Chapter 26 Study Module

Why was the appearance of oxygen in the atmosphere a crucial event in the history of life?

Aerobic respiration became a possibility.

__________ is one of the two fundamental nutritional needs of all organisms.

Chemical energy

Which bacterial phylum is least likely to contain organisms that are pathogenic to humans?

Cyanobacteria

Which step of the nitrogen cycle represented in the figure is most critical to making nitrogen available to Earth's organisms and keeping those organisms alive?

Fixation by bacteria and archaea

What property of nitrate causes it to be a source of environmental pollution?

Nitrate dissolves readily in water.

A large proportion of archaeans are extremophiles, so called because they inhabit extreme environments with high acidity, salinity, and/or temperature. Such environments are thought to have been much more common on the primitive Earth. Thus, modern extremophiles survive only in places that their ancestors became adapted to long ago. Which of the following is, consequently, a valid statement about modern extremophiles, assuming that their habitats have remained relatively unchanged?

On a phylogenetic tree whose branch lengths are proportional to the amount of genetic change, the branches of the extremophiles should be shorter than the non-extremophilic archaeans.

Which of the following best describes what scientists have learned about pathogenic bacteria?

Pathogenic bacteria are more likely to be present in the digestive and respiratory tracts than in the nervous or circulatory systems.

Which of the following is a characteristic shared by archaea, bacteria, and eukarya?

Presence of ribosomes and RNA polymerase

What kind of evidence has recently made it necessary to assign the prokaryotes to either of two different domains, rather than assigning all prokaryotes to the same kingdom?

Ribosomal RNA (rRNA) genes and morphological evidence

What was the major finding discovered when the tree of life was first developed using base sequences of SSU RNAs?

The major divisions between life forms are between the domains Bacteria, Archaea, and Eukarya, and not between cells with a nucleus and those without.

Which statement is one of the four criteria that must be met to establish a causative link between a specific microbe and a disease, as proposed by Robert Koch?

The microbial organism must be isolated and grown in a pure culture outside the host organism.

Which of the following characteristics do biologists use to distinguish bacteria from archaea?

The types of molecules that make up their cell walls and membranes

Which statement is one of the two observations supporting the hypothesis that no free molecular oxygen existed for the first 2.3 billion years after the planet formed?

There was no plausible source of oxygen at the time the planet cooled to a solid state.

Which statement best describes the way(s) that bacteria and archaea produce ATP?

They use three processes, depending on whether they are phototrophs, chemoorganotrophs, or chemolithotrophs.

Which strategy would researchers use to isolate a previously undiscovered species of bacteria extracted in a small sample from a mile below Earth's surface, where specific growing conditions are known?

Use an enrichment culture.

Virulence is defined as the ____________.

ability to cause disease

Metagenomics has an enormous impact on the study of bacteria and archaea because it __________.

allows biologists to investigate previously unstudied bacteria and archaea

Bacteria produce antibiotics __________.

as a defense against other microorganisms

A key factor that allows some bacteria and archaea to be used for bioremediation is ____________.

their metabolic diversity