Deck 18: Bacterial Diversity

Question 1

All of the following are mechanisms that provide an anoxic environment for nitrogenase activity in cyanobacteria EXCEPT:

A) formation of heterocysts
B) formation of chlorosomes
C) temporal separation of photosynthesis and nitrogen fixation
D) formation of large aggregates of cells
E) symbiotic associations with plants

Answer 1

B

Question 2

Cyanobacteria are the only prokaryotes that use __________ to hydrolyze water with O₂-release.

A) photosystem I alone
B) bacteriochlorophyll
C) both photosystems I and II
D) plastocyanin
E) none of the above

Answer 2

C

Question 3

Which of the following species of Bacillus produces a biological insecticide?

A) B. subtilis
B) B. anthracis
C) B. thuringiensis
D) B. thermophilus
E) B. halodurans

Answer 3

C

Question 4

Which of the following is correct with respect to Streptococcus species?

A) They grow as chains, as a result of binary fission in one direction.
B) They are aerotolerant fermenters.
C) Some species cause tooth decay, as they ferment food residues and lower pH to 4.
D) All of the above.
E) None of the above.

Question 5

An ancient __________ is assumed to be in the same lineage as mitochondria.

A) Rhizobium
B) Mycoplasma
C) Clostridium
D) Rickettsia
E) cyanobacterium

Question 6

Bacteria in the genera __________ produce durable endospores that remain viable for millennia.

A) Carboxydothermus and Listeri
B) Lactobacillus and Streptococcus
C) Bacillus and Clostridium
D) all of the above
E) none of the above

Question 7

Which of the following is correct about lactic acid bacteria?

A) Most are obligate fermenters.
B) They are non-spore-forming bacteria.
C) They use substrate-level phosphorylation to generate ATP.
D) All of the above.
E) None of the above.

Question 8

Which of the following is NOT correct about the non-spore-forming Firmicutes?

A) This group includes lactic acid bacteria such as Lactococcus and Lactobacillus.
B) They include the mycoplasmas, which possess cell walls made of pseudopeptidoglycan.
C) Food spoilers such as Leuconostoc and Pediococcus belong to this group.
D) They may have evolved from endospore-forming bacteria.
E) Listeria species include enteric pathogens that contaminate cheese and sauerkraut.

Question 9

The __________ are the only known Firmicutes phototrophs that produce endospores.

A) actinomycetales
B) bacillales
C) clostridiales
D) heliobacteriaceae
E) none of the above

Question 10

Which of the following is NOT correctly matched?

A) Clostridium difficile-antibiotic resistance
B) Clostridium acetobutylicum-ferments to butanol and acetone
C) Clostridium botulinum-source of "botox"
D) Clostridium tetani-cases of sudden infant death syndrome
E) Clostridium botulinum-botulism

Question 11

A bacterial phylum is a group of organisms that share a common ancestor that diverged early from other bacteria, based on:

A) small-subunit (16S) rRNA sequences
B) the presence of certain plasmids
C) their genomic size
D) having 70S or 80S ribosomes
E) the presence or absence of a cell wall

Question 12

Which of the following is NOT an extremophile?

A) Bacillus alkalophilus
B) Bacillus thermophilus
C) Bacillus subtilis
D) Bacillus halodurans
E) none of the above

Question 13

Which of the following is NOT matched correctly?

A) Leuconostoc-food spoiler
B) Lactobacillus-endospores
C) Listeria-facultative anaerobe
D) Staphylococcus-salt tolerant
E) Streptococcus-scarlet fever

Question 14

Dehalobacter restrictus conducts anaerobic respiration by:

A) reducing aromatic rings of lignin-derived compounds
B) donating electrons to Fe³⁺, converting it to Fe²⁺ in mine ores
C) donating electrons to Cl atoms, effectively performing dechlorination
D) donating electrons to NO₃^-, converting via denitrification to NO₂^-
E) donating electrons to SO₄^2-, converting it to HS^-

Question 15

Bacteria are widely diverse in their cell structure, metabolism, and ecological adaptations, but share some major common traits. Which of the following statements is NOT true?

