Deck 16: Host-Microbe Interactions

Question 1

A disease-causing microorganism or virus is referred to as a(n)

A)avirulent infection.
B)colony.
C)commensal.
D)pathogen.

Answer 1

pathogen.

Question 2

Attributes of an organism that promote pathogenicity are called

A)disease factors.
B)colonization factors.
C)mutualistic.
D)virulence factors.

Answer 2

virulence factors.

Question 3

A relationship in which one partner benefits and the other is harmed is termed

A)commensalism.
B)parasitism.
C)independence.
D)mutualism.

Answer 3

parasitism.

Question 4

The series of steps used to connect an organism to a disease are known as

A)Pasteur's postulates.
B)Lister's aseptics.
C)Linnaeus taxonomics.
D)Koch's postulates.

Question 5

Newborn babies acquire microbiota by

A)passing through the birth canal.
B)breastfeeding.
C)contact with mother's skin.
D)environment.
E)All of the above are a source of microbiota.

Question 6

Opportunists or opportunistic pathogens

A)are usually saprophytes.
B)take advantage of special circumstances.
C)are usually mutualistic.
D)always cause disease.

Question 7

The number of organisms necessary to insure infection is termed the

A)infectious dose.
B)fatal number.
C)minimum lethal dose.
D)pathogenic number.

Question 8

The interaction of all organisms within a biological community with their environment is called a(n)

A)group.
B)cluster.
C)ecosystem.
D)network.

Question 9

Which of the following is true about the role normal microbiota plays in maintaining host health?

A)They provide a surface that is incompatible for attachment of an invader.
B)They establish competition for nutrients and vitamins.
C)They produce antimicrobial substances.
D)They stimulate the immune system.
E)All of the choices are true.

Question 10

The composition of the normal microbiota may be affected by

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

Question 11

The "hygiene hypothesis" proposes that

A)lack of exposure to microbes can promote development of allergies.
B)cleanliness truly is next to godliness.
C)hand washing is the best preventative measure against infection.
D)the immune system develops best in a clean environment.

Question 12

The connection between a particular organism and a specific disease was first made by

A)Jenner.
B)Pasteur.
C)Koch.
D)Leeuwenhoek.

Question 13

The microorganisms that are regularly found in or on the body,yet do no apparent harm are called

A)abnormal microbiota.
B)transient microbiota.
C)variant microbiota.
D)normal microbiota.

Question 14

Organisms that are found together and interact on a more or less permanent basis are in a relationship termed

A)mutualism.
B)parasitism.
C)symbiosis.
D)transient microbiota.

Question 15

The suffix -emia means in the

A)body.
B)lymph.
C)interstitial tissue.
D)blood.

Question 16

The infectious dose

A)is the same for all microorganisms.
B)may be 10-100 cells for Salmonella.
C)is expressed as ID50.
D)is defined as the number of microbes necessary to ensure infection.
E)is expressed as ID50 AND is defined as the number of microbes necessary to ensure infection.

Question 17

Growth of a parasitic organism in or on the host is referred to as

A)colonization.
B)infection.
C)pathogenism.
D)mutualism.

Question 18

A relationship in which one partner benefits and the other is unaffected is termed

A)commensalism.
B)parasitism.
C)independence.
D)mutualism.

Question 19

The symbiotic relationship wherein both partners benefit is termed

A)commensalism.
B)parasitism.
C)independence.
D)mutualism.

Question 20

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

A)abnormal microbiota.
B)transient microbiota.
C)variant microbiota.
D)normal microbiota.

Question 21

Which of the following may be considered virulence factor(s)?

A)Edhesins
B)Capsules
C)Endotoxins
D)Proteases
E)All of the choices are correct.

Question 22

If a disease affects only a human and not an animal,then it would be difficult to fulfill Koch's postulate number

A)1.
B)2.
C)3.
D)4.

Question 23

People who carry and may spread pathogenic organisms without any overt symptoms of illness are called

A)primary infections.
B)secondary infections.
C)mutualists.
D)carriers.

Question 24

Bacteria may survive phagocytosis by

A)preventing fusion of the lysosome with the phagosome.
B)lysing the phagosome.
C)producing comet tails.
D)preventing fusion of two phagosomes.
E)preventing fusion of the lysosome with the phagosome AND lysing the phagosome.

