BIO 151---Exam 1 (Chapter 26)

For the first __________ years of Earth's existence, the percentage of oxygen in the atmosphere was __________.

2.3 billion, nearly zero

Which starting materials do bacteria and archaea employ in the process of fermentation?

A variety of organic compounds, both sugars and nonsugars

Which of the following are also referred to as "high-GC Gram positives"?

Actinobacteria

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

Aerobic respiration became a possibility.

Which of the following correctly identifies a metabolic difference that separates bacteria and archaea from eukaryotes?

Bacteria and archaea can use ethanol, acetate, and even amino acids in fermentation.

__________ 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 group of microbes is responsible for first adding oxygen to early Earth's nitrogen and carbon dioxide atmosphere?

Cyanobacteria

Which of the following organisms were formerly known as blue-green algae?

Cyanobacteria

If the vertical axis of the figure refers to relative fitness, then which of the following is the most valid and accurate measure of fitness?

E. coli replicates by binary fission, always yielding two daughter cells from each parent cell. The only way to increase the bacterial numbers, then, is to decrease the generation time and maximize the number of generations per unit time.

What drug should a doctor prescribe for a person with an infection caused by a Gram-negative cell?

Erythromycin

Which term best describes what has occurred among the experimental populations of cells over this eight-year period?

Evolution

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

How is a Gram-positive cell wall different from a Gram-negative cell wall?

Gram-negative cell walls have a thin layer of peptidoglycan, but Gram-negative cell walls have a thick layer of peptidoglycan.

How is a Gram-positive cell wall different from a Gram-negative cell wall?

Gram-negative cell walls have two membranes, whereas Gram-positive cell walls have one.

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

Nitrate dissolves readily in water.

What distinguishes proteobacteria?

None of them are capable of oxygenic photosynthesis.

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 traits differentiates bacteria from archaea?

Plasma membrane lipids

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

Which of the following traits differentiates bacteria from archaea?

Structure of RNA polymerase

Which organisms make up an estimated 10 percent of the world's total mass of living material?

Suboceanic marine microbes

Which of the following habitats is unable to support microbe growth?

Temperature of 300°C (deep-sea vent water)

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 of the following is not one of Robert Koch's postulates?

The microbe must be prokaryotic.

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.

What differentiates archaea from both bacteria and eukarya?

The nature of the plasma membrane

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.

What is the natural role of antibiotics?

To reduce competition for nutrients and other resources among microbes

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.

Which molecule is used as a source of electrons for photosynthesis in both cyanobacteria and plants?

Water

A patient is clearly sick, but researchers cannot grow a causative pathogen in culture, nor can they identify any DNA-based sequences to identify the organism. Is this a violation of Koch's postulates?

Yes, because Koch's postulates require a microbe to be grown in culture, nor can they identify any DNA-based sequences to identify the organism.

A patient has a microbe in his stool that causes typhoid fever in many people, yet he has no symptoms of the disease. Is this a violation of Koch's postulates?

Yes, because one of Koch's postulates indicates that if the person has been exposed to the virulent microbe, then the disease symptoms should appear.

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

Cellular respiration requires __________.

an electron donor and an electron acceptor

Photosynthesis that does not produce oxygen is called __________.

anoxygenic, because water is not used as the electron source

Molecules that kill bacteria or stop them from growing are called __________.

antibiotics

Bacteria produce antibiotics __________.

as a defense against other microorganisms

The process of converting N2 into ammonia is called __________.

nitrogen fixation

A microbe that uses sunlight as an energy source and carbon dioxide as a carbon source is a __________.

photoautotroph

Compare the bacteria in the figure in generation one and generation 20,000. The bacteria in generation one likely have a greater ____________.

reliance on glycolytic enzymes

In eukaryotes, cellular respiration uses the electron transport chain in the mitochondria for efficient ATP synthesis. In bacteria, ___________.

the electron transport chain is located in the plasma membrane

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

their metabolic diversity

Bioremediation involves __________.

using bacteria to clean up polluted sites