Question 1

High concentrations of some bacteria are necessary for successful invasion because their virulence genes are only expressed at high population densities.

Accepted Answer

A) True 
 B)False  True

Question 2

A human fetus has no resident microbial population.

Accepted Answer

A) True 
 B)False  True

Question 3

People who carry and may spread pathogenic organisms without any apparent signs or symptoms of illness are called

Accepted Answer

A)  carriers. 
B)  primary infectors. 
C)  secondary infectors. 
D)  mutualists. 
E)  opportunists. 
A)  carriers. 
B)  primary infectors. 
C)  secondary infectors. 
D)  mutualists. 
E)  opportunists. A

Question 4

Which of the following members of the normal microbiota inhibit the growth of Candida albicans?

Accepted Answer

A)  E. coli 
B)  Lactobacillus species 
C)  Staphylococci species 
D)  Propionibacterium species 
E)  All of the answer choices are correct. 
A)  E. coli 
B)  Lactobacillus species 
C)  Staphylococci species 
D)  Propionibacterium species 
E)  All of the answer choices are correct.

Question 5

The composition of the normal microbiota may be affected by

Accepted Answer

A)  hormonal changes. 
B)  use of antibiotics. 
C)  obesity level. 
D)  diet. 
E)  All of the choices are correct. 
A)  hormonal changes. 
B)  use of antibiotics. 
C)  obesity level. 
D)  diet. 
E)  All of the choices are correct.

Question 6

In two of Koch's postulates (#2 and #3), a pure culture of the organism is required. Which of the following would NOT be a possible consequence of using a contaminated culture?

Accepted Answer

A)  You can't necessarily attribute the illness directly to the microbe in question; it may in fact be caused by the contaminating microbe. 
B)  There's the possibility that the test animal might be acutely susceptible to the contaminating microbe, but completely resistant to the microbe you suspect causes the illness of interest. As such, when you introduce it into the test animal, it could confuse your final results. 
C)  Even though there's a contaminating microbe present, as long as the original suspect microbe is also present, the disease should still manifest in test animals and the organism should still be recoverable from test animals. As such, there's really no consequence to using a contaminated culture. 
D)  The problem is that one microbe may be toxic to the other. It may have killed all of your suspect microbe in the culture. Therefore, you can't be sure that you're infecting your test animals with the microbe you suspect is causing the illness, or if it's only the second (contaminating) microbe. 
E)  These would all be consequences of using contaminated cultures. 
A)  You can't necessarily attribute the illness directly to the microbe in question; it may in fact be caused by the contaminating microbe. 
B)  There's the possibility that the test animal might be acutely susceptible to the contaminating microbe, but completely resistant to the microbe you suspect causes the illness of interest. As such, when you introduce it into the test animal, it could confuse your final results. 
C)  Even though there's a contaminating microbe present, as long as the original suspect microbe is also present, the disease should still manifest in test animals and the organism should still be recoverable from test animals. As such, there's really no consequence to using a contaminated culture. 
D)  The problem is that one microbe may be toxic to the other. It may have killed all of your suspect microbe in the culture. Therefore, you can't be sure that you're infecting your test animals with the microbe you suspect is causing the illness, or if it's only the second (contaminating) microbe. 
E)  These would all be consequences of using contaminated cultures.

Question 7

The infectious dose of most pathogens is about equal.

Accepted Answer

A) True 
 B)False

Question 8

Species of both Shigella and Streptococcus

Accepted Answer

A)  invade host cells AND cause a rash. 
B)  produce a toxin AND cause a rash. 
C)  cause diarrhea AND are delivered by flea bites. 
D)  are delivered via flea bites AND produce a toxin. 
E)  invade host cells AND produce a toxin. 
A)  invade host cells AND cause a rash. 
B)  produce a toxin AND cause a rash. 
C)  cause diarrhea AND are delivered by flea bites. 
D)  are delivered via flea bites AND produce a toxin. 
E)  invade host cells AND produce a toxin.

