Microbiology 154 Exam 3 Review

Question 1

A molecular clock for evolution is based on

a. Fossil records for organisms
b. Cellular structures of organisms
c. Nucleotide sequences in the genomes of organisms
d. Enzymatic activities of organisms

Answer 1

c. Nucleotide sequences in the genomes of organisms

Question 2

Woese developed the three-domain system based on differences organisms’

a. Cell morphologies
b. rRNA sequences
c. Gram stain reactions
d. habitats

Answer 2

b. rRNA sequences

Question 3

In the scientific name Staphylococcus aureus, Staphylococcus is the

a. Class
b. Genus
c. Specific epithet
d. Family

Answer 3

b. Genus

Question 4

A prokaryotic species is defined as a

a. Population of cells with similar characteristics
b. Population of cells with different characteristics
c. Group of closely related organisms that can interbreed
d. Group of organisms that are not composed of cells

Answer 4

a. Population of cells with similar characteristics

Question 5

Treating DNA from different bacteria with the same restriction enzyme followed by separation of the fragments by electrophoresis is known as

a. DNA base composition
b. DNA fingerprinting
c. The nucleic acid amplification test (NAAT)
d. Ribotyping

Answer 5

b. DNA fingerprinting

Question 6

A person who has measles will develop ________ immunity.

a. Naturally acquired active
b. Naturally acquired passive
c. Artificially acquired active
d. Artificially acquired passive

Answer 6

a. Naturally acquired active

Question 7

Plasma cells are formed after the proliferation of which type of cell?

a. B cell
b. T cell
c. Dendritic cell
d. Macrophage

Answer 7

a. B cell

Question 8

Generally, antibodies recognize and interact with specific regions on antigens called

a. PAMPs
b. Haptens
c. Epitopes
d. Active sites

Answer 8

c. Epitopes

Question 9

Phagocytes contain ________ that allow attachment of pathogens.

a. Antibodies
b. Toll-like receptors
c. Spikes
d. PAMPs

Answer 9

b. Toll-like receptors

Question 10

During ingestion, pseudopods of a phagocyte fuse, surrounding the microorganism in a(n)

a. Phagosome
b. Granule
c. Inclusion body
d. Histiocyte

Answer 10

a. Phagosome

Question 11

Which of the following is an example of the epidemiological triangle?

a. a bat infecting a human with ebola virus
b. a disease carried from one continent to another where it then becomes prevalent
c. locating three cases of a diseases to estimate the center of the outbreak
d. an opportunistic pathogen like clostridium difficile infecting an immune-compromised patient

Answer 11

a. a bat infecting a human with Ebola virus

Question 12

which of the following statements about innate immunity is FALSE?

a. the innate immune system recognizes general characteristics of foreign organisms
b. the innate system lacks “memory” and does not respond more vigorously when a foreign organism invades the body second time
c. the innate immune system is a surveillance system that is induced when an infection occurs
d. the innate immune system does not confer long-lasting immunity

Answer 12

c. the innate immune system is a surveillance system that is induced when an infection occurs

Question 13

what best describes an endemic disease?

a) a disease that occurs only occasionally
b) a disease constantly present in a population
c) a disease acquired by many people in a given area in a short time
d) a worldwide epidemic

Answer 13

b. a disease constantly present in a population

Question 14

Which of the following are early examples of epidemiology?

a) John Snow collecting cholera surveillance data and shutting down the Broad Street pump in London
b) Ignaz Semmelweis forcing doctors and interns to wash their hands in his surgical ward to reduce the incidence of puerperal fever
c) Alexander Fleming demonstrating that Penicillium rubens exuded a substance with antibiotic properties
d) (a) and (b)
e) All of the above

Answer 14

d. (a) and (b)

Question 15

Which of these diseases is zoonotic?

a) Plague
b) Influenza A
c) Measles
d) HIV

Answer 15

a) plague

Question 16

Which of the following statements about macrophages is FALSE?

a) Macrophages have pattern recognition receptors (PRRs) that recognize molecules that are broadly shared by pathogens (PAMPS) but distinguishable from host molecules.
b) The LPS of Gram negative bacteria and teichoic acids of Gram positive bacteria are examples of PAMPs.
c) Macrophages stimulate the production of antibodies that are specific for a particular pathogen
d) Macrophages can ingest, kill and digest invading microorganisms

Answer 16

c) Macrophages stimulate the production of antibodies that are specific for a particular pathogen

Question 17

Antibodies

a) are very specific and can identify a particular microbe with high precision.
b) are produced in response to vaccines
c) function as opsonins and enhance phagocytosis
d) all of the above.

