Question 1

Phenotypically identical bacteria

Accepted Answer

A)  are genetically exactly the same. 
B)  may be told apart by DNA sequence analysis. 
C)  have similar protein profiles. 
D)  cannot be told apart by any means. 
E)  are referred to by the strain O157:H7. 
A)  are genetically exactly the same. 
B)  may be told apart by DNA sequence analysis. 
C)  have similar protein profiles. 
D)  cannot be told apart by any means. 
E)  are referred to by the strain O157:H7. B

Question 2

A selective growth medium

Accepted Answer

A)  allows only certain bacteria to grow. 
B)  allows all bacteria to grow. 
C)  allows no bacteria to grow. 
D)  accentuates differences between the growing bacteria. 
E)  is cultured anaerobically. 
A)  allows only certain bacteria to grow. 
B)  allows all bacteria to grow. 
C)  allows no bacteria to grow. 
D)  accentuates differences between the growing bacteria. 
E)  is cultured anaerobically. A

Question 3

Nucleic acid techniques have great power as diagnostic tools because they may be

Accepted Answer

A)  used to differentiate species. 
B)  quick and easy to perform. 
C)  used to enhance the growth of bacteria. 
D)  used to inhibit the growth of certain bacteria. 
E)  All of the answer choices are correct. 
A)  used to differentiate species. 
B)  quick and easy to perform. 
C)  used to enhance the growth of bacteria. 
D)  used to inhibit the growth of certain bacteria. 
E)  All of the answer choices are correct. A

Question 4

A sample must contain many microorganisms in order for them to be seen any using microscopy techniques. Why is this so?

Accepted Answer

A)  The area on a microscope slide is very large compared to the relative size of microbes, and you take a very small amount of your sample to place on the slide surface. Therefore, you must have a large number of microbes initially in the culture to increase the chances that you'll be able to see bacteria on the slide. 
B)  Bacteria are very small. It is only possible to see them if there is a large biofilm of them on the slide. If you don't have a LOT of them, how are you going to see them? 
C)  This statement is misleading. Microscopy allows us to magnify a specimen to the point where we would be able to visualize even just a few microbes on the surface of the slide. Even if there are only a few microbes in a sample, we could easily visualize them with a microscope. 
D)  Microscopes only magnify objects on the slide. If you don't have a lot of microbes on the slide surface, you can't magnify the specimen enough to see them as individual cells. 
E)  When bacteria are placed on a slide, they automatically swarm together into one area of the slide, allowing them to be seen. If there are too few bacteria in the sample, they are unable to swarm effectively and thus cannot be seen, even with staining. 
A)  The area on a microscope slide is very large compared to the relative size of microbes, and you take a very small amount of your sample to place on the slide surface. Therefore, you must have a large number of microbes initially in the culture to increase the chances that you'll be able to see bacteria on the slide. 
B)  Bacteria are very small. It is only possible to see them if there is a large biofilm of them on the slide. If you don't have a LOT of them, how are you going to see them? 
C)  This statement is misleading. Microscopy allows us to magnify a specimen to the point where we would be able to visualize even just a few microbes on the surface of the slide. Even if there are only a few microbes in a sample, we could easily visualize them with a microscope. 
D)  Microscopes only magnify objects on the slide. If you don't have a lot of microbes on the slide surface, you can't magnify the specimen enough to see them as individual cells. 
E)  When bacteria are placed on a slide, they automatically swarm together into one area of the slide, allowing them to be seen. If there are too few bacteria in the sample, they are unable to swarm effectively and thus cannot be seen, even with staining.

Question 5

If each of two bacteria have a GC content of 50%, they are both definitely closely related.

Accepted Answer

A) True 
 B)False

Question 6

Phylogenetic relationships between prokaryotes are most accurately determined using

Accepted Answer

A)  phenotypic characterizations. 
B)  genotypic information. 
C)  the fossil record. 
D)  carbon dating. 
E)  phenotypic characterizations AND genotypic information. 
A)  phenotypic characterizations. 
B)  genotypic information. 
C)  the fossil record. 
D)  carbon dating. 
E)  phenotypic characterizations AND genotypic information.