Question 9

The length of the incubation period depends on a variety of factors, including

Accepted Answer

A)  the growth rate of the pathogen AND environmental conditions. 
B)  the host's condition AND the carrier's vaccination status. 
C)  number of infectious cells or virions encountered AND the host's condition. 
D)  number of infectious cells or virions encountered, the host's condition, AND the growth rate of the pathogen. 
E)  the growth rate of the pathogen only. 
A)  the growth rate of the pathogen AND environmental conditions. 
B)  the host's condition AND the carrier's vaccination status. 
C)  number of infectious cells or virions encountered AND the host's condition. 
D)  number of infectious cells or virions encountered, the host's condition, AND the growth rate of the pathogen. 
E)  the growth rate of the pathogen only.

Question 10

An example of genetic variation used in pathogen survival may be

Accepted Answer

A)  preventing encounters with phagocytes. 
B)  avoid the killing effects of complement system proteins. 
C)  changing the pilus type. 
D)  surviving within a phagocyte. 
E)  protease production. 
A)  preventing encounters with phagocytes. 
B)  avoid the killing effects of complement system proteins. 
C)  changing the pilus type. 
D)  surviving within a phagocyte. 
E)  protease production.

Question 11

Is it a good strategy for a microbe to adhere to a receptor that plays a critical function for a host cell?

Accepted Answer

A)  No, it ISN'T a good strategy. Host cells could use an alternative receptor and shut down production of the main receptor. The microbe would not have anything to attach to and the cell would thus prevent infection. 
B)  Yes, it IS a good strategy. If it's a receptor the cell MUST use, it doesn't have an alternative receptor to switch to, so even though that receptor makes the cell susceptible to infection, it HAS to put that target out there. This benefits the microbe. 
C)  No, it ISN'T a good strategy. Microbes need to evade detection and elimination by the immune system. If they adhere to a receptor that plays a critical function, they are less likely to trigger destructive immune responses. This would be similar to using a hostage as a shield in a police-standoff situation. 
D)  No, it ISN'T a good strategy. By binding to receptors, the microbes will be phagocytosed by cells and destroyed within them, thus failing to infect the host cell. 
E)  Yes, it IS a good strategy. If the microbe attaches to a critical receptor, the host cell will be forced to try to rid itself of the pathogen. One way it can do this is to phagocytose the pathogen, thereby taking it into its own nucleus, which benefits the pathogen. 
A)  No, it ISN'T a good strategy. Host cells could use an alternative receptor and shut down production of the main receptor. The microbe would not have anything to attach to and the cell would thus prevent infection. 
B)  Yes, it IS a good strategy. If it's a receptor the cell MUST use, it doesn't have an alternative receptor to switch to, so even though that receptor makes the cell susceptible to infection, it HAS to put that target out there. This benefits the microbe. 
C)  No, it ISN'T a good strategy. Microbes need to evade detection and elimination by the immune system. If they adhere to a receptor that plays a critical function, they are less likely to trigger destructive immune responses. This would be similar to using a hostage as a shield in a police-standoff situation. 
D)  No, it ISN'T a good strategy. By binding to receptors, the microbes will be phagocytosed by cells and destroyed within them, thus failing to infect the host cell. 
E)  Yes, it IS a good strategy. If the microbe attaches to a critical receptor, the host cell will be forced to try to rid itself of the pathogen. One way it can do this is to phagocytose the pathogen, thereby taking it into its own nucleus, which benefits the pathogen.

Question 12

Finally, you use a diagram to illustrate to Jay how some pathogens avoid phagocytosis, which is part of the innate immune defense. You tell him that Salmonella is able to avoid phagocytosis by preventing formation of the phagolyososome. Which of the following is NOT a way for a pathogen to avoid phagocytosis?

Accepted Answer

A)  Some pathogens escape from the phagosome before it fuses with lysosomes. 
B)  Some pathogens survive the destructive environment within the phagolysosome. 
C)  Some pathogens avoid being recognized by phagocytes and thus avoid being engulfed by the cell. 
D)  Some pathogens kill phagocytes, often by using toxins to form pores in their membranes. 
E)  Some pathogens are serum-resistant, avoiding the killing effects of phagocyte complement proteins. 
A)  Some pathogens escape from the phagosome before it fuses with lysosomes. 
B)  Some pathogens survive the destructive environment within the phagolysosome. 
C)  Some pathogens avoid being recognized by phagocytes and thus avoid being engulfed by the cell. 
D)  Some pathogens kill phagocytes, often by using toxins to form pores in their membranes. 
E)  Some pathogens are serum-resistant, avoiding the killing effects of phagocyte complement proteins.