Answer 17

d) all of the above

Question 18

Which of the following help protect humans and other animals against infectious diseases?

a) the adaptive immune system
b) the innate immune system
c) mechanical defenses
d) only (a) and (b)
e) all of the above (a, b and c)

Answer 18

e) all of the above (a, b, and c)

Question 19

Which part of Ebola virus is the target of neutralizing antibodies?

a) glycoprotein
b) DNA polymerase
c) nucleocapsid
d) lipid envelope
e) viral genome

Answer 19

a) glycoprotein

Question 20

Which of the following statements about vaccines is FALSE?

a) vaccines cause antibodies to be produced that specifically target a specific pathogen
b) vaccines are sometimes based on attenuated live organisms
c) vaccines cause autism
d) vaccination is a highly effective way to prevent infectious diseases

Answer 20

c) vaccines cause autism

Question 21

Immunological ‘memory’

a) helps the immune system respond more rapidly to infectious agents
b) is a key reason why vaccines are effective
c) is usually not effective
d) only (a) and (b)
e) all of the above (a, b and c)

Answer 21

d) only (a) and (b)

Question 22

In recent years there have been an increased incidence of measles in the United States. This is thought to be largely because

a) antibiotic resistance has become more wide-spread
b) people travel abroad more than they used to
c) an increasing number of people have not been vaccinated against measles
d) the average age of people in the United States has decreased

Answer 22

c) an increasing number of people have not been vaccinated against measles

Question 23

Which of the following statements about tuberculosis is TRUE

a) the increased incidence of antibiotic resistance in Mycobacterium tuberculosis is an emerging health care crisis.
b) it has only recently become a common disease
c) has become much more common in the United States because the incidence of HIV has increased
d) it is only found in people with HIV

Answer 23

a) the increased incidence of antibiotic resistance in Mycobacterium tuberculosis is an emerging health care crisis.

Question 24

Which of the following statements is FALSE

a) the gut microbiome ‘communicates’ with the human brain
b) the gut microbiome can be dramatically affected by antibiotics
c) the gut microbiome does not change much after an individual is born d) none of these statements are false

Answer 24

d) none of these statements are false

Question 25

People living with HIV are 20 to 30 times more likely to develop tuberculosis than people without HIV. Why?

a) they are likely to be socioeconomically disadvantaged and do not have ready access to adequate health care
b) their immune systems can not function as well as those of healthy individuals
c) they are more likely to be exposed to people infected by Mycobacterium tuberculosis
d) all of the above

Answer 25

b) their immune systems can not function as well as those of healthy individuals

Question 26

Which of the following is not true about oxygen

a) Is always used as a terminal electron acceptor in bacterial metabolism
b) Required for strictly aerobic bacteria
c) Can be toxic or lethal to some organisms
d) Toxicity mostly due to the production of superoxide radicals that are powerful oxidizing agents
e) Aerobic bacteria can protect themselves but strict anaerobes can not

Answer 26

a) Is always used as a terminal electron acceptor in bacterial metabolism

Question 27

A metagenome

a) consists of all the mRNA molecules in a single species
b) consists of all the genome sequences present in a microbial community
c) consists of all the mRNA sequences in a microbial community
d) is determined by the DNA sequence of a bacterial genome

Answer 27

b) consists of all the genome sequences present in a microbial community

Question 28

“Cultivation-independent” methods

a) are used once the organisms in a microbial community have been isolated and pure cultures have been obtained
b) are commonly used to determine microbial community structure and function
c) only provide information about the genome sequences of the bacterial species present in a community
d) all of the above are true statements

Answer 28

b) are commonly used to determine microbial community structure and function
c) only provide information about the genome sequences of the bacterial species present in a community

