Question 1

In most salt lakes, which microbial group is the major oxygenic phototroph?

Accepted Answer

A)  cyanobacteria 
B)  Dunaliella, a eukaryotic alga 
C)  halophilic Archaea 
D)  purple nonsulfur bacteria 
A)  cyanobacteria 
B)  Dunaliella, a eukaryotic alga 
C)  halophilic Archaea 
D)  purple nonsulfur bacteria

Question 2

Thermoplasma contains an extremely small genome complexed with a highly basic DNA-binding protein.

Accepted Answer

A) True 
 B)False

Question 3

Most of the Archaea are phenotypically quite similar.

Accepted Answer

A) True 
 B)False

Question 4

Thus far, only Archaea have been found in the salt lakes, while Bacteria and Eukarya are noticeably absent.

Accepted Answer

A) True 
 B)False

Question 5

Some Archaea are chemoorganotrophs and use organic compounds as electron donors for energy metabolism.

Accepted Answer

A) True 
 B)False

Question 6

What makes the lifestyle and genome of Nanoarchaeum equitans unique?

Accepted Answer

N. equitans is the only identified intra

Question 7

Halophilic Archaea are the only inhabitants of highly saline environments.

Accepted Answer

A) True 
 B)False

Question 8

Cellular integrity and cell wall stabilization of the Halobacterium are aided by

Accepted Answer

A)  potassium ions. 
B)  chloride ions. 
C)  magnesium ions. 
D)  sodium ions. 
A)  potassium ions. 
B)  chloride ions. 
C)  magnesium ions. 
D)  sodium ions.

Question 9

In chemolithotrophic Archaea, H₂ is a common electron donor.

Accepted Answer

A) True 
 B)False

Question 10

Nitrifying Thaumarchaeota can outcompete nitrifying bacteria in acidic environments because Thaumarchaeota

Accepted Answer

A)  are well-adapted to high salinity and extreme UV irradiation. 
B)  are well-adapted to temperature extremes. 
C)  are well-adapted to very low NH₃ concentrations. 
D)  have very resistant specialized cells that survive long periods of dehydration and nutrient starvation. 
A)  are well-adapted to high salinity and extreme UV irradiation. 
B)  are well-adapted to temperature extremes. 
C)  are well-adapted to very low NH₃ concentrations. 
D)  have very resistant specialized cells that survive long periods of dehydration and nutrient starvation.

Question 11

Methanogens

Accepted Answer

A)  produce methane as a part of their energy metabolism. 
B)  utilize methane as an energy source. 
C)  process and store methane to detoxify it. 
D)  produce, utilize, and detoxify methane. 
A)  produce methane as a part of their energy metabolism. 
B)  utilize methane as an energy source. 
C)  process and store methane to detoxify it. 
D)  produce, utilize, and detoxify methane.

Question 12

Although the domain Archaea contains many acidophilic organisms, there are still many others within the domain that grow well in environments with a neutral pH.

Accepted Answer

A) True 
 B)False

Question 13

The small ribosomal rRNA gene sequences of hyperthermophilic Archaea and Bacteria have relatively high GC content, which

Accepted Answer

A)  increased stability at high temperatures because GC pairs are joined by 3 hydrogen bonds. 
B)  decreased stability at high temperatures because GC pairs are joined by 2 hydrogen bonds. 
C)  increased mutation rates at high temperatures compared with other rRNA. 
D)  considerable variation in their GC content, making this unhelpful as a distinguishing feature between them and non-hyperthermophilic Archaea and Bacteria. 
A)  increased stability at high temperatures because GC pairs are joined by 3 hydrogen bonds. 
B)  decreased stability at high temperatures because GC pairs are joined by 2 hydrogen bonds. 
C)  increased mutation rates at high temperatures compared with other rRNA. 
D)  considerable variation in their GC content, making this unhelpful as a distinguishing feature between them and non-hyperthermophilic Archaea and Bacteria.

Question 14

Thermoplasma are facultative aerobes, growing either aerobically or anaerobically by sulfur respiration.

Accepted Answer

A) True 
 B)False

Question 15

Many hyperthermophiles are chemolithoautotrophs.

Accepted Answer

A) True 
 B)False

Question 16

Most haloarchaea use which of the following for electron donors?

Accepted Answer

A)  amino and organic acids 
B)  carbohydrates 
C)  lipids 
D)  nucleic acids 
A)  amino and organic acids 
B)  carbohydrates 
C)  lipids 
D)  nucleic acids

Question 17

The ribosomes of Halobacterium require high ________ levels for stability and activity.

Accepted Answer

A)  KCl 
B)  NaCl 
C)  NaSO₄ 
D)  acidic amino acid 
A)  KCl 
B)  NaCl 
C)  NaSO₄ 
D)  acidic amino acid

Question 18

Many archaeal hyperthermophiles are ________; however, Staphylothermus is a chemoorganotroph.

Accepted Answer

A)  chemolithotrophs 
B)  mixotrophs 
C)  parasites 
D)  photoheterotrophs 
A)  chemolithotrophs 
B)  mixotrophs 
C)  parasites 
D)  photoheterotrophs

Question 19

One unusual feature of Pyrococcus is that

Accepted Answer

A)  it incorporates carbon dioxide via the acetyl-CoA pathway. 
B)  it is very motile due to a tuft of polar archaealla. 
C)  it incorporates carbon dioxide via the reverse citric acid cycle. 
D)  it is a thermophilic aerobic chemoorganotroph that uses elemental sulfur. 
A)  it incorporates carbon dioxide via the acetyl-CoA pathway. 
B)  it is very motile due to a tuft of polar archaealla. 
C)  it incorporates carbon dioxide via the reverse citric acid cycle. 
D)  it is a thermophilic aerobic chemoorganotroph that uses elemental sulfur.

Question 20

Replacing sodium with potassium can satisfy the requirement for sodium in the halobacteria.

Accepted Answer

A) True 
 B)False

Exam 17: Diversity of Archaea

In most salt lakes, which microbial group is the major oxygenic phototroph?

Thermoplasma contains an extremely small genome complexed with a highly basic DNA-binding protein.

Most of the Archaea are phenotypically quite similar.

Thus far, only Archaea have been found in the salt lakes, while Bacteria and Eukarya are noticeably absent.

Some Archaea are chemoorganotrophs and use organic compounds as electron donors for energy metabolism.

What makes the lifestyle and genome of Nanoarchaeum equitans unique?

Halophilic Archaea are the only inhabitants of highly saline environments.

Cellular integrity and cell wall stabilization of the Halobacterium are aided by

In chemolithotrophic Archaea, H₂ is a common electron donor.

Nitrifying Thaumarchaeota can outcompete nitrifying bacteria in acidic environments because Thaumarchaeota

Methanogens

Although the domain Archaea contains many acidophilic organisms, there are still many others within the domain that grow well in environments with a neutral pH.

The small ribosomal rRNA gene sequences of hyperthermophilic Archaea and Bacteria have relatively high GC content, which

Thermoplasma are facultative aerobes, growing either aerobically or anaerobically by sulfur respiration.

Many hyperthermophiles are chemolithoautotrophs.

Most haloarchaea use which of the following for electron donors?

The ribosomes of Halobacterium require high ________ levels for stability and activity.

Many archaeal hyperthermophiles are ________; however, Staphylothermus is a chemoorganotroph.

One unusual feature of Pyrococcus is that

Replacing sodium with potassium can satisfy the requirement for sodium in the halobacteria.

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