Question 1

Some sulfur-oxidizing bacteria can simultaneously reduce nitrate,which enables them to grow anaerobically.

Accepted Answer

A) True 
 B)False  True

Question 2

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. B

Question 3

Chemolithotrophs that obtain electrons from donors such as sulfide use the same electron transport chains to obtain energy as chemoorganotrophs.

Accepted Answer

A) True 
 B)False  True

Question 4

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 convert the concentrated CO₂ 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 convert the concentrated CO₂ into biomass.

Question 5

Bacteria that are capable of oxidizing both iron and sulfur usually have a strong preference for sulfur oxidation because it yields more energy.

Accepted Answer

A) True 
 B)False

Question 6

Ferrous iron (Fe²⁺)oxidation generally occurs in environments with

Accepted Answer

A)  alkaline conditions. 
B)  high H⁺ concentrations. 
C)  high oxygen content. 
D)  little or no light present. 
A)  alkaline conditions. 
B)  high H⁺ concentrations. 
C)  high oxygen content. 
D)  little or no light present.

Question 7

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 c

Question 8

The foul-smelling putrescine byproduct suggests activity of

Accepted Answer

A)  amino acid fermentation by clostridia. 
B)  secondary fermentation. 
C)  sulfur-oxidizing bacteria. 
D)  syntrophic carbohydrate metabolism. 
A)  amino acid fermentation by clostridia. 
B)  secondary fermentation. 
C)  sulfur-oxidizing bacteria. 
D)  syntrophic carbohydrate metabolism.

Question 9

Glucose fermentation by Clostridium spp.produce ATP only when acetate and butyrate are produced.Why do these organisms produce acetone and butanol after strong initial activity of generating ATP with acetate and butyrate byproducts?

Accepted Answer

A)  Acetate and butyrate accumulation creates a deadly acidic environment, which acetone and butanol do not. 
B)  Acetate and butyrate are no longer needed for biosynthetic pathways. 
C)  Acetone and butanol serve as better sources for NAD(P)⁺ reduction. 
D)  Acetone and butanol production is favored for stability to store intracellular carbon sources for potential nutrient poor conditions. 
A)  Acetate and butyrate accumulation creates a deadly acidic environment, which acetone and butanol do not. 
B)  Acetate and butyrate are no longer needed for biosynthetic pathways. 
C)  Acetone and butanol serve as better sources for NAD(P)⁺ reduction. 
D)  Acetone and butanol production is favored for stability to store intracellular carbon sources for potential nutrient poor conditions.

Question 10

A bacterium that uses CO₂ as an electron source but CANNOT use it as a carbon source is considered a mixotroph.

Accepted Answer

A) True 
 B)False

Question 11

The light-harvesting pigments in Bacteria are classified as bacteriochlorophylls.

Accepted Answer

A) True 
 B)False

Question 12

Each chlorophyll and bacteriochlorophyll type is distinguished by its absorption spectrum.

Accepted Answer

A) True 
 B)False

Question 13

Anammox is an anaerobic process that generates energy from ________ and forms N₂.

Accepted Answer

A)  ammonia 
B)  ammonium 
C)  ammonia and nitrate 
D)  ammonia and nitrite 
A)  ammonia 
B)  ammonium 
C)  ammonia and nitrate 
D)  ammonia and nitrite

Question 14

Which of the following is NOT a potential reason anoxic methane-oxidizing Archaea have not also acquired the ability to reduce sulfate?

Accepted Answer

A)  An individual electron acceptor such as sulfate is not always present where methane is. 
B)  Minimizing the metabolic requirements of the archaeon's genome size provides flexibility to interact with other reducing bacteria, such as nitrate reducers. 
C)  The archaeon-bacterium relationship yields more energy from methane oxidation/sulfate reduction when performed together than separately. 
D)  The methane-oxidizing Archaea will not easily acquire this metabolic capability from the bacterial partner. 
A)  An individual electron acceptor such as sulfate is not always present where methane is. 
B)  Minimizing the metabolic requirements of the archaeon's genome size provides flexibility to interact with other reducing bacteria, such as nitrate reducers. 
C)  The archaeon-bacterium relationship yields more energy from methane oxidation/sulfate reduction when performed together than separately. 
D)  The methane-oxidizing Archaea will not easily acquire this metabolic capability from the bacterial partner.