Question 29

The human microbiome
a) includes all the bacterial species that reside in the gut and elsewhere in and on your
body
b) includes thousands of bacterial species
c) markedly varies between individuals
d) all of the above are true

Answer 29

d) all of the above are true

Question 30

The vaginal pH of healthy women

a) is always less than 4.5
b) is almost the same in all reproductive age women
c) is the same among females of all ages
d) is usually acidic because of lactic acid produced by bacteria
e) these are all true statements

Answer 30

d) is usually acidic because of lactic acid produced by bacteria

Question 31

Bacterial communities in the human vagina

a) are comprised of many bacterial species
b) have high numbers of bacterial cells
c) vary over time in almost all reproductive age women
d) all of the above are true statements

Answer 31

d) all of the above are true statements

Question 32

The degree of pathogenicity of an organism is known as the

a) antigenicity.
b) toxigenicity.
c) virulence.
d) cytopathic effect.

Answer 32

c) virulence.

Question 33

Antibiotics that kill bacteria are

a) referred to as bactericidal antibiotics
b) referred to as bacteriostatic antibiotics
c) not effective in treating infections
d) commonly used because they also kill eukaryotic cells

Answer 33

a) referred to as bactericidal antibiotics

Question 34

The antibiotics commonly used to treat bacterial infections

a) always act by inhibiting the cross linking of polysaccharides in bacterial cell walls
b) always act by inhibiting bacterial protein synthesis
c) inhibit various biochemical processes that occur in both prokaryotes and eukaryotes
d) none of the above

Answer 34

d) none of the above

Question 35

Which of the following statements about penicillins and cephalosporins are not true:

a) they have entirely different chemical structures
b) they inhibit bacterial cell wall synthesis
c) they have largely different chemical structures, but all have beta-lactam rings
d) they specifically inhibit the growth of prokaryotes

Answer 35

a) they have entirely different chemical structures

Question 36

Antibiotic resistance in bacteria

a) develops as a result of spontaneous mutations
b) is readily transferred among various bacterial species by horizontal gene transfer
c) is often encoded on plasmids
d) all of the above

Answer 36

d) all of the above

Question 37

Tuberculosis (TB) is:

a) readily cured by treating ill persons with antibiotics.
b) second only to HIV/AIDS as the greatest killer worldwide due to a single infectious agent.
c) not a problem in the world today because there is an effective vaccine.
d) is only a problem in the developing world where there is inadequate health care infrastructure.

Answer 37

b) second only to HIV/AIDS as the greatest killer worldwide due to a single infectious agent.

Question 38

Exotoxins are:
a) lipopolysaccharides (LPS) found on the surface of some bacteria.
b) proteins made by pathogenic bacteria that are virulence determinants.
c) molecules that are embedded in the S layer of Gram-positive pathogenic bacteria that
cause fever during infectious disease.
d) none of these statements are correct.

Answer 38

b) proteins made by pathogenic bacteria that are virulence determinants.

Question 39

The “targets” for antibiotics used to treat bacterial infections are:

a) found only in pathogenic microorganisms.
b) are only various steps in protein biosynthesis.
c) biochemical processes that are only found in bacteria and not eukaryotic hosts.
d) statements (a) and (c) are both correct.

Answer 39

c) biochemical processes that are only found in bacteria and not eukaryotic hosts.

Question 40

Bactericidal compounds

a) Are agents that stop bacteria from reproducing, while not necessarily killing them
b) Are agents that slow the growth of bacteria
c) Are agents that kill bacteria
d) Are agents that clean remove bacteria from surfaces

Answer 40

c) Are agents that kill bacteria

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Question 41

Beta-lactam antibiotics:
a) inhibit protein synthesis.
b) include penicillins and cephalosporins.
c) inhibit the transpeptidase that crosslinks N-acetylglucosamine and N-acetylmuramic
acid, which are polysaccharides found in bacterial cell walls.
d) statements (a) and (b) are both correct.
e) statements (b) and (c) are both correct.

Answer 41

e) statements (b) and (c) are both correct.