Question 13

Please select the CORRECT definition regarding interactions between hosts and microbes.

Accepted Answer

A)  Immunocompetent-having a weakness or defect in the innate or adaptive defenses. 
B)  Parasitism-relationship between two organisms in which one partner benefits and the other is unaffected. 
C)  Dysbiosis-an imbalance in the microbiome that may be caused by taking antimicrobial medications. 
D)  Secondary infection-infection in a previously healthy person, such as measles in a child who has not had measles before. 
E)  Fc receptors-molecule that binds the antigen-binding region of an antibody. 
A)  Immunocompetent-having a weakness or defect in the innate or adaptive defenses. 
B)  Parasitism-relationship between two organisms in which one partner benefits and the other is unaffected. 
C)  Dysbiosis-an imbalance in the microbiome that may be caused by taking antimicrobial medications. 
D)  Secondary infection-infection in a previously healthy person, such as measles in a child who has not had measles before. 
E)  Fc receptors-molecule that binds the antigen-binding region of an antibody.

Question 14

The microorganisms that are occasionally found in or on the body are called

Accepted Answer

A)  abnormal microbiota. 
B)  transient microbiota. 
C)  variant microbiota. 
D)  normal microbiota. 
E)  random biota. 
A)  abnormal microbiota. 
B)  transient microbiota. 
C)  variant microbiota. 
D)  normal microbiota. 
E)  random biota.

Question 15

The lack of susceptibility to diseases of other species in humans may be due to the

Accepted Answer

A)  lack of any cytokine production. 
B)  presence of endotoxins. 
C)  lack of any cytokine production AND secretion of exotoxins. 
D)  presence of endotoxins AND secretion of exotoxins. 
E)  lack of receptors that are recognized by adherence factors. 
A)  lack of any cytokine production. 
B)  presence of endotoxins. 
C)  lack of any cytokine production AND secretion of exotoxins. 
D)  presence of endotoxins AND secretion of exotoxins. 
E)  lack of receptors that are recognized by adherence factors.

Question 16

You explain to Jay that some pathogens induce non-phagocytic cells to engulf them. Gram-negative bacteria such as Salmonella often inject effector proteins that induce engulfment by host cells. In the case of Salmonella, specific proteins are delivered to intestinal epithelial cells via

Accepted Answer

A)  a type I secretion system. 
B)  a type II secretion system. 
C)  a type III secretion system. 
D)  a type IV secretion system. 
E)  a type I OR a type III secretion system. 
A)  a type I secretion system. 
B)  a type II secretion system. 
C)  a type III secretion system. 
D)  a type IV secretion system. 
E)  a type I OR a type III secretion system.

Question 17

The damage caused by parasites may be due to all of the following EXCEPT

Accepted Answer

A)  competition for nutrients. 
B)  the parasite's immune response. 
C)  the physical blocking of organs. 
D)  the direct digestion of host tissue. 
E)  the host's immune response. 
A)  competition for nutrients. 
B)  the parasite's immune response. 
C)  the physical blocking of organs. 
D)  the direct digestion of host tissue. 
E)  the host's immune response.

Question 18

Which of the following would be considered a sign of a disease?

Accepted Answer

A)  Severe headache 
B)  Throbbing pain 
C)  Intense nausea 
D)  Fever of 39°C 
E)  All of these are signs 
A)  Severe headache 
B)  Throbbing pain 
C)  Intense nausea 
D)  Fever of 39°C 
E)  All of these are signs

Question 19

You examine the baby thoroughly, telling the parents that you need to record all signs and symptoms for your report to the clinician who will also assess the baby. The parents tell you they know what symptoms are but they don't know what you mean by signs. You tell them that

Accepted Answer

A)  symptoms are objective and can be measured (such as fever) while signs are subjective and cannot be measured (such as pain). 
B)  signs are objective and can be measured (such as pain) while symptoms are subjective and cannot be measured (such as a rash). 
C)  symptoms are objective and can be measured (such as pain) while signs are subjective and cannot be measured (such as a rash). 
D)  signs are objective and can be measured (such as fever) while symptoms are subjective and cannot be measured (such as nausea). 
E)  signs and symptoms mean the same thing, and can be used interchangeably. 
A)  symptoms are objective and can be measured (such as fever) while signs are subjective and cannot be measured (such as pain). 
B)  signs are objective and can be measured (such as pain) while symptoms are subjective and cannot be measured (such as a rash). 
C)  symptoms are objective and can be measured (such as pain) while signs are subjective and cannot be measured (such as a rash). 
D)  signs are objective and can be measured (such as fever) while symptoms are subjective and cannot be measured (such as nausea). 
E)  signs and symptoms mean the same thing, and can be used interchangeably.

