Test Bank Answers Chapter.34 The Microbe-Human Ecosystem

Prescott's Microbiology, 11e (Willey)

Chapter 34 The Microbe-Human Ecosystem

1) From which of the following body sites would you expect to isolate Staphylococcus, Propionibacterium, Streptococcus, and Corynebacterium as the primary colonizing microbiota?

A) Skin 

B) Deep gum regions

C) Small intestine

D) Stomach

2) From which body region would you expect to isolate Clostridium, Bacteroides, Fusobacterium, and other anaerobic genera?

A) Large intestine

B) Skin

C) Nasopharynx

D) Stomach

3) If the predominating microbiota of a particular human body site included Lactobacillus, Gardnerella, and Bacteroides, it would not be unusual to isolate which of the following genera as well? 

A) Candida

B) Neisseria

C) Bacillus

D) Hemophilus

4) Microbes such as Lactobacillus acidophilus colonize the human vagina by fermenting          .

A) glycogen

B) glucose

C) lactose

D) sucrose

5) A species of bacterium associated with the oil glands of the skin belongs to the genus ________.

A) Staphylococcus

B) Pityrosporum

C) Propionibacterium

D) Pityrosporum

6) Which of the following would you not find in the nasopharynx?

A) Streptococcus pneumoniae

B) Neisseria meningitidis

C) Haemophilus influenzae

D) Branhamella catarrhalis

7) Which of the following would you expect to find in the tonsilar crypts?

A) Micrococcus

B) Staphylococcus

C) Streptococcus

D) Neisseria

8) Microbiota of the skin are most likely to be found ________.

A) where there is little moisture

B) where the pH of the skin secretions is below 4

C) in association with oil and sweat glands

D) All of the choices are correct.

9) Under normal circumstances, the microbiota of the skin is kept in check by ________.

A) a pH above 8

B) a slightly acidic pH

C) phagocytic activity

D) excessive moisture

10) The term that refers to those microbes found as symbionts in a short relationship of a nongrowing nature is ________.

11) A bacterial genus that is found in large numbers in the intestinal tract of breast-fed infants is ________.

A) Bacteroides

B) Bifidobacteria

C) Escherichia

D) Doderlein's bacillus

12) Which of the following areas of the human body is(are) not normally free of microorganisms?

A) Respiratory tract

B) Intestinal tract

C) Eyes

D) All of the choices are correct.

13) While the lungs are not sterile, they are protected from pathogens by ________.

A) the ciliated epithelial cells

B) lysozyme in mucus

C) phagocytic action of alveolar macrophages

D) All of the choices are correct.

14) Gram-positive bacteria such as Propionibacterium acnes limit the growth of Gram-negative bacteria and some fungi on the human skin by converting secreted ________ to compounds with antimicrobial activity.

A) lipids

B) organic acids

C) salts

D) urea

15) The lower respiratory tract has a normal microbiota.

16) The lower genitourinary tract is usually free of microorganisms.

17) The skin surface is a favorable environment for colonization of Gram-negative bacteria.

18) Many anaerobic Gram-negative bacteria are normally found in the duodenum.

19) The oral cavity of humans normally becomes colonized with microorganisms within hours after birth.

20) Although the intestinal microbiota for most people consists of the same types of organisms, the relative percentages of organisms varies significantly from person to person.

21) Recent research has demonstrated a correlation between the presence of certain types of Gram-positive bacteria in the human gut with obesity and type 2 diabetes. These findings best support which of the following statements?

A) Normal microbiota may significantly impact human health and disease. 

B) The presence of Gram-positive bacteria in the human gut causes obesity and type 2 diabetes.

C) Gram-positive bacteria compose the majority of normal microbiota in the human gut of people with obesity and type 2 diabetes.

D) Obesity and type 2 diabetes is caused by normal microbiota in the human gut.

22) A microbiologist studying the human microbiome is interested in how a particular bacterial species may impact water absorption in the large intestine. Which of the following models is appropriate for this investigation?