Question 25

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

A)Headache
B)Pain
C)Nausea
D)Fever of 39 ^$\circ$ C

Question 26

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

A)secretion of exotoxins.
B)presence of endotoxins.
C)action of IL-2.
D)lack of receptors that are recognized by adherence factors.

Question 27

Typically,adhesins

A)are found on pili.
B)help bacteria attach to host cells.
C)are proteins.
D)are found on host cells.
E)are found on pili,help bacteria attach to host cells,AND are proteins.

Question 28

Species of both Shigella and Streptococcus

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

Question 29

Which of the following does S.pneumoniae use to survive in the host?

A)Plasmids
B)Pili
C)Flagella
D)Capsules

Question 30

Which of the following factors is not considered important for the establishment of an infection?

A)Adherence
B)Dose
C)Toxicity
D)Virulence factors

Question 31

A more modern equivalent to Koch's Postulates is termed

A)Pasteur's Systematics.
B)Hoch's Postulates.
C)Atomic Theory.
D)Protein Theory.
E)Molecular Postulates.

Question 32

An example of genetic variation used in pathogen survival may be

A)production of a comet's tail.
B)protease production.
C)inhibition of MHC Class I antigen production.
D)changing the pilus type.
E)production of a comet's tail AND protease production.

Question 33

The spread of toxin via circulation is called

A)septicemia.
B)bacteremia.
C)sepsis.
D)toxemia.

Question 34

The first step in the establishment of infection is that the organism must

A)invade host tissues.
B)attach to host cells.
C)evade phagocytes.
D)produce toxins.

Question 35

Colonization of the body is inhibited by

A)the shedding of skin cells.
B)the movement of mucus by cilia.
C)peristalsis.
D)the flushing action of the urinary tract.
E)All of the choices are correct.

Question 36

Adhesins are

A)involved in the first step of the infectious process.
B)often found at the tip of pili.
C)found in flagella.
D)endotoxins.
E)involved in the first step of the infectious process AND often found at the tip of pili.

Question 37

The process by which infectious agents are ingested by host cells is termed

A)exocytosis.
B)pinocytosis.
C)endocytosis.
D)phagosome fusion.

Question 38

Bacteria that resist killing by complement proteins are termed

A)carriers.
B)serum resistant.
C)balanced pathogens.
D)mutualistic.
E)carriers AND serum resistant.

Question 39

Virulent pathogens are

A)more likely to cause disease.
B)more likely to cause severe disease.
C)unable to cause disease.
D)more likely to be opportunists.

Question 40

C5a peptidase

A)is a virulence factor.
B)synthesizes C5a.
C)is produced by the host cell in response to infection.
D)is a molecule promoting chemotaxis.
E)is a virulence factor AND is a molecule promoting chemotaxis.

Question 41

A human fetus has no resident microbial population.

Question 42

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

Question 43

Infection always leads to disease.

Question 44

Which is true about superantigens?

A)They are a type of exotoxin.
B)They bind to MHC class II antigen on T cells.
C)They enhance specific antibody production.
D)They are processed intracellularly.
E)They are a type of exotoxin AND they bind to MHC class II antigen on T cells.

Question 45

Only Gram-positive bacteria produce exotoxins.

Question 46

The normal microbiota provides protection against potentially harmful organisms and stimulates the immune system.Why would the immune responses to members of the normal microbiota cross-react with pathogens?

A)Because one person's normal microbiota is another person's pathogen-when we pick up "normal" microbes from a different person,they will always cause infection within us.
B)Because pathogens are oftentimes more virulent strains of our own normal microbial microbiota,so they will "look" roughly the same to our immune system (and be acted upon by our immune responses).
C)Because the normal microbiota keeps the adaptive immune responses tuned up,active,and ready to respond to broad,general categories of microbes (i.e.,Gram-positive vs.Gram-negative microbes,viruses,etc.).
D)Because the immune system is a "use it or lose it" system.If it isn't used on a regular basis,we completely lose the ability to respond to pathogens.The normal microbiota keeps the system going so that it can be ready to respond to such pathogens when we're exposed to them.

Question 47

During incubation and convalescence a person may still spread infectious organisms.