Question 42

Resistance to antibiotics:

a) often spreads through horizontal gene transfer.
b) develops only in pathogenic microorganisms.
c) develops through mutation and selection.
d) statements (a) and (c) are both correct.
e) answers (a), (b) and (c) are all correct.

Answer 42

d) statements (a) and (c) are both correct.

Question 43

If an antibiotic prevents bacteria from growing, then its action is termed

a) bactericidal.
b) selectively toxic.
c) bacteriostatic.
d) toxic.

Answer 43

c) bacteriostatic.

Question 44

To cause an infectious disease in humans a pathogen must first:

a) breach the host’s physical and chemical barriers.
b) survive the host’s innate defense mechanisms.
c) surmount the host’s adaptive immunity.
d) all of the statements above are correct.
e) none of the statements above are correct.

Answer 44

d) all of the statements above are correct.

Question 45

The innate immune system:
a) includes antibodies that recognize structural features commonly found on pathogens
and other foreign bodies.
b) is nonspecific and largely relies on phagocytes and dendritic cells to engulf and destroy
pathogens and other foreign bodies.
c) provides an immediate defense against infection.
d) statements (a) and (c) are both correct.
e) statements (b) and (c) are both correct.

Answer 45

e) statements (b) and (c) are both correct.

Question 46

Multiple drug resistant (MDR) bacteria:
a) occur in various places around the world, but they rarely spread.
b) pose a major challenge to health care providers because they are difficult to treat with
antibiotics.
c) only occur in hospitals where antibiotics are very commonly used.
d) all of the statements above are correct.

Answer 46

b) pose a major challenge to health care providers because they are difficult to treat with
antibiotics.

Question 47

The human microbiome

a) includes all the microorganisms that live in and on the human body.
b) is thought to constitute 1-3% of a person’s body weight.
c) is estimated to include thousands of bacterial species.
d) statements (a), (b) and (c) are all correct.
e) only statements (a) and (b) are correct.

Answer 47

d) statements (a), (b) and (c) are all correct.

e) only statements (a) and

Question 48

In healthy reproductive age women the vagina:
a) is acidic and always has a pH < 4.5.
b) always has high proportions of lactobacilli.
c) has more or less the same bacteria except during menses when the species
composition of the community markedly changes.
d) statements (a), (b) and (c) are all correct.
e) statements (a), (b) and (c) are all not correct.

Answer 48

d) statements (a), (b) and (c) are all correct.

Question 49

Antigens are:
a) molecules that elicit the synthesis of antibodies that specifically bind the antigen.
b) molecules produced by the host that bind to pathogens and target them for
phagocytosis.
c) components of vaccines.
d) statements (a) and (c) are both correct.
e) statements (b) and (c) are both correct.

Answer 49

d) statements (a) and (c) are both correct.

Question 50

Fecal transplants involve transplanting fecal bacteria from one healthy individual to another who is suffering from a severe intestinal disorder. Which of the following statements are true?

a) they are always used to prevent the occurrence of severe intestinal disorders
b) they are scientifically sound but not done because the risk of infection is too high.
c) they have been used to successfully treat Crohn’s disease and inflammatory bowel disease.
d) they are not effective because the bacteria of the gastrointestinal tract are uniquely adapted to an individual and competitively exclude the donor’s bacteria.

Answer 50

c) they have been used to successfully treat Crohn’s disease and inflammatory bowel disease.

Question 51

Which of the following statements about human papilloma virus (HPV) infections are not true:

a) HPV is an important cause of cervical cancer.
b) 80% of people in the United States are likely to be infected by HPV during their lifetime.
c) HPV infections only occur in individuals who have AIDS.
d) HPV can be transmitted through sexual intercourse.
e) both men and women can be vaccinated and acquire immunity to most strains of HPV.

Answer 51

c) HPV infections only occur in individuals who have AIDS.

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Question 52

Which step in the Ebola virus replication cycle is mediated by glycoprotein (GP)?

a) attachment to the host cell.
b) uncoating of the viral genome during entry.
c) replication of the viral RNA.
d) statements (a) and (b) are both correct.
e) statements (a), (b), and (c) are all correct.

Answer 52

a) attachment to the host cell.