Question 15

Due to a chemical equilibrium,a syntrophic relationship can be disrupted if the product from the first partner's metabolism is removed too quickly.

Accepted Answer

A) True 
 B)False

Question 16

Explain why the discovery of iron-oxidizing phototrophs has important implications for both understanding the evolution of photosynthesis and explaining the large deposits of ferric iron (Fe³⁺)found in ancient sediments on Earth.

Accepted Answer

The sediments containing Fe³⁺ predate th

Question 17

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 18

Because H₂ levels in oxic environments are transient,it is likely that aerobic hydrogen bacteria shift between chemoorganotrophy and chemolithotrophy depending on levels of organic compounds and hydrogen in their habitats.

Accepted Answer

A) True 
 B)False

Question 19

Iron-oxidizing bacteria grow better in alkaline environments where protons are less likely to abiotically convert Fe²⁺ into Fe³⁺.

Accepted Answer

A) True 
 B)False

Question 20

Plastocyanin is a

Accepted Answer

A)  membrane-bound sac found in certain bacteria. 
B)  photosynthetic pigment found in some bacteria. 
C)  copper-containing protein in photosystem II that donates electrons to photosystem I. 
D)  blue-green bacterium known for its unusual photoreactive complex. 
A)  membrane-bound sac found in certain bacteria. 
B)  photosynthetic pigment found in some bacteria. 
C)  copper-containing protein in photosystem II that donates electrons to photosystem I. 
D)  blue-green bacterium known for its unusual photoreactive complex.

Exam 13: Metabolic Diversity of Microorganisms

Some sulfur-oxidizing bacteria can simultaneously reduce nitrate,which enables them to grow anaerobically.

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

Chemolithotrophs that obtain electrons from donors such as sulfide use the same electron transport chains to obtain energy as chemoorganotrophs.

Identifying carboxysomes in a bacterium suggests it

Bacteria that are capable of oxidizing both iron and sulfur usually have a strong preference for sulfur oxidation because it yields more energy.

Ferrous iron (Fe²⁺)oxidation generally occurs in environments with

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

The foul-smelling putrescine byproduct suggests activity of

Glucose fermentation by Clostridium spp.produce ATP only when acetate and butyrate are produced.Why do these organisms produce acetone and butanol after strong initial activity of generating ATP with acetate and butyrate byproducts?

A bacterium that uses CO₂ as an electron source but CANNOT use it as a carbon source is considered a mixotroph.

The light-harvesting pigments in Bacteria are classified as bacteriochlorophylls.

Each chlorophyll and bacteriochlorophyll type is distinguished by its absorption spectrum.

Anammox is an anaerobic process that generates energy from ________ and forms N₂.

Which of the following is NOT a potential reason anoxic methane-oxidizing Archaea have not also acquired the ability to reduce sulfate?

Due to a chemical equilibrium,a syntrophic relationship can be disrupted if the product from the first partner's metabolism is removed too quickly.

Explain why the discovery of iron-oxidizing phototrophs has important implications for both understanding the evolution of photosynthesis and explaining the large deposits of ferric iron (Fe³⁺)found in ancient sediments on Earth.

The metabolic diversity of photosynthetic bacteria stems from different

Because H₂ levels in oxic environments are transient,it is likely that aerobic hydrogen bacteria shift between chemoorganotrophy and chemolithotrophy depending on levels of organic compounds and hydrogen in their habitats.

Iron-oxidizing bacteria grow better in alkaline environments where protons are less likely to abiotically convert Fe²⁺ into Fe³⁺.

Plastocyanin is a

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