MCB122 Symbioses2

1) Pathogenicity is the ability

A) of the host to inflict damage on the pathogen.

B) of the host to resist damage by the pathogen.

C) of the pathogen to inflict damage on the host.

D) None of these are correct.

C) of the pathogen to inflict damage on the host.

2) Which of the following is NOT a subunit of lipopolysaccharide (LPS)?

A) O-specific polysaccharide

B) lipid A

C) core polysaccharide

D) M protein

D) M protein

3) One microenvironment of the skin is an area where glands produce an oily substance called

A) mucus.

B) sebum.

C) fimbrae.

D) lipid A.

B) sebum.

4) Following antibiotic therapy, patients are often administered ________ to facilitate recolonizaton of normal flora.

A) fluoride

B) iron

C) probiotics

D) antivirals

C) probiotics

5) Decalcification of the tooth enamel due to the production of high concentrations of organic acids in the mouth is known as

A) degenerative plaque.

B) dental caries.

C) dental plaque.

D) microbial enamel decalcification.

D) microbial enamel decalcification.

6) The following bacterial species are all implicated in dental caries EXCEPT

A) Fusobacterium.

B) Borrelia.

C) Streptococcus.

D) Lactobacillus.

D) Lactobacillus.

7) Which of these microorganisms is MOST likely to be found in the human gut?

A) Helicobacter pylori

B) Streptococcus sobrinus

C) Streptococcus mutans

D) Roseobacter denitrificans

A) Helicobacter pylori

8) Normal flora in the duodenum are

A) similar to the microflora in the stomach.

B) dominated by aerobic organisms.

C) tolerant to alkaline environments.

D) tolerant to high salinity.

A) similar to the microflora in the stomach.

9) Which of the following are NOT found in the gastrointestinal tract of healthy humans?

A) Bacteroides

B) Clostridium

C) Escherichia coli

D) protists

D) protists

10) The following compounds are all produced by intestinal microflora EXCEPT

A) flatus.

B) vitamin C.

C) vitamin B12.

D) vitamin K.

B) vitamin C.

11) Staphylococcus aureus produces ________, leading to fibrin clots that protect them from attack by host cells.

A) collagenase

B) coagulase

C) lipase

D) amylase

B) coagulase

12) Only particles smaller than ________ µm in diameter reach the lungs.

A) 10

B) 20

C) 30

D) 40

A) 10

13) The vagina of adult female is

A) highly acidic.

B) highly alkaline.

C) weakly acidic.

D) weakly alkaline.

C) weakly acidic.

14) Which of the following hemolysins is a phospholipase?

A) lecithinase

B) Streptolysin-O

C) Staphylococcal -toxin

D) leukocidin

A) lecithinase

15) Streptocoocus pyogens utilizes M protein and ________ to form microfibrils that facilitate attachment to host cells.

A) lipoteichoic acid

B) mucus

C) plaque

D) None of the answers are correct.

A) lipoteichoic acid

16) Influenza virus targets

A) respiratory epithelium.

B) gastrointestinal cells.

C) oral cavity cells.

D) throat epithelium.

A) respiratory epithelium.

17) A polymer coat consisting of a dense, well-defined polymer layer surrounding a cell is called a

A) capsule.

B) glycocalyx.

C) lipopolysaccharide.

D) slime mold.

A) capsule.

18) Capsules are particularly important for

A) making bacteria more vulnerable to host defense mechanisms.

B) making bacteria less pathogenic.

C) protecting bacteria from host defense mechanisms.

D) allowing bacteria to become more phagocytic.

C) protecting bacteria from host defense mechanisms.

19) The decrease or loss of virulence of a pathogen is referred to as

A) aging.

B) attenuation.

C) disinfectivity.

D) lethal dose.

B) attenuation.

20) Attenuation occurs in a laboratory, because

A) nonvirulent or weakly virulent mutants grow faster in vitro in laboratory media.

B) pathogens lose virulence with age.

C) patients are generally treated with drugs that induce attenuation.

D) None of the answers are correct.

A) nonvirulent or weakly virulent mutants grow faster in vitro in laboratory media.