A) They share common features in central apparatus for gene expression and translation.
B) Bacterial gene expression mechanisms differ from those of the eukaryotes, which underlines the selective activity of many antibiotics.
C) Some archaeal cell walls are composed of pseudopeptidoglycan and thus may have different antibiotic sensitivity than bacteria.
D) Mycoplasmas lack cell walls and are thus not susceptible to antibiotics.
E) In bacteria, variant forms of peptidoglycan distinguish different species which thus may have different antibiotic sensitivity.

Question 16

Which of the following is matched correctly?

A) Mycoplasma-rod-shaped
B) Anabaena-akinetes
C) Clostridium-aerobe
D) Neisseria-wall-less
E) Rhizobium-gas vesicle

Question 17

Which of the following is NOT correct about microorganisms in the phylum Thermotogae?

A) They are among the extreme bacterial thermophiles.
B) Archaeal genes have been transferred horizontally to them.
C) They have fast doubling rates and high mutation rates.
D) They are bacteria with sheath-like outer structures.
E) They are aerobic heterotrophs.

Question 18

Among the mechanisms to avoid nitrogenase inhibition by oxygen, cyanobacteria:

A) produce organic acids; aerobic heterotrophs consume available oxygen
B) develop heterocysts, thick-walled cells specialized in fixing nitrogen
C) perform photosynthesis by day and nitrogen fixation at night
D) form cell aggregates, favoring nitrogen fixation in the anaerobic interior
E) all of the above

Question 19

Which of the following factors is NOT involved in initiation of spore formation in Firmicutes?

A) carbon starvation
B) light limitation
C) phosphate starvation
D) nitrogen starvation
E) low pH

Question 20

The following is correct about the genus Clostridium:

A) It displays a wide range of fermentation pathways.
B) Harmless Clostridium species grow in the colon of human infants shortly after birth.
C) It consists of anaerobic spore formers.
D) C. difficile grows in the intestine of patients in which enteric bacteria have been eliminated.
E) All of the above.

Question 21

Which of the following is NOT correct about the outer membrane of Gram-negative proteobacterial cell wall?

A) It has receptor proteins and porins.
B) In pathogens, lipopolysaccharide facilitates phagocytosis.
C) Lipopolysaccharide is toxic when released by dying cells.
D) It is a lipid bilayer membrane.
E) Lipopolysaccharide is absent in the cytoplasmic membrane.

Question 22

Which of the following is NOT correct with respect to the species of Frankia?

A) They belong to the phylum Actinobacteria.
B) They can live as endophytes in the roots of some vascular plants, where they fix nitrogen.
C) Some species can protect plants, such as wheat, from fungal infection.
D) Some species can grow as saprophytes on dead leaf litter.
E) This species has not been found to form spores.

Question 23

The following bacterial genera belong to the Enterobacteriaceae. In particular, __________ display swarming behavior prior to forming __________.

A) Escherichia; colonies
B) Proteus; biofilms
C) Pseudomonas; endospores
D) Caulbacter; stalks
E) Myxobacteria; fruiting bodies

Question 24

Which gammaproteobacterial genera include species that oxidize H₂S to S⁰?

A) Escherichia and Enterobacter
B) Chromatium and Beggiatoa
C) Klebsiella and Shigella
D) Proteus and Erwinia
E) none of the above

Question 25

Corynebacterium species have a particular type of cell division that can be described as:

A) "half-snapping"
B) the formation of reticulate bodies
C) the formation of a forespore and a mother cell
D) stalking
E) none of the above

Question 26

Which of the following is NOT correctly matched?

A) Mycobacterium smegmatis-commensal on human skin
B) Mycobacterium leprae-causes leprosy
C) Mycobacterium tuberculosis-causes tuberculosis
D) Mycobacterium leprae-grows in armadillos
E) Mycobacterium smegmatis-an important human pathogen

Question 27

Where do Chromatium cells store sulfur?

A) cytoplasmic granules
B) periplasmic granules
C) attached sulfur globules
D) in their immediate environment
E) cytoplasmic vacuoles

Question 28

How could Dehalobacter restrictus be used in bioremediation?

A) It respires by donating electrons to Cl atoms in tetrachloroethene, used in dry cleaning.
B) It is an anaerobe that quickly digests plastics in landfills.
C) It catabolizes aromatic compounds by reductive degradation.
D) It removes salt from salt marshes.
E) It is not applicable for use in bioremediation.

Question 29

Pseudomonas aeruginosa may form __________ in the lungs of cystic fibrosis patients.

