Exam 20: The Archaea

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

Defining features of the halobacteria include

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.

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

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

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

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

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

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

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

Many archaeal chromosomes include plasmids.

Methanogens can live only in __________ environments.

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

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

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

Archaeal cell walls

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

The photosynthetic membrane of Halobacterium salinarium contains

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)

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