21) Which disease CANNOT be prevented via the use of a vaccine generated from an attenuated pathogen?

A) malaria

B) measles

C) mumps

D) rubella

A) malaria

22) Which of the following is NOT important for the adherence of bacteria to other bacteria as well as to host tissue?

A) adherence polymers

B) capsule

C) glycocalyx

D) slime layer

A) adherence polymers

23) Which of the following is an important factor in the development of dental caries?

A) high salt diet

B) high sugar diet

C) high acid diet

D) low salt diet

B) high sugar diet

24) The spread of pathogens through the blood and lymph systems that results in a bloodborne systemic infection is called

A) bacteremia.

B) cancer.

C) pathogenesis.

D) septicemia.

D) septicemia.

25) Which genus produces hyaluronidase?

A) Mycobacteria

B) Streptococcus

C) Shigella

D) Procholorococcus

D) Procholorococcus

26) Which of the following is more likely to cause urinary tract infections?

A) fimbriated strains of Escherichia coli

B) non-fimbriated strains of Escherichia coli

C) both fimbriated and non-fimbriated strains of Escherichia coli

D) None of the answers are correct.

A) fimbriated strains of Escherichia coli

27) Pathogenic strains of Escherichia coli usually express

A) capsules.

B) colonization factor antigens (CFA).

C) plaques.

D) slime layers.

B) colonization factor antigens (CFA).

28) Which of the following does NOT affect pathogen growth?

A) availability of microbial nutrients

B) pH

C) temperature

D) doubling time

D) doubling time

29) Siderophores from some pathogens remove iron from the host protein(s)

A) lactoferrin.

B) transferrin.

C) both lactoferrin and transferrin.

D) cytochromes.

C) both lactoferrin and transferrin.

30) Cytolytic toxins

A) are extracellular proteins.

B) cause cell lysis and death.

C) damage host cytoplasmic membrane.

D) are extracellular proteins that cause cell lysis and death by damaging the host cytoplasmic membrane.

D) are extracellular proteins that cause cell lysis and death by damaging the host cytoplasmic membrane.

31) Normal flora ________ colonization of pathogenic organisms.

A) promote

B) prevent

C) maintain

D) accelerate

B) prevent

32) The collective term for the organisms living on or in the human body is

A) normal microbial flora.

B) fomite flora.

C) transient microbial flora.

D) pathogenic flora.

A) normal microbial flora.

33) ________ in saliva cleaves glycosidic linkages in peptidoglycan present in bacterial cell walls, weakening the wall and causing cell lysis.

A) Mucus

B) Lysozyme

C) Fibrin

D) Lipid A

B) Lysozyme

34) Which of the following is a way to prevent attenuation and maintain virulence in a bacterium?

A) laboratory subculture

B) animal passage

C) polymerase chain reaction (PCR)

D) antibiotic therapy

B) animal passage

35) The human gastrointestinal tract includes all of the following EXCEPT the

A) small intestine.

B) stomach.

C) large intestine.

D) epiglottis.

D) epiglottis.

36) A(n) ________ is a damage or injury to a host organism that impairs its function.

A) trauma

B) infection

C) disease

D) transmission

C) disease

37) Virulence is the relative ability of a ________ to cause disease.

A) pathogen

B) commensal

C) virus

D) bacterium

A) pathogen

38) Which of the following is the dominate genera of skin microflora?

A) Bacteriodes

B) Firmicutes

C) Actinobacteria

D) Proteobacteria

C) Actinobacteria

39) Which of the following environmental and host factors influence the composition of resident microflora on the skin?

A) age

B) personal hygiene

C) weather

D) age, personal hygiene, and weather

D) age, personal hygiene, and weather

40) Extensive growth of the streptococci in a thick bacterial layer on acidic glycoproteins on the teeth is called

A) dental plaque.

B) dental caries.

C) dental biofilm.

D) periodontitis.

A) dental plaque.

41) Which of the following pathogens does NOT require capsules or a slime layer for attachment?

A) Vibrio cholera

B) Streptococcus pneumonia

C) Bacillus anthracis

D) All of these pathogens require capsules or slime layers for attachment.

