Question 1

What special adaptation(s) has/have Thermoplasma evolved to survive in hot acidic environments?

Accepted Answer

A)  Thermoplasma stabilize their cytoplasmic membrane by incorporation of tetraether lipoglycans in the cytoplasmic membrane. 
B)  Thermoplasma have a reinforced cell wall containing basic amino linkers in the peptidoglycan. 
C)  Thermoplasma excrete hydrogen ions and import hydroxyl ions. 
D)  Thermoplasma are highly motile to avoid destruction. 
A)  Thermoplasma stabilize their cytoplasmic membrane by incorporation of tetraether lipoglycans in the cytoplasmic membrane. 
B)  Thermoplasma have a reinforced cell wall containing basic amino linkers in the peptidoglycan. 
C)  Thermoplasma excrete hydrogen ions and import hydroxyl ions. 
D)  Thermoplasma are highly motile to avoid destruction.

Question 2

The light-stimulated proton pump of Halobacterium salinarum indirectly functions to pump sodium out of the cell by the activity of a Na⁺/H⁺ antiport system.

Accepted Answer

A) True 
 B)False

Question 3

The cytoplasmic membrane of Picrophilus is extremely acid impermeable at very low pH.

Accepted Answer

A) True 
 B)False

Question 4

Potassium cyclic 2,3-diphosphoglycerate (cDPG) is present at concentrations of 1M or more in the cytoplasm of many hyperthermophilic methanogens. The function of this compound is to

Accepted Answer

A)  prevent rRNA misfolding. 
B)  prevent chemical damage to DNA at high temperatures. 
C)  introduce supercoils into DNA. 
D)  activate hydrogen gas. 
A)  prevent rRNA misfolding. 
B)  prevent chemical damage to DNA at high temperatures. 
C)  introduce supercoils into DNA. 
D)  activate hydrogen gas.

Question 5

While many Archaea are bacilli or cocci, unusual morphologies such as square, flattened and irregular discs have also been identified in certain species.

Accepted Answer

A) True 
 B)False

Question 6

Some species, mostly classified as Euryarchaeota, have archaeal histones that may contribute to DNA stability as well as having other functions.

Accepted Answer

A) True 
 B)False

Question 7

Proteins known as ________ function to refold partially denatured proteins.

Accepted Answer

A)  histones 
B)  chaperonins 
C)  HU proteins 
D)  histones and chaperonins 
A)  histones 
B)  chaperonins 
C)  HU proteins 
D)  histones and chaperonins

Question 8

Most halobacteria are motile by means of lophotrichous archaella.

Accepted Answer

A) True 
 B)False

Question 9

Which genus within Archaea is capable of growth at the hottest temperature recorded of 122°C?

Accepted Answer

A)  Methanopyrus 
B)  Thermoproteus 
C)  Thermosphaera 
D)  Pyrococcus 
A)  Methanopyrus 
B)  Thermoproteus 
C)  Thermosphaera 
D)  Pyrococcus

Question 10

Hyperthermophilic Archaea generally have a lower GC ratio in their genomic DNA than in their ribosomal RNA.

Accepted Answer

A) True 
 B)False

Question 11

Extremely halophilic Archaea often form ________, probably in order to access ________.

Accepted Answer

A)  stalks / nutrients 
B)  intracellular inclusions / elemental sulfur 
C)  gas vesicles / oxygen 
D)  intracellular membranes / sunlight 
A)  stalks / nutrients 
B)  intracellular inclusions / elemental sulfur 
C)  gas vesicles / oxygen 
D)  intracellular membranes / sunlight

Question 12

Why does Archaeoglobus represent a metabolically transitional type of organism that bridges the energy-generating processes of H₂S production and methanogenesis?

Accepted Answer

Archaeoglobus is not generally thought o

Question 13

A chemoorganotroph growing optimally at 55°C and pH₂ in complex media would most likely be a member of the genus

Accepted Answer

A)  Methanocaldococcus. 
B)  Halobacterium. 
C)  Methanococcus. 
D)  Thermoplasma. 
A)  Methanocaldococcus. 
B)  Halobacterium. 
C)  Methanococcus. 
D)  Thermoplasma.

Question 14

Methanogenesis is coupled with proton motive force formation and ATP synthesis through the activity of ATPases.