A) A germfree mouse raised in a sterile environment

B) A normal mouse colonized with enteric microbiota found in the human colon

C) A germfree mouse inoculated with human microbiota shortly after birth

D) A human volunteer who is a carrier of that particular bacterial species

23) A germfree mouse that is not born by cesarean section is not a suitable animal model for investigating the interaction between a host and one type of bacteria. 

24) Which of the following types of experimental evidence suggests that a particular organism thought to be part of the human microbiome is, in fact, just a laboratory contaminant?

A) Absence of ribosomal RNA evidence in a specific host location where the organism was believed to have colonized

B) Presence of ribosomal RNA evidence in a specific host location where the organism was believed to have colonized

C) Absence of ribosomal RNA evidence in a specific host location where the organism was not expected to have colonized

D) Presence of ribosomal RNA evidence in a specific host location where the organism was not expected to have colonized

25) Microorganisms in the human colon are more often being described as mutualistic with human hosts rather than commensalistic. Why has this change in the definition of a symbiotic relationship occurred?

A) As we learn more about the ecology of the human microbiome, we recognize our dependence on these organisms for immunity, vitamin production, and other essential processes.

B) As we learn more about the ecology of the human microbiome, we have learned that these organisms are dependent on the nutrients that we provide for their survival.

C) As we learn more about the makeup of the human digestive tract, we realize that some microorganisms are potentially pathogenic while others are not.

D) All of the choices are correct.

26) The average adult houses more microbial cells (1014) than human cells (average about 1013).

27) Microorganisms commonly associated with the human body are traditionally referred to as the ________.

A) normal microbial flora

B) normal microbes

C) normal microbiota

D) normal microbial flora or the normal microbiota

28) A ________ is any disease-producing microorganism.

29) Why were the advent of metagenomics, and the application of molecular techniques such as single-cell and next-generation sequencing, important for defining a microbial relationship?

A) Newer methods revealed that symbiotic relationships exist between a host and one to thousands or more microorganisms, challenging the former definition of a symbiotic relationship as one that occurs between a single microbe and its host.    

B) Newer methods revealed that symbiotic relationships exist between a host and only one microbe, challenging the former definition of a symbiotic relationship as one that occurs between thousands to trillions of microbes and its host.  

C) Microbiologists originally defined symbiotic relationships as those existing only between bacteria and animal hosts; the advent of newer methods broadened the definition of a host to include organisms other than animals.

D) Microbiologists originally defined symbiotic relationships as those that were parasitic, where the microbe harmed the host; the advent of newer methods broadened the definition of symbiosis to include mutualistism and commensalism.

30) The combination of all the genes present in the human genome and those present in the trillions of microbes living in and on adults is known as the human ________.

31) The microbiome represents all the genes present in the trillions of microbes living on and in adult humans.

32) The ________ is the collection of microorganisms (and their genes) that are normally present in and on an organism.

33) Metagenomics has helped us to understand that the composition of the microbiome may be connected to many aspects of human health.

34) Which of the following is attributed to the derivation of the word "microbiome" by Joshua Lederberg?

A) As holobionts, humans live symbiotically with billions of microbes.

B) Microbial inhabitants do not affect human physiology.

C) As humans evolve, the microbes that coexist with them remain genetically unchanged.

D) Human health is unrelated to the microbes that cohabit the human ecosystem.

35) The human microbiome ________.

A) evolves with humans over time

B) is the same for each person

C) is unrelated to an individual’s lifestyle or gender

D) remains unchanged throughout a lifetime

36) Holobionts  ________.

A) are a collection of species that make up an ecosystem         

B) comprise a variety of niches on and within the host organism           

C) exhibit unique symbiotic relationships that vary from host to host

D) evolve with the host species over time

E) All of the choices are correct.

37) The number of microbes that make up the human microbiome is approximately equal to the number of human somatic cells.

38) All of the following are true of holobionts except ________.

