Deck 32: Microbial Interactions

Question 1

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

A)Streptococcus pneumoniae
B)Neisseria meningitidis
C)Haemophilus influenzae
D)Branhamella catarrhalis

Answer 1

D

Question 2

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

Answer 2

A

Question 3

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

A)Micrococcus
B)Staphylococcus
C)Streptococcus
D)Neisseria

Answer 3

A

Question 4

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

Question 5

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.

Question 6

Human sweat has antimicrobial activity due to

A)production of an antimicrobial peptide called cathelicidins.
B)competition with normal sweat gland flora.
C)production of low molecular weight compounds that maintain an alkaline pH.
D)production of low molecular weight compounds that chelate free iron.

Question 7

The lungs are protected from microorganisms by

A)the ciliated epithelial cells.
B)lysozyme in mucus.
C)phagocytic action of alveolar macrophages.
D)All of the choices are correct.

Question 8

The lower genitourinary tract is usually free of microorganisms.

Question 9

____________ arises when different microbes within a population or community try to acquire the same resource.

A)Amensalism
B)Competition
C)Disruption
D)Syntropism

Question 10

A species of bacterium associated with the oil glands of the skin belongs to the genus

A)Staphylococcus.
B)Pityrosporum.
C)Propionibacterium.
D)Pityrosporum.

Question 11

The lower respiratory tract has a normal microbiota.

Question 12

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

Question 13

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

Question 14

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

Question 15

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

A)glycogen
B)glucose
C)lactose
D)sucrose

Question 16

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.

Question 17

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.

Question 18

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

Question 19

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

Question 20

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.

Question 21

The average adult carries 10 times more microbial cells (10¹⁴)than human cells (average about 10¹³).

Question 22

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.

Question 23

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.

Question 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

Question 25

Biofilm formation by Pseudomonas bacteria on the surface of a natural loofa sponge kept in the shower is an example of which type of relationship?

A)Commensalism
B)Mutualism
C)Parasitism
D)Predation

Question 26

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

Question 27

When members of the normal microbiota of the human body become pathogenic and produce disease under certain circumstances,they are referred to as ______________ pathogens.

A)partial
B)conditional
C)occasional
D)opportunistic

Question 28

The relationship between Trichonympha protozoa and its termite host,and Xenorhabdus bacteria and its nematode host,are both obligatory relationships.

Question 29

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.

Question 30

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.

Question 31

Insects frequently contain bacteria in their cytoplasm,and these bacteria form a mutualistic association with their host.

Question 32

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.

Question 33

How are termite-related protists and aphid-related proteobacteria similar?

A)Both are mutualists with their respective hosts.
B)Both are parasites to their respective hosts.
C)Both are types of endosymbiotic bacteria.
D)Both are protozoans that live within insect hosts.

Question 34

Pseudonocardia is an organism that is hosted by

A)wood-eating insects.
B)marine invertebrates.
C)ants that cultivate fungal gardens.
D)people with severe acne.

Question 35

A researcher proposes that the relationship between a particular bacterial species that produces a fat-soluble vitamin is mutualistic with its insect host.Which of the following procedures would best test the researcher's hypothesis?

A)Determine which antibiotic kills the bacteria without harming the host,then administer this antibiotic to the insect and compare its growth with and without the vitamin
B)Determine which insecticide kills the insect without harming the bacterial host,then compare vitamin production by the bacteria from insects treated with the insecticide to those from untreated insects
C)Design a method to isolate the bacteria from the insect,then mutate the bacteria in the region of DNA that controls vitamin production and compare growth of the mutant and wild-type bacteria on minimal media
D)Extract the DNA from the bacteria and from the insect,then use reverse-transcriptase PCR and primers specific to the gene that controls vitamin synthesis to compare transcription of RNA in both organisms

Question 36

Several cases of an emerging infectious disease are reported in workers at a research station that borders a tropical rainforest region.The pathogen is identified as a species of bacteria carried by nematodes that infect mosquitos,and disease transmission occurs in a human host following a mosquito bite.Which organisms should be targeted in the treatment of infected patients?

A)Mosquito,nematode,and bacteria
B)Mosquito and nematode
C)Nematode and bacteria
D)Mosquito and bacteria

Question 37

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.

Question 38

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.

Question 39

Which of the following processes is not one that is common to all symbionts?

A)Predation
B)Colonization
C)Reproduction
D)Persistence

Question 40

A _________ is any disease-producing microorganism.

Question 41

Which of the following is not part of the lichen association?

A)Ascomycetes
B)Green algae
C)Brown algae
D)Cyanobacteria

Question 42

The reason coral reefs are among the most productive and successful ecosystems is due to

A)the coral-dinoflagellate mutualistic relationship.
B)the lichen mutualistic relationship.
C)commensalisms.
D)All of the choices are correct.

Question 43

When two different microbes are engaged in a cooperative relationship,they do as well when living separately as they do when living together.

Question 44

In the host-parasite relationship,it is advantageous for the parasite to disable and kill its host as quickly as possible.

Question 45

The loss of genetic information no longer needed for an intracellular existence by an obligate parasite is called genomic _____________ .

Question 46

The specialized structure in a tube worm in which endosymbiotic,chemolithotrophic bacteria live is called a(n)__________.

