Question 1

The aerated upper layer of soil is likely to have ________ concentrations of H₂ for aerobic H₂-oxidizing Bacteria, so these bacteria likely ________.

Accepted Answer

A)  high / thrive in such conditions by not competing with chemoorganotrophs 
B)  high / generate important reducing equivalents as byproducts for other microorganisms in the soil 
C)  low / do not occur in such habitats 
D)  low / will need a chemoorganotrophic way to grow as well 
A)  high / thrive in such conditions by not competing with chemoorganotrophs 
B)  high / generate important reducing equivalents as byproducts for other microorganisms in the soil 
C)  low / do not occur in such habitats 
D)  low / will need a chemoorganotrophic way to grow as well D

Question 2

Explain why most iron-oxidizing bacteria are obligately acidophilic, and discuss some of the environments where these organisms are found.

Accepted Answer

Oxidation of iron at a low pH does not create high yields of energy. However, to compensate for the oxidation of iron, a reduction must also occur to balance the reaction. At a low pH, protons can be subsequently reduced. Bacteria with this metabolic capacity are prevalent in acid-polluted and coal-mining environments.

Question 3

Despite being called the reverse citric acid cycle, this pathway is currently identified as the most ancient and widespread autotrophic pathway.

Accepted Answer

A) True 
 B)False  FALSE

Question 4

In most cases, the final product of sulfur oxidation is

Accepted Answer

A)  hydrogen sulfide. 
B)  elemental sulfur. 
C)  sulfate. 
D)  thiosulfate. 
A)  hydrogen sulfide. 
B)  elemental sulfur. 
C)  sulfate. 
D)  thiosulfate.

Question 5

Bacteria that degrade aromatic compounds with reductions steps rather than oxygenase activity prior to ring fission are likely to be anaerobes.

Accepted Answer

A) True 
 B)False

Question 6

Phototrophic purple bacteria such as Rhodobacter species are capable of nitrogen fixation.

Accepted Answer

A) True 
 B)False

Question 7

The conversion of light into chemical energy is called photoautotrophy.

Accepted Answer

A) True 
 B)False

Question 8

A monooxygenase can always be distinguished from a dioxygenase by incorporating only one oxygen atom from O₂ into the substrate rather than both.

Accepted Answer

A) True 
 B)False

Question 9

The metabolic diversity of photosynthetic bacteria stems from different

Accepted Answer

A)  bacteriochlorophylls and pigments they contain. 
B)  chlorophylls they can have and organic compounds they can produce. 
C)  light-harvesting complexes, electron donors, and organic compounds they produce. 
D)  unrelated taxa capable of photosynthesis. 
A)  bacteriochlorophylls and pigments they contain. 
B)  chlorophylls they can have and organic compounds they can produce. 
C)  light-harvesting complexes, electron donors, and organic compounds they produce. 
D)  unrelated taxa capable of photosynthesis.

Question 10

Identifying carboxysomes in a bacterium suggests it

Accepted Answer

A)  contains the reverse citric acid cycle. 
B)  has a deficient Calvin cycle and accumulated CO₂. 
C)  is in a carboxylic acid rich environment and is storing excess quantities for potentially harsh conditions. 
D)  will use the Calvin cycle to convert the concentrated into biomass. 
A)  contains the reverse citric acid cycle. 
B)  has a deficient Calvin cycle and accumulated CO₂. 
C)  is in a carboxylic acid rich environment and is storing excess quantities for potentially harsh conditions. 
D)  will use the Calvin cycle to convert the concentrated into biomass.

Question 11

Carotenoids are hydrophobic accessory pigments and vary widely in the color they can absorb.

Accepted Answer

A) True 
 B)False

Question 12

Compare and contrast the prokaryotic and eukaryotic light-gathering machinery function and spatial organization. Why do various chlorophylls show different absorption spectra?