A) sarcinae
B) filaments
C) biofilms
D) cysts
E) capsule

Question 30

In sewage-treatment systems, nitrifiers such as __________ are used to remove toxic ammonia.

A) Neisseria gonorrhoeae and N. meningitidis
B) Thiobacillus spp.
C) Nitrosomonas, Nitrosolobus, and Nitrosovibrio
D) all of the above
E) none of the above

Question 31

The cell wall of Mycobacterium tuberculosis contains:

A) mycolyl-arabinogalactan-peptidoglycan
B) mycolic acids
C) phenolic glycolipids
D) all of the above
E) none of the above

Question 32

Bdellovibrio species can be described as:

A) small, comma-shaped cells
B) having a single flagellum
C) parasites of larger proteobacteria
D) all of the above
E) none of the above

Question 33

The following phyla include bacteria with irregular cell structures EXCEPT:

A) Nitrospirae
B) Chlamydiae
C) Planctomycetes
D) Verrucomicrobia
E) Mycoplasma

Question 34

The Gram-negative outer membrane (OM):

A) lipids contain long protein polymer extensions
B) is packed with porins
C) does not contain receptor proteins
D) promotes phagocytosis
E) lipids do not have any toxic effects in humans

Question 35

Rhodopseudomonas palustris is a photoheterolithotroph; this means that:

A) it is capable of almost all types of metabolism, depending on environmental conditions
B) it supplements its heterotrophy with photosynthesis
C) it can use a mineral electron donor
D) all of the above
E) none of the above

Question 36

Which of the following is NOT correct about the sulfur lithotrophic genus Beggiatoa?

A) It is a Gram-negative gammaproteobacterial group.
B) It oxidizes H₂S to S⁰.
C) It stores S⁰ in cytoplasmic granules.
D) It stores polyhydroxybutyrate.
E) None of the above.

Question 37

Which of the following is NOT correct regarding rhizobia?

A) Rhizobium, Bradyrhizobium, and Synorhizobium are among the genera comprising rhizobia.
B) Rhizobia may live freely in soil, but they prefer to establish symbioses with specific legumes.
C) Rhizobia form nodules in the roots to favor anaerobiosis and consequently nitrogen fixation.
D) They provide the host with leghemoglobins, which help the plant hosts combat pathogens.
E) Each species colonizes a particular host range for infection.

Question 38

Which of the following is NOT correct with respect to the mycoplasmas?

A) They have lost their cell wall and the S-layer through reductive evolution.
B) Their cells maintain their shape through a type of cytoskeleton.
C) When cultured on agar, their colonies have a "fried-egg" shape.
D) They are parasites of all kinds of multicellular organisms.
E) They have some of the largest bacterial genomes.

Question 39

A type of telomeres is found in:

A) rickettsias and mitochondria
B) cyanobacteria and chloroplasts
C) Streptomyces
D) Planctomycetes
E) the phylum Deinococcus-Thermus

Question 40

Which of the following is NOT correct about myxobacteria?

A) Myxobacterial fruiting bodies are similar to those of the eukaryotic slime molds.
B) Under nutrient scarcity, their cells attract each other and form fruiting bodies.
C) They are aquatic and live as commensals on fish scales.
D) They lack flagella and move along surfaces using a form of motility called gliding.
E) With up to 12.6 Mbp, their genomes are exceptionally large.

Question 41

Which of the following have multipartite genomes?

A) Borrelia spp.
B) Escherichia spp.
C) Bacillus spp.
D) Chlamydia spp.
E) Mycobacterium spp.

Question 42

Which of the following statements is NOT correct regarding the life cycle of Chlamydia?

A) Elementary bodies are taken up by the host cells via endocytosis.
B) Reticulate bodies differentiate from elementary bodies outside the host cell.
C) A reticulate body may persist in the host cell for long periods.
D) Reticulate bodies replicate and develop into elementary bodies.
E) Elementary bodies are metabolically inert and contain condensed DNA, resembling spores.

Question 43

Why is it that the deep-branching thermophiles may appear to have diverged from other bacteria earlier than they actually did?

Question 44

The __________ lack cell walls and have a double membrane around the nucleoid; their tolerance for low concentrations of nutrients is called __________.

