Question 1

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

Accepted Answer

The corkscrew motion of the cell body during spirochete motility turns out to have a physical advantage in highly viscous environments, such as human mucous secretions or agar culture medium. Few nonspirochetes can swim through agar at standard culture concentrations (1.5% agar); thus, growth within agar provides a way to isolate anaerobic spirochetes from environmental sources. When an environmental sample is inoculated into agar, other bacteria grow and concentrate at the injection point, whereas spirochetes migrate outward in a "veil" through the agar.

Question 2

Which of the following is NOT correct regarding rhizobia?

Accepted Answer

A)  Rhizobium, Bradyrhizobium, and Synorhizobium are among the genera comprising rhizobia. 
B)  They may live freely in soil, but they prefer to establish symbioses with specific legumes. 
C)  They 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. 
A)  Rhizobium, Bradyrhizobium, and Synorhizobium are among the genera comprising rhizobia. 
B)  They may live freely in soil, but they prefer to establish symbioses with specific legumes. 
C)  They 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. D

Question 3

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

Accepted Answer

In the planctomycetes, a double membrane surrounds the entire nucleoid, analogous to the double membrane surrounding the eukaryotic nucleus-a remarkable example of independent analogous evolution between bacteria and the eukaryotes. The actual function of the nucleoid-surrounding membrane varies with different species; for example, in anammox planctomycetes, a single membrane enclosing the nucleoid contains the complexes conducting the anammox reaction.

Question 4

Which feature, indicated in the following figure, do Chlorobi share with Chloroflexi and Chloracidobacterium thermophilum?

Accepted Answer

A)  chlorosomes 
B)  thylakoids 
C)  halophily 
D)  endospores 
E)  hormogonia 
A)  chlorosomes 
B)  thylakoids 
C)  halophily 
D)  endospores 
E)  hormogonia

Question 5

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

Accepted Answer

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. 
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 6

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

Accepted Answer

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

Question 7

All of the following are mechanisms that provide an anoxic environment for nitrogen fixation in cyanobacteria EXCEPT

Accepted Answer

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

Question 8

Describe the metabolic characteristics of Chlorobium species.

Accepted Answer

Chlorobi are strict photolithotrophs, us

Question 9

Treponema azotonutricium is known for its symbiotic association with

Accepted Answer

A)  phototrophs in microbial mats. 
B)  corals. 
C)  fungi in lichens. 
D)  protists in the termite gut. 
E)  the mammal epithelium. 
A)  phototrophs in microbial mats. 
B)  corals. 
C)  fungi in lichens. 
D)  protists in the termite gut. 
E)  the mammal epithelium.

Question 10

Clades of microbes that are recently defined or characterized are referred to as

Accepted Answer

A)  hyperthermophiles. 
B)  archaea. 
C)  phyla. 
D)  deep branching. 
E)  emerging. 
A)  hyperthermophiles. 
B)  archaea. 
C)  phyla. 
D)  deep branching. 
E)  emerging.

Question 11

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

Accepted Answer

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

Question 12

In what environment does Savagella form filaments through the production of intracellular offspring?

Accepted Answer

A)  aquatic, high salinity environments 
B)  hydrothermal springs 
C)  surgical wounds 
D)  mammalian skin tissue 
E)  mammalian gut epithelium 
A)  aquatic, high salinity environments 
B)  hydrothermal springs 
C)  surgical wounds 
D)  mammalian skin tissue 
E)  mammalian gut epithelium

Question 13

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?

Accepted Answer

Listeria uses the host cell's actin to b

Question 14

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

Accepted Answer

A)  Verrucomicrobia; ectosymbiosis 
B)  Planctomycetes; oligotrophy 
C)  Chlamydiae; endosymbiosis 
D)  Cyanobacteria; oligotrophy 
E)  Firmicutes; piezophily 
A)  Verrucomicrobia; ectosymbiosis 
B)  Planctomycetes; oligotrophy 
C)  Chlamydiae; endosymbiosis 
D)  Cyanobacteria; oligotrophy 
E)  Firmicutes; piezophily

Question 15

Cyanobacteria contain subcellular structures called carboxysomes that are rich in the enzyme ________ that fixes CO₂.

Accepted Answer

A)  decarboxylase 
B)  oxidase 
C)  urease 
D)  cellulase 
E)  Rubisco 
A)  decarboxylase 
B)  oxidase 
C)  urease 
D)  cellulase 
E)  Rubisco

Question 16

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

Accepted Answer

Some cyanobacteria form specialized nitr

Question 17

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

Accepted Answer

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

Question 18

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?

Accepted Answer

Their main source of energy is fermentat

Question 19

The type of telomere pictured below is found in

Accepted Answer

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

Question 20

Bacteroidetes are important components of what ecosystem?

Accepted Answer

A)  Antarctic brine lakes 
B)  the termite gut 
C)  hydrothermal springs 
D)  the human gut 
E)  acid mines 
A)  Antarctic brine lakes 
B)  the termite gut 
C)  hydrothermal springs 
D)  the human gut 
E)  acid mines

Exam 18: Bacterial Diversity

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

Which of the following is NOT correct regarding rhizobia?

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

Which feature, indicated in the following figure, do Chlorobi share with Chloroflexi and Chloracidobacterium thermophilum?

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

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

All of the following are mechanisms that provide an anoxic environment for nitrogen fixation in cyanobacteria EXCEPT

Describe the metabolic characteristics of Chlorobium species.

Treponema azotonutricium is known for its symbiotic association with

Clades of microbes that are recently defined or characterized are referred to as

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

In what environment does Savagella form filaments through the production of intracellular offspring?

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?

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

Cyanobacteria contain subcellular structures called carboxysomes that are rich in the enzyme ________ that fixes CO₂.

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

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

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?

The type of telomere pictured below is found in

Bacteroidetes are important components of what ecosystem?

Microbial Life: Origin and Discovery

Observing the Microbial Cell

Cell Structure and Function

Bacterial Culture, Growth, and Development

Environmental Influences and Control of Microbial Growth

Viruses

Genomes and Chromosomes

Transcription, Translation, and Bioinformatics

Gene Transfer, Mutations, and Genome Evolution

Molecular Regulation

Viral Molecular Biology

Biotechniques and Synthetic Biology

Energetics and Catabolism

Electron Flow in Organotrophy, Lithotrophy, and Phototrophy

Biosynthesis

Food and Industrial Microbiology

Origins and Evolution

Archaeal Diversity

Eukaryotic Diversity

Microbial Ecology

Microbes in Global Elemental Cycles

Human Microbiota and Innate Immunity

The Adaptive Immune Response

Microbial Pathogenesis

Microbial Diseases

Antimicrobial Therapy

Clinical Microbiology and Epidemiology

Filters

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

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