Accepted Answer

Both prokaryotes and eukaryotes use chlo

Question 13

What metabolic advantage do cells have in storing the elemental sulfur byproduct from sulfide oxidation?

Accepted Answer

A)  The cells avoid producing transport energy waste to secrete the sulfur. 
B)  The byproduct serves as an electron reserve for subsequent oxidation. 
C)  Sulfur decreases the intracellular acidification for non-acid-tolerant sulfide oxidizers. 
D)  The byproduct can be used for other biosynthetic pathways that use sulfur, such as Rieske Fe-S proteins. 
A)  The cells avoid producing transport energy waste to secrete the sulfur. 
B)  The byproduct serves as an electron reserve for subsequent oxidation. 
C)  Sulfur decreases the intracellular acidification for non-acid-tolerant sulfide oxidizers. 
D)  The byproduct can be used for other biosynthetic pathways that use sulfur, such as Rieske Fe-S proteins.

Question 14

Heterofermentation CANNOT be differentiated from homofermentation based on the compound fermented.

Accepted Answer

A) True 
 B)False

Question 15

Under what circumstances does oxygenic photophosphorylation use non-cyclic photophosphorylation and when does it use cyclic photophosphorylation? Also describe what occurs during each process.

Accepted Answer

Oxygenic photosynthesis generates ATP vi

Question 16

Regarding CO₂ fixation mechanisms in the autotrophic green sulfur bacteria,

Accepted Answer

A)  Chlorobium uses the reverse citric acid cycle, and Chloroflexus uses the hydroxypropionate pathway. 
B)  Chlorobium uses the hydroxypropionate pathway, and Chloroflexus uses the reverse citric acid cycle. 
C)  both Chlorobium and Chloroflexus use the reverse citric acid cycle. 
D)  both Chlorobium and Chloroflexus use the hydroxypropionate pathway. 
A)  Chlorobium uses the reverse citric acid cycle, and Chloroflexus uses the hydroxypropionate pathway. 
B)  Chlorobium uses the hydroxypropionate pathway, and Chloroflexus uses the reverse citric acid cycle. 
C)  both Chlorobium and Chloroflexus use the reverse citric acid cycle. 
D)  both Chlorobium and Chloroflexus use the hydroxypropionate pathway.

Question 17

A cell that lacks sulfite reductase but can still oxidize sulfur for energy could be identified by

Accepted Answer

A)  adenosine phosphosulfate reductase coupled with substrate-level phosphorylation. 
B)  electrons being transferred to cytochrome c prior to shuttling them into the electron transport chain. 
C)  identifying an alternative quinone, flavoprotein, or cytochrome. 
D)  quantifying the release of sulfate byproduct. 
A)  adenosine phosphosulfate reductase coupled with substrate-level phosphorylation. 
B)  electrons being transferred to cytochrome c prior to shuttling them into the electron transport chain. 
C)  identifying an alternative quinone, flavoprotein, or cytochrome. 
D)  quantifying the release of sulfate byproduct.

Question 18

The acetyl-CoA pathway is a primary route for carbon source utilization.

Accepted Answer

A) True 
 B)False

Question 19

Fermentation often produces CO₂, which can be used by ________ as an electron acceptor for energy.

Accepted Answer

A)  acetogens 
B)  methanotrophs 
C)  methanogens 
D)  acetogens and methanogens 
A)  acetogens 
B)  methanotrophs 
C)  methanogens 
D)  acetogens and methanogens

Question 20

What will happen to a cyanobacterium that has its photosystem II (PSII) blocked?

