Question 1

Most halobacteria are motile by means of lophotrichous flagella.

Accepted Answer

A) True 
 B)False

Question 2

The cytoplasmic membrane of Thermoplasma contains a lipopolysaccharide-like material called lipoglycan which

Accepted Answer

A)  behaves like peptidoglycan and creates a strong cell wall. 
B)  forms a monolayer that stabilizes the cytoplasmic membrane. 
C)  contains ether linkages. 
D)  contains ether linkages and forms a monolayer that stabilizes the cytoplasmic membrane. 
A)  behaves like peptidoglycan and creates a strong cell wall. 
B)  forms a monolayer that stabilizes the cytoplasmic membrane. 
C)  contains ether linkages. 
D)  contains ether linkages and forms a monolayer that stabilizes the cytoplasmic membrane.

Question 3

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 4

With few exceptions,hyperthermophilic crenarchaeotes are obligate aerobes.

Accepted Answer

A) True 
 B)False

Question 5

Though the known diversity of acetotrophic methanogens is low,they are ecologically significant in nature.

Accepted Answer

A) True 
 B)False

Question 6

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 7

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

Accepted Answer

A) True 
 B)False

Question 8

Approximately ________ of the Methanocaldococcus jannaschii genes have no counterparts in known genes from other sequenced organisms.

Accepted Answer

A)  10% 
B)  25% 
C)  40% 
D)  70% 
A)  10% 
B)  25% 
C)  40% 
D)  70%

Question 9

Explain why the presence of many Archaea has been confirmed only by community sampling of rRNA genes and not by culture in the laboratory.How has metagenomics helped to solve this problem?

Accepted Answer

Due to the extreme environmental conditi

Question 10

Hyperthermophilic Archaea have been found to contain dibiphytanyl tetraether lipids.Why are these lipids different from lipids present in non-hyperthermophiles? What special properties and structures do they confer?

Accepted Answer

The phytanyl units confer high thermosta

Question 11

The topoisomerase ________ introduces positive supercoils in DNA,which stabilizes DNA and prevents the DNA helix from denaturing at high temperatures.

Accepted Answer

A)  reverse ligase 
B)  ligase 
C)  DNA gyrase 
D)  reverse DNA gyrase 
A)  reverse ligase 
B)  ligase 
C)  DNA gyrase 
D)  reverse DNA gyrase

Question 12

There are many genes in archaeal genomes that have no known function.

Accepted Answer

A) True 
 B)False

Question 13

Pseudopeptidoglycan (pseudomurein)is part of the cell wall of some methanogens.

Accepted Answer

A) True 
 B)False

Question 14

Which statement is TRUE of methanogenic and extremely halophilic Archaea?

Accepted Answer

A)  The methanogens are obligate aerobes; the extreme halophiles are obligate anaerobes. 
B)  The methanogens are obligate anaerobes; the extreme halophiles are mostly obligate aerobes. 
C)  Both the methanogens and the extreme halophiles are obligate aerobes. 
D)  Both the methanogens and the extreme halophiles are obligate anaerobes. 
A)  The methanogens are obligate aerobes; the extreme halophiles are obligate anaerobes. 
B)  The methanogens are obligate anaerobes; the extreme halophiles are mostly obligate aerobes. 
C)  Both the methanogens and the extreme halophiles are obligate aerobes. 
D)  Both the methanogens and the extreme halophiles are obligate anaerobes.

Question 15

Compatible solutes counteract the tendency of a cell to become

Accepted Answer

A)  buoyant in high ionic strength environments. 
B)  hyperosmotic in low ionic strength environments. 
C)  dehydrated in high ionic strength environments. 
D)  viscous in low ionic strength environments. 
A)  buoyant in high ionic strength environments. 
B)  hyperosmotic in low ionic strength environments. 
C)  dehydrated in high ionic strength environments. 
D)  viscous in low ionic strength environments.

Question 16

The cytoplasmic proteins of Halobacterium are

Accepted Answer

A)  highly acidic. 
B)  highly basic. 
C)  generally neutral. 
D)  variable, depending on the species. 
A)  highly acidic. 
B)  highly basic. 
C)  generally neutral. 
D)  variable, depending on the species.

Question 17

Crenarchaeotes whose optimal growth temperature is over 80°C are called

Accepted Answer

A)  hyperthermophiles. 
B)  thermophiles. 
C)  extreme halophiles. 
D)  halophiles. 
A)  hyperthermophiles. 
B)  thermophiles. 
C)  extreme halophiles. 
D)  halophiles.

Question 18

Archaea is divided into three phyla.

Accepted Answer

A) True 
 B)False

Question 19

Thermoplasma grows either aerobically or anaerobically by sulfur respiration.

Accepted Answer

A) True 
 B)False

Question 20

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.

Exam 16: Diversity of Archaea

Most halobacteria are motile by means of lophotrichous flagella.

The cytoplasmic membrane of Thermoplasma contains a lipopolysaccharide-like material called lipoglycan which

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

With few exceptions,hyperthermophilic crenarchaeotes are obligate aerobes.

Though the known diversity of acetotrophic methanogens is low,they are ecologically significant in nature.

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

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

Approximately ________ of the Methanocaldococcus jannaschii genes have no counterparts in known genes from other sequenced organisms.

Explain why the presence of many Archaea has been confirmed only by community sampling of rRNA genes and not by culture in the laboratory.How has metagenomics helped to solve this problem?

Hyperthermophilic Archaea have been found to contain dibiphytanyl tetraether lipids.Why are these lipids different from lipids present in non-hyperthermophiles? What special properties and structures do they confer?

The topoisomerase ________ introduces positive supercoils in DNA,which stabilizes DNA and prevents the DNA helix from denaturing at high temperatures.

There are many genes in archaeal genomes that have no known function.

Pseudopeptidoglycan (pseudomurein)is part of the cell wall of some methanogens.

Which statement is TRUE of methanogenic and extremely halophilic Archaea?

Compatible solutes counteract the tendency of a cell to become

The cytoplasmic proteins of Halobacterium are

Crenarchaeotes whose optimal growth temperature is over 80°C are called

Archaea is divided into three phyla.

Thermoplasma grows either aerobically or anaerobically by sulfur respiration.

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

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