Question 7

In 1970 Stanier proposed that classification be based on

Accepted Answer

A)  evolution. 
B)  Gram stain. 
C)  physiology. 
D)  DNA sequence. 
E)  flagella. 
A)  evolution. 
B)  Gram stain. 
C)  physiology. 
D)  DNA sequence. 
E)  flagella.

Question 8

Organisms that grow very slowly, cannot be cultured, are present in very small numbers, or are mixed with a number of other bacteria may still be identified using

Accepted Answer

A)  Southern blotting. 
B)  replica plating. 
C)  PCR. 
D)  the Ames test. 
E)  positive selection. 
A)  Southern blotting. 
B)  replica plating. 
C)  PCR. 
D)  the Ames test. 
E)  positive selection.

Question 9

Sequencing of rRNA is useful for

Accepted Answer

A)  determining evolutionary relationships AND determining protein sequences. 
B)  determining protein sequences AND identification of unknown bacteria. 
C)  determining evolutionary relationships AND determining serological relationships. 
D)  determining serological relationships AND determining protein sequences. 
E)  determining evolutionary relationships AND identification of unknown bacteria. 
A)  determining evolutionary relationships AND determining protein sequences. 
B)  determining protein sequences AND identification of unknown bacteria. 
C)  determining evolutionary relationships AND determining serological relationships. 
D)  determining serological relationships AND determining protein sequences. 
E)  determining evolutionary relationships AND identification of unknown bacteria.

Question 10

If you were the lab technician trying to identify the causative organism of this foodborne outbreak, would you inoculate several biochemical tests at the same time, or would you inoculate each test after getting the results from the previous test?

Accepted Answer

A)  I would inoculate each test after obtaining results from the last one because the tests are very quick and give instant results, and doing one test at a time will avoid confusion in the results. 
B)  I would inoculate several tests simultaneously, because most biochemical tests require at least 18 hours of incubation, so inoculating several tests simultaneously saves time and also aids in conclusive identification. 
C)  I would inoculate each test after obtaining results from the last one because the tests are extremely expensive so the fewer tests I can do, the less money I have to invest in the identification process. 
D)  I would inoculate several tests simultaneously, because these tests can only be analyzed using specialized equipment, so I need to have the tests ready at the same time. 
E)  I would inoculate each test after obtaining results from the last one because these tests are very time consuming and difficult to set up, so it would be more practical to take this approach. 
A)  I would inoculate each test after obtaining results from the last one because the tests are very quick and give instant results, and doing one test at a time will avoid confusion in the results. 
B)  I would inoculate several tests simultaneously, because most biochemical tests require at least 18 hours of incubation, so inoculating several tests simultaneously saves time and also aids in conclusive identification. 
C)  I would inoculate each test after obtaining results from the last one because the tests are extremely expensive so the fewer tests I can do, the less money I have to invest in the identification process. 
D)  I would inoculate several tests simultaneously, because these tests can only be analyzed using specialized equipment, so I need to have the tests ready at the same time. 
E)  I would inoculate each test after obtaining results from the last one because these tests are very time consuming and difficult to set up, so it would be more practical to take this approach.

Question 11

A breath test assaying for radioactive carbon dioxide may be used to indicate the presence of

Accepted Answer

A)  E. coli. 
B)  Pseudomonas species. 
C)  Streptococcus pyogenes. 
D)  Helicobacter pylori. 
E)  Bacillus cereus. 
A)  E. coli. 
B)  Pseudomonas species. 
C)  Streptococcus pyogenes. 
D)  Helicobacter pylori. 
E)  Bacillus cereus.

Question 12

Various strains of E. coli

Accepted Answer

A)  may cause disease. 
B)  may be harmless. 
C)  are all exactly the same. 
D)  are all very different from one another. 
E)  may cause disease AND may be harmless. 
A)  may cause disease. 
B)  may be harmless. 
C)  are all exactly the same. 
D)  are all very different from one another. 
E)  may cause disease AND may be harmless.

Question 13

Why are molecular methods particularly useful for identification of microbes that are difficult to grow?

