Deck 18: The Archaea

Question 1

Some archaeons are symbionts in animal digestive tracts.

Answer 1

True

Question 2

Archaeal promoters are most similar to those of

A) viruses.
B) bacteria.
C) eukaryotes.
D) both viruses and bacteria.

Answer 2

C

Question 3

The DNA of some archaeons is stabilized by association with archaeal histone proteins forming particles resembling eucaryotic nucleosomes.

Answer 3

True

Question 4

Many archaeal chromosomes include plasmids.

Question 5

The Crenarchaeota and Euryarchaeota are

A) the two phyla of the Archaea.
B) very closely related based on 16S rRNA comparisons.
C) photosynthetic Archaea.
D) now classified with the bacteria based on genomic sequence analysis.

Question 6

Archaeons are not known to incorporate (fix) carbon dioxide.

Question 7

Archaeons have been isolated from temperate and cold environments.

Question 8

Glycogen is used as a major carbon and energy reserve by some archaeons.

Question 9

A peptidoglycan-like polymer found in the cell walls of some Archaea is called __________.

Question 10

Which of the following is not true about archaeal ribosomes?

A) They are 70S like bacterial ribosomes.
B) They may possess ribosome binding sites homologous to bacterial Shine-Dalgarno sequences.
C) They have similar antibiotic sensitivities to those of bacteria.
D) All of these are true about archaeal ribosomes.

Question 11

The primary lipid components of the membranes of extreme thermophiles are

A) sulfolipids.
B) cholesterol.
C) 40 carbon diglycerol tetraethers.
D) 20 carbon diglycerol diethers.

Question 12

Unlike other prokaryotes, archaeons (except Sulfolobus) have two origins of replication.

Question 13

Some members of the Archaea lack a cell wall.

Question 14

A large number of the genes shared only by bacteria and Archaea produce proteins that are involved in ____________ ___________.

Question 15

The RNA polymerase enzymes of the Archaea are more similar to eukaryotic enzymes than to bacterial enzymes.

Question 16

Some methanogenic Archaea are capable of fixing nitrogen.

Question 17

Most Archaea capable of metabolizing glucose do so using a modified _________ -________ pathway.

Question 18

Unlike members of the Bacteria, most archaeons have linear chromosomes with multiple origins of replication.

Question 19

Because archaeons lack peptidoglycan in their cell walls

A) some have an outer layer of complex polysaccharide.
B) some have an outer layer of protein.
C) they must always be grown in isotonic medium.
D) some have an outer layer of complex polysaccharide and some have an outer layer of protein

Question 20

Most archaeal mRNAs like those of eukaryotes are spliced.

Question 21

Which of the following contribute(s) to the differences between the Archaea and the bacteria?

A) Archaea lack muramic acid.
B) Archaea have isopranyl glycerol ethers rather than fatty acid esters in their membrane lipids.
C) Archaea differ from bacteria in their tRNA composition, ribosome structure, and antibiotic sensitivity
D) all of these

Question 22

Methanogenic Archaea are

A) obligate anaerobes that produce methane.
B) obligate anaerobes that consume methane.
C) obligate aerobes that produce methane.
D) obligate aerobes that consume methane.

Question 23

Methanogens may contribute to the greenhouse effect and global warming due to methane production.

Question 24

If the NaCl concentration drops below 1.5 M the cell walls of Halobacterium become more rigid.

Question 25

Methanogens can live only in __________ environments.

A) aerobic
B) anaerobic
C) microaerophilic
D) all of these

Question 26

Archaeal membranes contain which of the following lipids?

A) phospholipids
B) sulfolipids
C) glycolipids
D) all of these

Question 27

Which of the following genera of the Archaea do not have cell walls?

A) Halobacterium
B) Thermoplasma
C) Thermococcus
D) none of the choices

Question 28

Archaeal sulfate reducers use elemental sulfur as an electron acceptor.

Question 29

The Archaea generally lack which of the following that are normally found in gram-negative bacteria?

A) outer membrane
B) a complex peptidoglycan network
C) lipopolysaccharide
D) all of the choices

Question 30

If the NaCl concentration drops below 1.5 M the cell walls of Halobacterium disintegrate.