A) the microbial inhabitants of the host remain unchanged throughout the host’s lifetime

B) the development of the microbiome is a selective process             

C) factors such as body location and environment influence microbial cohabitation

D) the availability of oxygen and nutrients creates unique niches within the human host

39) The importance of E. coli and streptococci in the newborn is that ________.

A) they facilitate removal of available oxygen thereby promoting the growth of bifidobacteria       

B) they cause disease, strengthening the immune system               

C) they prevent the growth of other, more dangerous microbes

D) they protect the infant from disease if they are bottle-fed

40) What factors promote the colonization of bifidobacteria in the newborn?

A) Limited oxygen in the intestines, and breast-feeding               

B) Bottle-feeding and cesarean delivery               

C) Early transition to solid food

D) Withholding infant vaccinations

41) Organisms of the microbiome that are halophiles are predominantly found ________.

A) on the skin          

B) in the stomach             

C) in the large intestine

D) in the vaginal tract

42) Organisms of the microbiome that are acidophiles can be found ________.

A) in the stomach               

B) in the mouth               

C) in the large intestine

D) in the esophagus

43) The adult female genital tract has a pH between 4.4 and 4.6. This is due to ________.

A) fermentation of glycogen by resident Lactobacillus

B) fungi that secrete acids         

C) repeated use of vinegar-based products

D) acid-producing epithelial cells that line the mucus membrane

44) Which statement regarding the skin microbiome is correct?

A) Dry areas, such as the forearms and buttocks, host the greatest diversity of bacteria.

B) Sites rich in sebaceous glands have the greatest diversity of bacteria.

C) The dry sites of the skin exhibit a lack of microbial diversity compared to other sites.

D) The skin microbiome is uniform, regardless of localized pH, salt content or moisture.

45) The microbiota of the human large intestine ________.

A) varies at the level of the genus, rather than the phyla               

B) is diverse but uniform from person to person

C) is unaffected by variations in lifestyle choices

D) can be permanently altered by dietary changes

46) Defining the "functional core microbiome", rather than simply characterizing each microorganism, attempts to ________.

A) describe the holistic benefits provided to the host by the collective biota       

B) determine the genetic sequence all the organisms in the human microbiome         

C) enumerate the organisms in each specific niche

D) dispel the myth that the microbiome affects human behavio

47) The peptidoglycan cell wall and short-chain fatty acids released by bacteria induces C-lectin production in the host cell, which kills Gram-positive microbes. This is an example of ________.

A) indirect microbiome-pathogen resistance

B) direct microbiome-pathogen resistance

C) homeostasis

D) mucosal tolerance

48) When a Gram-positive bacteria produces bacteriocins that kill other Gram-positive bacteria while they themselves are unharmed, it is an example of a direct mechanism of colonization resistance.

49) Which of the following statements represents the influence the gut microbiota has on immune regulation and homeostasis?

A) The gut microbiota sends signals that influence the morphology and migration of tissue macrophages.

B) The gut microbiota releases metabolites that affect circulating myeloid cells, ensuring their appropriate maintenance and removal.

C) The gut microbiota sends signals that influence the appropriate development of myeloid cells in the bone marrow.

D) All of the choices are correct.

50) Rationalize the following statement: "Toddlers who are administered frequent rounds of antibiotic treatment will suffer an inefficient immune system."

A) Antibiotics will kill the microbiome as well as any pathogens, which affects immune function since the microbiota release chemicals that affect the maturation and homeostasis of innate leukocytes.

B) Antibiotics kill innate white blood cells as well as any pathogens.

C) Antibiotics suppress inflammation as well as killing pathogens and since inflammation is a mechanism of defense, the toddler will lack that important process.

D) Antibiotics will kill the microbiome instead of the pathogens, since they are more abundant, thereby preventing the process of colonization resistance.

51) Determine the connection between the gut microbiome and the central nervous system.

A) Imbalance in the gut microbiome upregulates the production of IL-17 a pro-inflammatory cytokine, which alters the function of neurons and microglia.