Question 47

Which of the following is not a category of symbiosis?

A)Mutualism
B)Communalism
C)Commensalism
D)Parasitism

Question 48

The term ____________ is used to describe a mutually beneficial association in which the growth of an organism is dependent on one or more growth factors,nutrients,or substrates provided by another organism in the same vicinity.

Question 49

Any microorganism that spends a portion of its life associated with another organism of a different species is engaged in

A)symbiosis.
B)synergy.
C)parasitism.
D)commensalism.

Question 50

In commensalism

A)the host and commensal can be separated and remain viable.
B)the commensal is metabolically dependent on the host.
C)the host provides some factor that the commensal cannot get otherwise.
D)the host and commensal cannot be separated and remain viable and the commensal is metabolically dependent on the host.

Question 51

In mutualism

A)the mutualist is dependent on the host.
B)a reciprocal benefit accrues to both partners.
C)the partners will not survive separately in many cases.
D)All of the choices are correct.

Question 52

In the rumen,the carbohydrate fermentation end products include

A)acetate.
B)carbon dioxide.
C)methane.
D)All of the choices are correct.

Question 53

In the rumen,food is quickly attacked by cellulase

A)enzymes produced by the ruminant.
B)enzymes produced by microbes.
C)enzymes produced by both the ruminant and the microbe.
D)archeons.

Question 54

__________ enzymes catalyze the hydrolysis of beta (1-4)linkages between successive D-glucose residues of cellulose.

Question 55

A close physical relationship between two different species that may or may not be beneficial is called __________.

Question 56

A relationship in which one organism is found on the surface of another is referred to as a(n)___________.

Question 57

____________ is a beneficial relationship similar to mutualism,in which the relationship is not obligatory.

Question 58

In a lichen,the fungal partner

A)protects the alga from excess light intensities.
B)provides water and minerals to the alga.
C)provides a substratum within which the alga grows.
D)All of the choices are correct.

Question 59

An example of microbial ___________ is the ability of Vampirococcus to attach to the outer membrane of its prey and then secrete degradative enzymes that result in the release of the prey's cytoplasmic contents.

Question 60

Coral bleaching where the photosynthetic endosymbiont is lost or becomes non-functional can be caused by temperature increases as small as 2^oC.

Question 61

The ectosymbionts of ruminant animals are useful to their hosts in which of the following ways?

A)They digest the cellulose of plant cell walls.
B)They produce most of the vitamins needed by the ruminant.
C)They convert glucose to organic acids.
D)All of the choices are correct.

Question 62

Dinoflagellates that exist endosymbiotically within a variety of marine invertebrates are called

A)endoflagellates.
B)parasites.
C)endotrophic.
D)zooxanthellae.

Question 63

Mussels and sponges sometimes contain methanotrophs as intracellular symbionts because the methanotrophs

A)remove otherwise toxic levels of methane from the environment.
B)convert methane to carbohydrate for use by the host.
C)allow the partnership to use hydrogen sulfide as a source of electrons.
D)All of the choices are correct.

Question 64

The rickettsial parasite Wolbachia pipientis can

A)sometimes alter the sex of an infected wasp.
B)confer toxicity to the sting of an infected wasp.
C)enhance the life-span of an infected wasp.
D)None of the choices are correct.

Question 65

A physical relationship where an organism hosts more than one symbiont is known as a

A)clade.
B)consortium.
C)partnership.
D)cojoining.

Question 66

The filamentous bacteria that grow on the dorsal surface of certain polychaete worms

A)fend off potential predators with toxins.
B)carry out photosythesis.
C)may provide the worm with protection from toxic metals.
D)All of the choices are correct.

Question 67

________________ is a predator that bores a hole through the outer membrane of its gram-negative bacterial prey and then reproduces in the periplasm.

A)Vampirococcus
B)Bdellovibrio
C)Daptobacter
D)Syntrophobacter

Question 68

Methanogens are always engaged in relationships with other microbes because methane production requires

A)removal of oxygen from the environment by another microbe.
B)energy provided by another microbe.
C)interspecies hydrogen transfer.
D)None of the choices are correct.

Question 69

In lichens,the fungi send projections of their hyphae across the algal cell wall in order to obtain nutrients from the photosynthetic partner.These projections are called

A)mycelia.
B)hyphal extensions.
C)haustoria.
D)lichenthropes.

Question 70

Riftia tube worms make a unique kind of hemoglobin to

A)transport oxygen.
B)transport hydrogen sulfide.
C)to assist in the transport of carbon dioxide.
D)All of the choices are correct.

Question 71

Buchnera aphidicola provides ___________ to its aphid host that are essential to the survival of the insect.

A)carbohydrates
B)vitamins
C)amino acids
D)cellulases

Question 72

A unidirectional process where a specific compound released by one organism has a negative effect on another organism is called

A)predation.
B)commensalism.
C)negative cooperation.
D)amensalism.

Question 73

When Nitrobacter utilizes nitrite produced from ammonia by Nitrosomonas to obtain energy by converting the nitrite to nitrate,the relationship between the two organisms is

A)commensal.
B)amensal.
C)mutual.
D)parasitic.