A) Verrucomicrobia; ectosymbiosis
B) Planctomycetes; oligotrophy
C) chlamydias; endosymbiosis
D) myxomycetes; oligotrophy
E) none of the above

Question 45

Which of the following is correct regarding mobility of spirochete cells?

A) They may have one or more polar flagella.
B) Flagella extend and fold back within the periplasmic space.
C) Flagella rotate on proton-driven motors.
D) All of the above.
E) None of the above.

Question 46

How do "purple sulfur bacteria" and "purple nonsulfur bacteria" differ in their metabolism? Are they really purple?

Question 47

The phylum Deinococcus-Thermus contains organisms that thrive in very different environments. Compare and contrast Deinococcus species and Thermus species. Why are these organisms assigned to the same phylum?

Question 48

Methylobacterium species are methylotrophs; this means that:

A) they can grow on both single-carbon and larger organic compounds
B) they exclusively feed on methane
C) they generate methane as a product of fermentation
D) they perform bacteriochlorophyll-based photosynthesis
E) they are classified as lithotrophs

Question 49

Discuss the chemical nature of mycolic acids and some of the traits they confer to organisms that possess them.

Question 50

Which of the following is correct regarding bacteria in the genus Nitrospira?

A) They are Gram-negative, true lithotrophs, or autotrophs.
B) Nitrospira spp. possess carboxysomes where they fix CO₂ or H₂CO.
C) Nitrospira spp. are found in aquatic environments, where they remove excess nitrite.
D) All of the above.
E) None of the above.

Question 51

Describe four mechanisms cyanobacteria use to provide an anoxic environment for the oxygen-sensitive, nitrogen-fixation enzyme nitrogenase.

Question 52

What is oligotrophy? Provide examples.

Question 53

In what habitats can Verrucomicrobia be found?

A) aquatic, low-salt environments
B) terrestrial environments
C) the gastrointestinal tract of mammals
D) ectosymbionts of protists
E) all of the above

Question 54

What bacterial groups use actin as a means to leave their host cells? What advantage does this type of cellular invasion provide to intracellular pathogens?

Question 55

What is photoheterotrophy? Provide two examples.

Question 56

Consider the cell wall of Mycobacterium species. What are the advantages and disadvantages of such a complex structure?

Question 57

Which of the following is correct about Verrucomicrobia?

A) They lack a cell wall.
B) They have a peptidoglycan cell wall.
C) They display tubulin-containing wart-like cytoskeleton projections.
D) A and B are correct.
E) B and C are correct.

Question 58

Which of the following is NOT correct regarding the genus Leptospirillum?

A) It belongs to the phylum Nitrospirae and includes acidophilic iron oxidizers.
B) Some Leptospirillum species use Fe²⁺ as electron donor and O₂ as electron acceptor.
C) Some species contribute to acid mine drainage in iron mines, where they form pink biofilms.
D) All of the above.
E) None of the above.

Question 59

You want to know what makes proteins stable in thermophilic bacteria. How would you explore the amino acids or motifs that are involved in conferring thermostability to proteins?

Question 60

Which genus within the spirochetes includes the causative agent of Lyme disease?

A) Treponema
B) Holandina
C) Leptospira
D) Borrelia
E) Spirochaeta

Question 61

Compare and contrast the double membrane found in planctomycetes versus that found in the eukaryotic nucleus.

Question 62

Describe the cell wall of the Verrucomicrobia. How could these organisms have acquired this trait?

Question 63

What is unique about the genome of Borrelia species?

Question 64

Describe the unique way in which spirochetes can be isolated from other environmental species. What makes this possible?

Question 65

How could nitrifiers be utilized in treatment of wastewater?

Question 66

Briefly describe the cellular structure of spirochetes and their motility system. Please describe one of the methods you could use to isolate spirochetes from nonspirochetes.

Question 67

How do Bacteroides fragilis and B. thetaiotaomicron contribute to 15% of human caloric intake? Are there other benefits provided by these microbes to human health? Are they potentially pathogenic?

Question 68

The epsilonproteobacterium Helicobacter pylori is the cause of gastritis and stomach ulcers. What mechanism allows it to survive the acidic conditions of the mammalian stomach?

Question 69

After reading the news of an E. coli threat in the community, your family and friends ask you, "Is E. coli a pathogen?" What would you answer?

Question 70

Describe the metabolic characteristics of Chlorobium species.