A) Vibrio cholera

42) Which of the following is a major growth-limiting micronutrient that influences microbial growth?

A) iron

B) transferrin

C) lactoferrin

D) sugar

A) iron

43) The dose of an antigen that kills 50% of animals in a test group and is used to estimate the virulence of a pathogen is known as

A) Antigen dose50.

B) Virulence-50.

C) LD50 (lethal dose50).

D) Death rate-50.

C) LD50 (lethal dose50).

44) The process by which microorganisms cause diseases is known as

A) pathogenesis.

B) virulence.

C) LD50 (lethal dose50).

D) infection.

A) pathogenesis.

45) The macromolecules responsible for bacterial adherence that are NOT covalently attached to bacteria are collectively called

A) lipid A.

B) biofilms.

C) capsules.

D) glycocalyx.

D) glycocalyx.

46) A loose network of polymers extending outward from a cell is called a(n)

A) slime layer.

B) lipid A.

C) capsule.

D) adhesion.

A) slime layer.

47) The process by which white blood cells ingest and kill bacteria is called

A) exocytosis.

B) transcription.

C) phagocytosis.

D) translation.

C) phagocytosis.

48) The condition that results when some organisms are shed in the bloodstream and distributed to distant parts of the body during bacterial growth in tissues is called

A) septicemia.

B) bacteremia.

C) uremia.

D) erythemia.

B) bacteremia.

49) ________ are toxic proteins released from the pathogen as it grows.

A) Endotoxins

B) Exotoxins

C) Macrotoxins

D) Microtoxins

B) Exotoxins

50) Which of the following is a category of exotoxin?

A) cytolytic toxin

B) lipophilic toxin

C) α-toxin

D) β-toxin

A) cytolytic toxin

51) ________ are microbial infections acquired by hospital patients with noninfectious diseases because they are compromised hosts.

A) Healthcare-associated infections

B) Immunocompromised infections

C) Pathogenic infections

D) Virulent infections

A) Healthcare-associated infections

1) ALL microorganisms that live in the human body are harmful.

False

2) Bacteria found in the mouth in the first years of life are well-adapted to biofilm formation.

False

3) An opportunistic pathogen causes disease ONLY in the presence of normal host resistance.

False

4) Normal microflora are usually found in the blood, lymph, and nervous systems of the body.

False

5) Virulence refers to the ability of an organism to cause disease.

False

6) Streptococcus mutans can produce dextran when sucrose is present in the absence of the enzyme dextransucrase.

False

7) Pathogen virulence NEVER changes throughout a host's life.

False

8) Cholera begins following a bite from a mosquito.

False

9) Protists are NOT normally found in the gastrointestinal tract of healthy individuals.

True

10) Bacteria make up about one-third the weight of fecal matter.

True

11) Malassezia spp. are the MOST common fungi present on the skin of humans.

True

12) The upper respiratory tract usually has a considerable amount of resident microflora in a healthy adult.

False

13) Vaginal acidity in the adult female is due to acid production by Lactobacillus acidophilus.

True

14) R plasmids help prevent the spread of virulence factors.

False

15) Invasion is the ability of a pathogen to enter into host cells or tissues, spread, and cause disease.

True

16) The toxic lipopolysaccharides produced by MOST gram-negative bacteria are called exotoxins.

False

17) Endotoxins are released in large amounts only when cells lyse.

True

18) The Limulus amebocyte lysate assay is used to detect endotoxin in clinical samples such as serum or cerebrospinal fluid.

True

19) Gram-positive bacteria produce endotoxins.

False

20) Hormones that are produced under stress boost normal immune responses and play a role in stress-mediated disease resistance.

False

21) The number of Vibrio cholera cells necessary to produce cholera in an exposed individual is drastically reduced if the individual is malnourished.

True

22) Clostridium botulinum are endospore-forming bacteria normally found in the soil.

True

23) Animals that lack CXCR4 and CCR5 proteins are immune to HIV infection.

True

24) Diphtheria toxin inactivates elongation factor 2 by catalyzing the attachment of adenosine diphosphate ribose from NAD+.

True

25) Clostridium botulinum cannot produce toxins in improperly preserved foods.

False