes
oxygen.
Which of the following are environmental factors that affect microbial growth?
pH Nutrients Atmospheric gases Osmotic pressure Temperature
Given the optical data above for each pH, what is the optimal pH for the growth of this organism?
pH 3
Based on the images seen here, what is the pH range for growth of this organism?
pH 5-7
Based on the data table below, what would be the likely optimal pH for this organism?
pH 9
An organism has been shown to produce hydrogen sulfide and indole in its metabolism. These are examples of _____ characteristics that can be helpful in identifying the microorganism.
physiological
If an organism produces stable acids as an end-product of glucose fermentation, the methyl red test will be
positive.
An antibiotic that interferes with the activity of ribosomes would have the most direct effect on ______.
protein synthesis
Which of the following are most likely to be affected by pH changes?
proteins.
Before attempting to identify an unknown bacterial species, the organism must be isolated in a culture.
pure
Bacterial enzymes that are used to cut the DNA of infecting bacteriophages are called enzymes.
restriction
Plasmids used as cloning vectors often include a gene for antibiotic resistance. This makes it easier to isolate bacterial cells that have been successfully transformed with the plasmid by using a medium containing the same antibiotic. Such an antibiotic-containing medium would be described as
selective.
When a large zone of no growth is found around an antibiotic disc being used for identification purposes, this means that the microbe is _____ to the antibiotic.
sensitive
The wavelength of ultraviolet radiation is _____ than the wavelengths of visible light.
shorter
A microorganism is classified as a psychrophile, a mesophile, or a thermophile based on its optimum growth
temperature.
A zone of inhibition around a chemical-saturated disk indicates _______.
the chemical is effective at inhibiting the growth of the test organism
UV radiation causes the formation of
thymine dimers
Genes for human growth hormone and for human insulin have been placed into plasmids and introduced into bacteria by means of
transformation.
The process by which a bacterial cell picks up small pieces of naked DNA from the surrounding environment is referred to as
transformation.
A thymine dimer forms between _______.
two adjacent thymines, on the same DNA strand