Question 53

Adaptive evolution can be investigated by:

a) comparing gene sequences across genomes.
b) experimental evolution studies done in laboratories.
c) the study of microorganisms growing in strongly selective environments.
d) all of the approaches listed above.
e) none of the approaches listed above.

Answer 53

d) all of the approaches listed above.

Question 54

Bacteria and Archaea play a central role in the global carbon cycle because:
a) some species of Bacteria can fix carbon dioxide through photosynthesis.
b) because only some species of Archaea can produce methane.
c) they have important roles in the metabolism of organic matter in terrestrial and aquatic
environments.
d) statements (b) and (c) are both correct.
e) statements (a), (b) and (c) are all correct.

Answer 54

e) statements (a), (b) and (c) are all correct.

Question 55

Studies on the microbiology of the ‘built environment’ have shown:

a) the air-borne bacteria are the same throughout a building.
b) the air-borne bacteria in a building vary from one part of a building to another.
c) the air-borne bacteria in a building are the same as those found outside the building.
d) the air-borne bacteria are the same throughout a building, but different than those found outside the building.

Answer 55

d) the air-borne bacteria are the same throughout a building, but different than those found outside the building.

Question 56

Some species of Bacteria and Archaea:
a) have key roles in the Earth’s biogeochemical cycles
b) can use inorganic molecules other than oxygen as terminal electron acceptors
c) are unique among all living organisms because they can ‘fix’ nitrogen by reducing
nitrogen gas to ammonia
d) all of the above.

Answer 56

d) all of the above.

Question 57

Which of the following statements about biogeochemical cycles is NOT true?
a) Many key elements (ex. C, N, S) are used as electron donors or electron acceptors by
prokaryotes
b) Processes are not carried out by Eukaryotes
c) Forms of many key elements (ex. C, N, S) are ‘recycled’ in processes that are essential
for all life forms, including plants and animals
d) These processes are only done by Bacteria and Archaea are not involved.

Answer 57

d) These processes are only done by Bacteria and Archaea are not involved.

Question 58

Enveloped viruses obtain a lipid bilayer from the host cell in which the virus replicates.

a) True
b) False

Answer 58

a) True

Question 59

Which of the following does not relate to the phenetic species concept?

a) Provides a hierarchical classification
b) Organisms assigned to categories based on diagnostic characteristics
c) Relies on analysis of DNA sequences
d) Organisms are given binomial names
e) Genus species; example: Staphylococcus aureus

Answer 59

c) Relies on analysis of DNA sequences

Question 60

Carl Woese proposed the three-domain system based on differences in organisms’

a) cell morphologies.
b) rRNA sequences.
c) Gram stain reactions.
d) habitats.

Answer 60

b) rRNA sequences.

Question 61

A prokaryotic species is defined as a

a) population of cells with similar characteristics.
b) population of cells with different characteristics.
c) group of closely related organisms that can interbreed.
d) group of organisms that are not composed of cells.

Answer 61

a) population of cells with similar characteristics.

Question 62

Historically living things were classified into five kingdoms (Monera, Protista, Fungi, Plantae and Animalia). Nowadays, living things are classified into domains. How many are there?

a) 5
b) 4
c) 3
d) 2

Answer 62

c) 3

Question 63

Which of the following is not a method that was historically used to classify and identify microorganisms?

a) morphological characteristics of cells
b) differential staining (ex. Gram staining, acid-fast stain)
c) sequencing of 16S and 18S rRNA genes
d) biochemical tests to determine presence of bacterial enzymes

Answer 63

c) sequencing of 16S and 18S rRNA genes

Question 64

Etiology is

a) an abnormal state in which the body is incapable of performing some normal functions
b) the study of disease
c) the structural and functional changes in organisms that are caused by disease
d) the cause of diseases and disorders
e) the manner in which disease develops

Answer 64

d) the cause of diseases and disorders

Question 65

Normal microbiota provide protection from infection in each of the following ways EXCEPT

a) they produce antibacterial chemicals.
b) they compete with pathogens for nutrients.
c) they make the chemical environment unsuitable for nonresident bacteria.
d) they produce lysozyme.