Question 31

Many species in the phylum Crenarchaeota are considered extreme thermophiles or ________________, which can grow at temperatures above 100 degrees
C.

Question 32

Archaeal cell walls

A) are disrupted by treatment with lysozyme or penicillin.
B) are similar to those of gram-negative bacteria.
C) lack murein and D-amino acids.
D) include orthomureine.

Question 33

Some members of the genus Pyrodictum can grow quite well above the boiling point of water.

Question 34

Although Sulfolobus solfataricus grows at pH 2 to 4, it maintains a cytoplasmic pH of about 2, thereby generating a large pH gradient across the plasma membrane.

Question 35

Archaeoglobales have been isolated from marine hydrothermal vents.

Question 36

Which of the following is/are true of most of the extreme thermophilic Archaea in the phylum of Crenarchaeota?

A) They are sulfur dependent.
B) They are acidophiles.
C) Their cell walls contain lipoprotein and carbohydrate.
D) Unlike most other Archaea, their membrane lipids are similar to those of the bacteria.
E) They are sulfur dependent, they are acidophiles, and their cell walls contain lipoprotein and carbohydrate

Question 37

An organism with a temperature growth optimum near 80 $\degree$ C and a pH growth optimum between 2 and 3 is usually referred to as a(n)

A) halophile.
B) thermoacidophile.
C) thermophile.
D) thermoalkalophile.

Question 38

Picrophilus has a pH optimum below 1 and can even grow at or near pH 0.

Question 39

Thermophylic members of the phylum _____________ can grow in geothermally heated water or soils that contain elemental sulfur.

Question 40

The Archaea do not use __________ as a mechanism for reproduction.

A) binary fission
B) budding
C) mitosis
D) fragmentation

Question 41

Substrates used by methanogens include H₂ and CO₂ as well as short-chain organic compounds such as

A) formate.
B) acetate.
C) methanol.
D) all of the above are used by methanogens.

Question 42

Which of the following is currently the largest group of cultured Archaea?

A) extreme halophiles
B) methanogens
C) extreme thermophiles
D) sulfate reducers

Question 43

Methanogens link ATP synthesis to methanogenesis by

A) substrate-level phosphorylation.
B) the reverse TCA cycle.
C) the use of bacteriorhodopsin.
D) electron transport to generate proton motive force

Question 44

Defining features of the halobacteria include

A) absolute dependence on temperatures above 65ºC for growth.
B) the production of methane.
C) absolute dependence on a high concentration of NaCl for growth.
D) absolute dependence on low pH conditions for growth.

Question 45

The cell membranes of wall-less archaeons are strengthened by

A) diglycerol ethers.
B) glycoprotein or protein layers.
C) pseudomurein.
D) diglycerol tetraethers.

Question 46

Diglycerol tetraether lipids

A) are a characteristic feature of thermophilic Archaea.
B) tend to make the membrane less rigid.
C) are found in some bacteria and some Archaea.
D) form typical bilayer membranes in thermophilic Archaea of the genus Thermoplasma.

Question 47

Autotrophy has been observed among the

A) methanogens.
B) extreme thermophiles.
C) cyanobacteria.
D) all of the choices

Question 48

The photosynthetic membrane of Halobacterium salinarium contains

A) bacteriorhodopsin.
B) chlorophyll a and b.
C) bacteriochlorophyll.
D) archaeochlorophyll.

Question 49

Which of the following do methanogens not use to form methane?

A) carbon dioxide
B) formate
C) acetate
D) phosphate

Question 50

A modified cell membrane that carries out photosynthesis using bacteriorhodopsin in the absence of chlorophyll is called a __________ membrane.

A) colorless
B) orange
C) purple
D) green

Question 51

Which of the following is true about the cell-wall-less archaeal genus Thermoplasma?

A) They are spherical at temperatures below 59 $\degree$ C.
B) They are filamentous at temperatures at 59 $\degree$ C and higher.
C) They are non-motile.
D) They are spherical at temperatures below 59 $\degree$ C and they are filamentous at temperatures at 59 $\degree$ C and higher.

Question 52

An organism that requires at least 1.5 M NaCl in order to grow is referred to as a(n)

A) facultative halophile.
B) extreme halophile.
C) sodiophile.
D) barophile.