B) Bacteria can directly stimulate the neurons of the enteric nervous system that line the gut, sending a message to the brain via the vagus nerve.

C) Soluble microbial products impact the CNS by affecting the permeability of the blood-brain barrier.

D) All of the choices are correct.

52) Short-chain fatty acids such as butyrate, negatively impact the central nervous system by making the blood-brain barrier more permeable, allowing toxins and infectious agents to cross.

53) Which of the following statements is false regarding metabolic syndrome?

A) Metabolic syndrome develops when an individual cannot metabolize fats due to a genetic anomaly, resulting in obesity.

B) Metabolic syndrome involves the inability of the body to take up glucose from the bloodstream due to insulin resistance.

C) Insulin resistance can lead to type 2 diabetes and both conditions are associated with obesity, a hallmark of metabolic syndrome.

D) Metabolic syndrome and obesity are associated with chronic inflammation, which has a known link to diet-induced dysbiosis.

54) Check all of the following conditions that are associated with metabolic syndrome.

A) Large waist circumference

B) High blood pressure

C) High blood triglycerides

D) Type 1 diabetes

E) High fasting blood glucose

F) Low LDL levels

G) Low blood pressure

55) Metabolic endotoxemia refers to the diet-induced change in the microbiome leading to limited microbial diversity and dysbiosis, which allows LPS to pass through leaky colonocyte junctions, stimulating pro-inflammatory chemicals.

56) Which of the following statements regarding the relationship between diet and the gut microbiome is false?

A) A diet rich in red meat and high fat results in an overproduction of short-chain fatty acids.

B) A diet rich in fiber results in a microbiome population that produces short-chain fatty acids.

C) A diet rich in red meat promotes the production of trimethylamine in "meat-eating" microbes, which has been shown to promote atherosclerosis.

D) Microbes normally fed a vegetarian diet produce low levels of the atherosclerosis-promoting trimethylamine even when fed a diet high in red meat.

57) Microbial metabolism of L-carnitine produces trimethylamine, which travels to host liver cells where it is oxidized to trimentylamine N-oxide and has been shown to accelerate atherosclerosis.

58) Helicobacter pylori has been shown to cause cancer by ________.

A) increasing production of stomach acids, which erodes the stomach lining resulting in proliferation to overcome the loss of cells

B) producing a metalloprotease called Bft that stimulates the production of high levels of radical oxygen species by host cells, which in turn are mutagenic

C) producing CagA protein and injecting it into host cells, which leads to upregulation of genes that control cell proliferation, survival, migration, and blood vessel formation

D) All of the choices are correct.

59) Viruses are known to cause cancer in humans by altering the cell cycle and preventing DNA repair. Bacteria in the microbiome have also been shown to cause cancer, however they do by a different mechanism; once they infect a cell they take over the host cell machinery causing proliferation and tumor formation.

60) Probiotics are ________.

A) live microorganisms, which, when administered in adequate amounts, confer a health benefit to the host

B) foods or supplements that include both a substance that enhances colonization and live microorganisms

C) compounds added to the diet to enhance the colonization and positive health benefits of the microbiome

D) FDA-approved supplements to promote the colonization of live microorganisms and simultaneously prevent the growth of pathogens

61) The term "probiotics" refers to FDA-approved supplements that promote the colonization of live microorganisms and simultaneously prevent the growth of pathogens in the human gut.

62) One proposed way probiotics may be used in illness prevention is  ________.

A) the administration of a consortia of organisms to outcompete infection-causing antibiotic-resistant bacteria

B) tourists taking a probiotic preparation in anticipation of a trip to an area lacking U.S. standards of food and water treatment

C) outpatients are given a cocktail of organisms to reconstitute a depleted microbiome following aggressive treatment, which promotes colonization resistance

D) All of the choices are correct.

63) Probiotics have long been regulated and used in the prevention of illness in humans; now strategies are being explored to utilize probiotics in animals.