Accepted Answer

A)  While all microbes can (and should) be grown for identification purposes, sometimes it's simply faster to use a molecular technique. 
B)  They AREN'T useful-growing a microbe is clearly the only way to properly identify it. 
C)  Since all microbes have DNA, and we can often detect and identify them through even very small amounts of their DNA, molecular methods allow us to identify microbes even when they can't be grown at all. 
D)  Molecular methods are far cheaper methods than growing microbes for identification. 
A)  While all microbes can (and should) be grown for identification purposes, sometimes it's simply faster to use a molecular technique. 
B)  They AREN'T useful-growing a microbe is clearly the only way to properly identify it. 
C)  Since all microbes have DNA, and we can often detect and identify them through even very small amounts of their DNA, molecular methods allow us to identify microbes even when they can't be grown at all. 
D)  Molecular methods are far cheaper methods than growing microbes for identification.

Question 14

In E. coli O157:H7, the O157:H7 refers to the

Accepted Answer

A)  specific type of DNA present. 
B)  specific genus. 
C)  general family. 
D)  the specific LPS and flagella type present. 
E)  pathogenic ability. 
A)  specific type of DNA present. 
B)  specific genus. 
C)  general family. 
D)  the specific LPS and flagella type present. 
E)  pathogenic ability.

Question 15

E. coli 0157:H7 produces clear colonies on MacConkey agar, while common strains of the organism produce pink colonies on this medium. The organism stains pink in the Gram stain. Select the TRUE statement, given this information.

Accepted Answer

A)  E. coli 0157:H7 is Gram-positive AND is a normal constituent of the intestinal tract. 
B)  E. coli 0157:H7 is a normal constituent of the intestinal tract AND does not ferment sorbitol. 
C)  E. coli 0157:H7 does not ferment sorbitol AND is Gram negative. 
D)  E. coli 0157:H7 does not ferment sorbitol AND is Gram-positive. 
E)  E. coli 0157:H7 produces a toxin AND is a normal constituent of the intestinal tract. 
A)  E. coli 0157:H7 is Gram-positive AND is a normal constituent of the intestinal tract. 
B)  E. coli 0157:H7 is a normal constituent of the intestinal tract AND does not ferment sorbitol. 
C)  E. coli 0157:H7 does not ferment sorbitol AND is Gram negative. 
D)  E. coli 0157:H7 does not ferment sorbitol AND is Gram-positive. 
E)  E. coli 0157:H7 produces a toxin AND is a normal constituent of the intestinal tract.

Question 16

The basic taxonomic unit in the classification scheme of plants and animals is

Accepted Answer

A)  kingdom. 
B)  class. 
C)  order. 
D)  genus. 
E)  species. 
A)  kingdom. 
B)  class. 
C)  order. 
D)  genus. 
E)  species.

Question 17

APITM, EnterotubeTM, and VitekTM are all

Accepted Answer

A)  methods for extracting DNA from bacteria. 
B)  used to measure gas production. 
C)  commercially available methods used to identify bacteria. 
D)  used to show the presence of bacteria in a sample. 
E)  methods for extracting protein from bacteria. 
A)  methods for extracting DNA from bacteria. 
B)  used to measure gas production. 
C)  commercially available methods used to identify bacteria. 
D)  used to show the presence of bacteria in a sample. 
E)  methods for extracting protein from bacteria.

Question 18

Strain differences are helpful in

Accepted Answer

A)  understanding replica plating. 
B)  carrying out electrophoresis. 
C)  performing transformation in the laboratory. 
D)  initiating transduction in E. coli. 
E)  tracing the source of outbreaks of disease. 
A)  understanding replica plating. 
B)  carrying out electrophoresis. 
C)  performing transformation in the laboratory. 
D)  initiating transduction in E. coli. 
E)  tracing the source of outbreaks of disease.

Question 19

You are sent three clinical samples and are asked to determine whether they are the same strain. You perform standard identification techniques but cannot come to a conclusion. You decide to do an RFLP test. You digest the genomes of the organisms with the same restriction enzyme and run a gel. Each organism yields 5 bands on the gel, of the following sizes:
Organism A: 3 kb, 7 kb, 11 kb; 14 kb, 21 kb; Organism B: 3 kb, 7 kb, 2 kb, 8 kb, 11 kb; Organism C: 11 kb, 3 kb, 14 kb, 7 kb; 21 kb
What conclusion(s) can you make from this result?