Answer 65

d) they produce lysozyme.

Question 66

Lysozyme and the antibiotic penicillin have similar mechanisms of action in that they both cause damage to the bacterial

a) cell membrane.
b) capsule.
c) cell wall.
d) DNA.
e) ribosomes.

Answer 66

c) cell wall

Question 67

Which of the following do NOT fix atmospheric nitrogen?

a) cyanobacteria
b) lichens
c) mycorrhizae
d) Rhizobium

Answer 67

c) mycorrhizae

Question 68

The oxidation of ammonia to produce nitrate is known as

a) denitrification.
b) nitrogen fixation.
c) ammonification.
d) nitrification.

Answer 68

d) nitrification.

Question 69

Which process converts nitrate into gaseous nitrogen?

a) denitrification
b) nitrogen fixation
c) ammonification
d) nitrification

Answer 69

b) nitrogen fixation

Question 70

Penicillin works by inhibiting ________ synthesis.

a) protein
b) cell wall
c) plasma membrane
d) nucleic acid

Answer 70

b) cell wall

Question 71

Bacteria that are resistant to large numbers of antibiotics are popularly termed

a) superbugs.
b) superinfections.
c) MRSA.
d) mutants

Answer 71

a) superbugs.

Question 72

If one measures a large zone of inhibition in a disk-diffusion test, one can assume that the bacteria are

a) sensitive to the antibiotic.
b) resistant to the antibiotic.
c) unaffected by the antibiotic.
d) producing the antibiotic.

Answer 72

a) sensitive to the antibiotic.

Question 73

Which of the following is/are NOT a first line of defense?

a) skin
b) tears
c) saliva
d) fever

Answer 73

d) fever

Question 74

Which white blood cell dominates during the initial phase of a bacterial infection?

a) neutrophil
b) monocyte
c) lymphocyte
d) eosinophil

Answer 74

d) eosinophil

Question 75

During ingestion, pseudopods of a phagocyte fuse, surrounding the microorganism in a(n)

a) phagosome.
b) granule.
c) inclusion body.
d) histiocyte.

Answer 75

a) phagosome

Question 76

Grouping organisms into categories to show degrees of similarities is called

a) systematics.
b) taxonomy.
c) hierarchy.
d) nomenclature.

Answer 76

b) taxonomy.

Question 77

Which of the following statements describes the Domain Bacteria?

a) They are multicellular.
b) They have linear chromosomes.
c) They have prokaryotic cells.
d) They have eukaryotic cells

Answer 77

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Question 78

A molecular clock for evolution is based on

a) fossil records of organisms.
b) cellular structures of organisms.
c) nucleotide sequences in the genomes of organisms.
d) enzymatic activities of organisms.

Answer 78

c) nucleotide sequences in the genomes of organisms.

Question 79

A clone is

a) the same as a species.
b) a population of cells with similar characteristics.
c) a freely interbreeding population.
d) a population of cells derived from a single parent cell.

Answer 79

d) a population of cells derived from a single parent cell.

Question 80

In the scientific name Staphylococcus aureus, Staphylococcus is the

a) class.
b) genus.
c) specific epithet.
d) family.

Answer 80

b) genus

Question 81

A prokaryotic species is defined as a

a) population of cells with similar characteristics.
b) population of cells with different characteristics.
c) group of closely related organisms that can interbreed.
d) group of organisms that are not composed of cells.

Answer 81

a) population of cells with similar characteristics.

Question 82

Fossil evidence indicates that prokaryotic cells first existed on Earth ________ years ago.

a) 3.5 billion
b) 3.5 million
c) 350,000
d) 3500

Answer 82

a) 3.5 billion

Question 83

Historically, eukaryotic organisms that did NOT fit into other kingdoms were placed into which kingdom?

a) Protista
b) Fungi
c) Plantae
d) Animalia

Answer 83

a) Protista

Question 84

Treating DNA from different bacteria with the same restriction enzyme followed by separation of
the fragments by electrophoresis is known as:
a) DNA base composition.
b) DNA fingerprinting.
c) the nucleic acid amplification test (NAAT).
d) ribotyping.

Answer 84

b) DNA fingerprinting.