Question 48

A strong attachment of a microorganism to a host cell automatically leads to disease.

Question 49

Which of the following is/are true about endotoxins?

A)Lipid A is the toxic portion of the molecule.
B)The toxic effects depend on the bacteria from which it came.
C)The lipid A is immunogenic.
D)They are proteins.
E)The toxic effects depend on the bacteria from which it came AND they are proteins.

Question 50

Which of the following is NOT a likely reason why diseases caused by opportunists are becoming more frequent in the U.S.population?

A)HIV individuals (with impaired immune systems)survive longer due to more effective therapies-but this allows them a longer period of time to be infected by opportunists.
B)Individuals in the United States are living longer than ever before-but they're living with a number of chronic health issues that can impair the immune system.This leads to a greater likelihood of opportunistic infections.
C)Cancer treatments have improved significantly in the last 30 years-but they often suppress the immune system.This leads to a greater likelihood of opportunistic infections in such individuals.
D)Travel into and out of the United States has increased significantly.This has the potential to bring in many new pathogens that can cause new infections,even in otherwise healthy and immunocompetent individuals.

Question 51

The damage caused by parasites may be due to

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

Question 52

An infectious disease is an infection that impairs the normal state of health.

Question 53

The most successful parasites are the ones that live in harmony with their hosts.

Question 54

The chemical nature of exotoxins is that of a

A)protein.
B)carbohydrate.
C)lipid.
D)lipopolysaccharide.

Question 55

Which is/are true of viruses?

A)They may suppress the production of MHC Class I protein.
B)They may produce an MHC Class I mimic protein.
C)They may prevent cell suicide.
D)They may bind to MHC class II antigens.
E)They may suppress the production of MHC Class I protein,they may produce an MHC Class I mimic protein,AND they may prevent cell suicide.

Question 56

The infectious dose of most pathogens is about equal.

Question 57

Disease(s)in which the causative agent becomes latent is/are

A)cold sores.
B)genital herpes.
C)shingles.
D)All of the choices are correct.

Question 58

Obligate intracellular parasites may be grown in special synthetic media.

Question 59

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?

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)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.
D)Even though there's a contaminating microbe present,so long as the original suspect microbe is also present,the disease should still manifest in test animals.It should also still be recoverable from test animals following infection.As such,there's really no consequence to using a contaminated culture.

Question 60

The chemical nature of endotoxins is that of a

A)protein.
B)nucleic acid.
C)lipid.
D)lipopolysaccharide.

Question 61

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

A)It ISN'T a good strategy-host cells could shift to a backup receptor and shut down production of the main receptor,preventing infection.
B)If it's a receptor the cell MUST use,it doesn't have a backup system in place to switch to-so,even though it makes it susceptible to infection,it HAS to put that target out there.This benefits the microbe.
C)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)It ISN'T a good strategy-by binding to receptors,microbes will be phagocytosed by cells and destroyed within them.

Question 62

A number of viruses often include a similar set of symptoms when they cause an infectious disease state (fever,headache,fatigue,runny nose).Why would they all cause the same symptoms if they're different viruses?

A)They all possess the same basic virulence genes and molecules,so they all trigger the same responses.
B)The symptoms are associated with the immune system's response,NOT the molecules from the pathogens themselves.Our responses against viruses are fairly similar,regardless of virus type,so the symptoms are similar.
C)Most viruses infect the upper respiratory tract-this leads to the common set of symptoms listed above.Only a few viruses infect areas away from this region.
D)Viruses specifically infect mainly epithelial membranes.As such,the virally induced reaction is similar in different areas of the body due to the same basic cell types (epithelial cells)being infected in each area.

Question 63

Home-canned foods should be boiled before consumption to prevent botulism.Considering that this treatment does NOT destroy endospores,why would it be helpful in preventing the disease?

A)Because it would destroy the vegetative cells,and only the vegetative cells cause the disease.
B)Because it would at least weaken the endospores,making them more susceptible to elimination by our immune system.
C)Because the heat would denature the botulism exotoxin and inactivate it.The exotoxin is what leads to the disease symptoms,so this would make the food safer.
D)Because the heat would denature the botulism endotoxin and inactivate it.The endotoxin is what leads to the disease symptoms,so this would make the food safer.