Accepted Answer

A) True 
 B)False

Question 15

The most common electron donor used among hyperthermophilic Archaea is

Accepted Answer

A)  Fe⁺³ 
B)  H₂. 
C)  SO₄. 
D)  Sᵒ. 
A)  Fe⁺³ 
B)  H₂. 
C)  SO₄. 
D)  Sᵒ.

Question 16

Describe two mechanisms that Archaea use to avoid their DNA melting at temperatures above 100°C.

Accepted Answer

Answers will vary. One mechanism involve

Question 17

It is difficult to estimate when cyanobacteria appeared on Earth using the evidence from the oxidation state of the Earthʹs crust because

Accepted Answer

A)  several ancient anaerobic metabolisms require O₂. 
B)  there are multiple forms of anoxygenic photosynthesis. 
C)  there are multiple groups of oxygenic photosynthetic bacteria. 
D)  several ancient anaerobic metabolisms form Fe³⁺ without requiring O₂. 
A)  several ancient anaerobic metabolisms require O₂. 
B)  there are multiple forms of anoxygenic photosynthesis. 
C)  there are multiple groups of oxygenic photosynthetic bacteria. 
D)  several ancient anaerobic metabolisms form Fe³⁺ without requiring O₂.

Question 18

Hot sulfur-rich environments associated with terrestrial sulfur-rich springs are called

Accepted Answer

A)  acid-mine drainage. 
B)  hydrothermal vents. 
C)  solfataras. 
D)  terrestrial volcanoes. 
A)  acid-mine drainage. 
B)  hydrothermal vents. 
C)  solfataras. 
D)  terrestrial volcanoes.

Question 19

Which of the following bioenergetic processes CANNOT occur in hyperthermophiles?

Accepted Answer

A)  chemoorganotrophy 
B)  chemolithotrophy 
C)  photosynthesis 
D)  chemoorganotrophy and chemolithotrophy 
A)  chemoorganotrophy 
B)  chemolithotrophy 
C)  photosynthesis 
D)  chemoorganotrophy and chemolithotrophy

Question 20

Archaeal histones assist in maintaining the DNA in a double-stranded form at very high temperatures in species of Euryarchaeota.

Accepted Answer

A) True 
 B)False

Exam 17: Diversity of Archaea

What special adaptation(s) has/have Thermoplasma evolved to survive in hot acidic environments?

The light-stimulated proton pump of Halobacterium salinarum indirectly functions to pump sodium out of the cell by the activity of a Na⁺/H⁺ antiport system.

The cytoplasmic membrane of Picrophilus is extremely acid impermeable at very low pH.

Potassium cyclic 2,3-diphosphoglycerate (cDPG) is present at concentrations of 1M or more in the cytoplasm of many hyperthermophilic methanogens. The function of this compound is to

While many Archaea are bacilli or cocci, unusual morphologies such as square, flattened and irregular discs have also been identified in certain species.

Some species, mostly classified as Euryarchaeota, have archaeal histones that may contribute to DNA stability as well as having other functions.

Proteins known as ________ function to refold partially denatured proteins.

Most halobacteria are motile by means of lophotrichous archaella.

Which genus within Archaea is capable of growth at the hottest temperature recorded of 122°C?

Hyperthermophilic Archaea generally have a lower GC ratio in their genomic DNA than in their ribosomal RNA.

Extremely halophilic Archaea often form ________, probably in order to access ________.

Why does Archaeoglobus represent a metabolically transitional type of organism that bridges the energy-generating processes of H₂S production and methanogenesis?

A chemoorganotroph growing optimally at 55°C and pH₂ in complex media would most likely be a member of the genus

Methanogenesis is coupled with proton motive force formation and ATP synthesis through the activity of ATPases.

The most common electron donor used among hyperthermophilic Archaea is

Describe two mechanisms that Archaea use to avoid their DNA melting at temperatures above 100°C.

It is difficult to estimate when cyanobacteria appeared on Earth using the evidence from the oxidation state of the Earthʹs crust because

Hot sulfur-rich environments associated with terrestrial sulfur-rich springs are called

Which of the following bioenergetic processes CANNOT occur in hyperthermophiles?

Archaeal histones assist in maintaining the DNA in a double-stranded form at very high temperatures in species of Euryarchaeota.

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