Accepted Answer

A)  Organisms A and B are likely the same strain but are different from organism C. 
B)  Organisms B and C are likely the same strain but are different from organism A. 
C)  Organisms A and C are likely the same strain but are different from organism B. 
D)  The organisms are all likely the same strain. 
E)  The organisms are all likely different strains. 
A)  Organisms A and B are likely the same strain but are different from organism C. 
B)  Organisms B and C are likely the same strain but are different from organism A. 
C)  Organisms A and C are likely the same strain but are different from organism B. 
D)  The organisms are all likely the same strain. 
E)  The organisms are all likely different strains.

Question 20

When DNA probes are used to identify bacterial DNA similarities by hybridization, the probe DNA is heated and the template DNA is treated to separate the two strands. Why would the probe DNA be heated?

Accepted Answer

A)  This is the only way to properly label the probe DNA. 
B)  The probe may contain parts that are double-stranded. Heating it up breaks the hydrogen bonds holding the strands together, creating single-stranded sequences that hybridize with their complementary targets. 
C)  Heating it up activates the tag on the probe DNA before it hybridizes to the bacterial template DNA. 
D)  DNA hybridization can only take place at high temperatures, so all the DNA must be heated up prior to hybridization. 
E)  The probe may contain many parts that are single-stranded. Heating it up creates hydrogen bonds that hold the probe tightly to its complementary target sequences. 
A)  This is the only way to properly label the probe DNA. 
B)  The probe may contain parts that are double-stranded. Heating it up breaks the hydrogen bonds holding the strands together, creating single-stranded sequences that hybridize with their complementary targets. 
C)  Heating it up activates the tag on the probe DNA before it hybridizes to the bacterial template DNA. 
D)  DNA hybridization can only take place at high temperatures, so all the DNA must be heated up prior to hybridization. 
E)  The probe may contain many parts that are single-stranded. Heating it up creates hydrogen bonds that hold the probe tightly to its complementary target sequences.

Exam 10: Identifying and Classifying Microorganisms

Phenotypically identical bacteria

A selective growth medium

Nucleic acid techniques have great power as diagnostic tools because they may be

A sample must contain many microorganisms in order for them to be seen any using microscopy techniques. Why is this so?

If each of two bacteria have a GC content of 50%, they are both definitely closely related.

Phylogenetic relationships between prokaryotes are most accurately determined using

In 1970 Stanier proposed that classification be based on

Organisms that grow very slowly, cannot be cultured, are present in very small numbers, or are mixed with a number of other bacteria may still be identified using

Sequencing of rRNA is useful for

If you were the lab technician trying to identify the causative organism of this foodborne outbreak, would you inoculate several biochemical tests at the same time, or would you inoculate each test after getting the results from the previous test?

A breath test assaying for radioactive carbon dioxide may be used to indicate the presence of

Various strains of E. coli

Why are molecular methods particularly useful for identification of microbes that are difficult to grow?

In E. coli O157:H7, the O157:H7 refers to the

E. coli 0157:H7 produces clear colonies on MacConkey agar, while common strains of the organism produce pink colonies on this medium. The organism stains pink in the Gram stain. Select the TRUE statement, given this information.

The basic taxonomic unit in the classification scheme of plants and animals is

APITM, EnterotubeTM, and VitekTM are all

Strain differences are helpful in

When DNA probes are used to identify bacterial DNA similarities by hybridization, the probe DNA is heated and the template DNA is treated to separate the two strands. Why would the probe DNA be heated?

Humans and the Microbial World

The Molecules of Life

Microscopy and Cell Structure

Dynamics of Microbial Growth

Control of Microbial Growth

Microbial Metabolism: Fueling Cell Growth

The Blueprint of Life, From Dna to Protein

Bacterial Genetics

Biotechnology

The Diversity of Bacteria and Archaea

The Eukaryotic Members of the Microbial World

Viruses, Viroids, and Prions

The Innate Immune Response

The Adaptive Immune Response

Host-Microbe Interactions

Immunological Disorders

Applications of Immune Responses

Epidemiology

Antimicrobial Medications

Respiratory System Infections

Skin Infections

Wound Infections

Digestive System Infections

Blood and Lymphatic Infections

Nervous System Infections

Genitourinary Tract Infections

Microbial Ecology

Environmental Microbiology: Treatment of Water, Wastes, and Polluted Habitats

Food Microbiology

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