Exam 25: Bacteria, Archaea, and Viruses

Ninety percent of the cells of a human body are microbes-mostly prokaryotes and some microscopic eukaryotes.Which statement concerning human microbiomes is false?

A tiny percentage of prokaryotes are pathogens.All known pathogenic prokaryotes are bacteria, although many archaeal species live with humans and other eukaryotes.What explains this phenomenon?

Refer to the figure. In the 1990s, stomach ulcers were shown by Koch's postulates to be caused by the bacterium Helicobacter pylori.Which of the following is not one of Koch's postulates used to identify pathogens?

Refer to the figure. The phylogenetic tree shows that

Which of the following is a characteristic of Archaea, but not Bacteria or Eukarya?

An increase in cattle and rice cultivation would likely result an increase in greenhouse gases due to the presence of additional _______.

Legionella pneumophila is a Gram-negative bacterium that can cause Legionnaires' disease in immunocompromised individuals.Much of its success is attributed to its ability to form a biofilm in the lungs of its host.In this instance, what is the best explanation for the advantage conferred by biofilm formation?

Low-GC Gram-positive bacteria of the genus Staphylococcus-the staphylococci-

Which statement about cyanobacteria and the photosynthetic eukaryotes is false?

Which statement about single-stranded RNA that is the complement of the mRNA needed for protein translation is false?

Which of the following is a property of prokaryotes but not of eukaryotes?

An important set of rules for the determination of bacterial disease transmission is known as

Negative-sense single-stranded RNA viruses

Which nutritional category of bacteria can exist independently of other organisms?

Refer to the figure. In the figure, the phylogenetic tree

Which statement about high-GC Gram-positive bacteria (actinobacteria) is false?

Which of the following is a potential application of biofilms?

Chlamydias are known as "energy parasites." If a mutation were introduced into their _______ gene, their ability to acquire ATP from a host would be severely compromised.

You have a bacterial infection that is unresponsive to mild doses of common antibiotics.Your doctor prescribes a strong oral antibiotic known to disrupt chemical signaling in bacteria.Based on the mode of action of the new antibiotic prescribed, the doctor probably believes the bacteria exist in a _______.

A classmate argues that the three domains of life should be four domains, with the fourth domain containing viruses.Which is not an appropriate response to this argument?