Question 20

What is the difference between a primary pathogen and an opportunistic pathogen?

Accepted Answer

A)  A primary pathogen is a microbe that is able to cause disease in an otherwise healthy individual, while an opportunistic pathogen is a microbe that causes disease only when introduced into an unusual location or into an immunocompromised host. 
B)  An opportunistic pathogen is a microbe that is able to cause disease in an otherwise healthy individual, while a primary pathogen is a microbe that causes disease only when introduced into an unusual location or into an immunocompromised host. 
C)  A primary pathogen is an environmental microbe that is able to cause disease in an otherwise healthy individual, while an opportunistic pathogen is always a member of the normal microbiota and causes disease only when introduced into an unusual location. 
D)  A primary pathogen is an environmental microbe that is able to cause disease in an otherwise healthy individual, while an opportunistic pathogen is always a member of the normal microbiota and only causes disease in an immunocompromised host. 
E)  A primary pathogen is a microbe that is able to cause disease in an otherwise healthy individual, while opportunistic pathogens are the microorganisms routinely found growing in and on the body of a healthy individual. 
A)  A primary pathogen is a microbe that is able to cause disease in an otherwise healthy individual, while an opportunistic pathogen is a microbe that causes disease only when introduced into an unusual location or into an immunocompromised host. 
B)  An opportunistic pathogen is a microbe that is able to cause disease in an otherwise healthy individual, while a primary pathogen is a microbe that causes disease only when introduced into an unusual location or into an immunocompromised host. 
C)  A primary pathogen is an environmental microbe that is able to cause disease in an otherwise healthy individual, while an opportunistic pathogen is always a member of the normal microbiota and causes disease only when introduced into an unusual location. 
D)  A primary pathogen is an environmental microbe that is able to cause disease in an otherwise healthy individual, while an opportunistic pathogen is always a member of the normal microbiota and only causes disease in an immunocompromised host. 
E)  A primary pathogen is a microbe that is able to cause disease in an otherwise healthy individual, while opportunistic pathogens are the microorganisms routinely found growing in and on the body of a healthy individual.

Exam 16: Host-Microbe Interactions

High concentrations of some bacteria are necessary for successful invasion because their virulence genes are only expressed at high population densities.

A human fetus has no resident microbial population.

People who carry and may spread pathogenic organisms without any apparent signs or symptoms of illness are called

Which of the following members of the normal microbiota inhibit the growth of Candida albicans?

The composition of the normal microbiota may be affected by

In two of Koch's postulates (#2 and #3), a pure culture of the organism is required. Which of the following would NOT be a possible consequence of using a contaminated culture?

The infectious dose of most pathogens is about equal.

Species of both Shigella and Streptococcus

The length of the incubation period depends on a variety of factors, including

An example of genetic variation used in pathogen survival may be

Is it a good strategy for a microbe to adhere to a receptor that plays a critical function for a host cell?

Please select the CORRECT definition regarding interactions between hosts and microbes.

The microorganisms that are occasionally found in or on the body are called

The lack of susceptibility to diseases of other species in humans may be due to the

You explain to Jay that some pathogens induce non-phagocytic cells to engulf them. Gram-negative bacteria such as Salmonella often inject effector proteins that induce engulfment by host cells. In the case of Salmonella, specific proteins are delivered to intestinal epithelial cells via

The damage caused by parasites may be due to all of the following EXCEPT

Which of the following would be considered a sign of a disease?

You examine the baby thoroughly, telling the parents that you need to record all signs and symptoms for your report to the clinician who will also assess the baby. The parents tell you they know what symptoms are but they don't know what you mean by signs. You tell them that

What is the difference between a primary pathogen and an opportunistic pathogen?

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

Identifying and Classifying Microorganisms

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

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

Filters