Accepted Answer

A)  Additional electron acceptors, such as NADP⁺, will be required to oxidize oxygen and overcome the lost PSII process. 
B)  Anoxygenic photosynthesis only using photosystem I (PSI) could occur by using cyclic photophosphorylation and an alternative electron donor such as H₂S. 
C)  It will die from being unable to obtain energy for photosynthesis. 
D)  Photons will generate excessive reactive oxygen species and the cyanobacterium will die as a consequence. 
A)  Additional electron acceptors, such as NADP⁺, will be required to oxidize oxygen and overcome the lost PSII process. 
B)  Anoxygenic photosynthesis only using photosystem I (PSI) could occur by using cyclic photophosphorylation and an alternative electron donor such as H₂S. 
C)  It will die from being unable to obtain energy for photosynthesis. 
D)  Photons will generate excessive reactive oxygen species and the cyanobacterium will die as a consequence.

Exam 14: Metabolic Diversity of Microorganisms

The aerated upper layer of soil is likely to have ________ concentrations of H₂ for aerobic H₂-oxidizing Bacteria, so these bacteria likely ________.

Explain why most iron-oxidizing bacteria are obligately acidophilic, and discuss some of the environments where these organisms are found.

Despite being called the reverse citric acid cycle, this pathway is currently identified as the most ancient and widespread autotrophic pathway.

In most cases, the final product of sulfur oxidation is

Bacteria that degrade aromatic compounds with reductions steps rather than oxygenase activity prior to ring fission are likely to be anaerobes.

Phototrophic purple bacteria such as Rhodobacter species are capable of nitrogen fixation.

The conversion of light into chemical energy is called photoautotrophy.

A monooxygenase can always be distinguished from a dioxygenase by incorporating only one oxygen atom from O₂ into the substrate rather than both.

The metabolic diversity of photosynthetic bacteria stems from different

Identifying carboxysomes in a bacterium suggests it

Carotenoids are hydrophobic accessory pigments and vary widely in the color they can absorb.

Compare and contrast the prokaryotic and eukaryotic light-gathering machinery function and spatial organization. Why do various chlorophylls show different absorption spectra?

What metabolic advantage do cells have in storing the elemental sulfur byproduct from sulfide oxidation?

Heterofermentation CANNOT be differentiated from homofermentation based on the compound fermented.

Under what circumstances does oxygenic photophosphorylation use non-cyclic photophosphorylation and when does it use cyclic photophosphorylation? Also describe what occurs during each process.

Regarding CO₂ fixation mechanisms in the autotrophic green sulfur bacteria,

A cell that lacks sulfite reductase but can still oxidize sulfur for energy could be identified by

The acetyl-CoA pathway is a primary route for carbon source utilization.

Fermentation often produces CO₂, which can be used by ________ as an electron acceptor for energy.

What will happen to a cyanobacterium that has its photosystem II (PSII) blocked?

The Microbial World

Microbial Cell Structure and Function

Microbial Metabolism

Molecular Information Flow and Protein Processing

Microbial Growth and Its Control

Microbial Regulatory Systems

Molecular Biology of Microbial Growth

Viruses and Their Replication

Microbial Systems Biology

Viral Genomics, Diversity, and Ecology

Genetics of Bacteria and Archaea

Biotechnology and Synthetic Biology

Microbial Evolution and Systematics

Functional Diversity of Microorganisms

Diversity of Bacteria

Diversity of Archaea

Diversity of Microbial Eukarya

Taking the Measure of Microbial Systems

Microbial Ecosystems

Nutrient Cycles

Microbiology of the Built Environment

Microbial Symbioses

Microbial Symbioses with Humans

Microbial Infection and Pathogenesis

Innate Immunity: Broadly Specific Host Defenses

Adaptive Immunity: Highly Specific Host Defenses

Clinical Microbiology and Immunology

Epidemiology

Person-to-Person Bacterial and Viral Diseases

Vectorborne and Soilborne Bacterial and Viral Diseases

Waterborne and Foodborne Bacterial and Viral Diseases

Eukaryotic Pathogens: Fungi, Protozoans, and Helminths

Filters

The aerated upper layer of soil is likely to have concentrations of H₂ for aerobic H₂-oxidizing Bacteria, so these bacteria likely .