Question 1

Which statement about denitrifiers is true?

Accepted Answer

A)  They fix atmospheric nitrogen (N2) into ammonia. 
B)  Organisms that act as denitrifiers are exclusively aerobic. 
C)  They are predominantly prokaryotic archaea. 
D)  During aerobic respiration, denitrifiers use nitrate or nitrite, rather than oxygen, as the final electron acceptor. 
E)  They release nitrogen into the atmosphere as nitrogen gas (N2). 
A)  They fix atmospheric nitrogen (N2) into ammonia. 
B)  Organisms that act as denitrifiers are exclusively aerobic. 
C)  They are predominantly prokaryotic archaea. 
D)  During aerobic respiration, denitrifiers use nitrate or nitrite, rather than oxygen, as the final electron acceptor. 
E)  They release nitrogen into the atmosphere as nitrogen gas (N2).

Question 2

Which of the following types of prokaryotes are most adversely affected by oxygen?

Accepted Answer

A)  Obligate aerobes 
B)  Obligate anaerobes 
C)  Facultative anaerobes 
D)  Aerotolerant aerobes 
E)  Photoautotrophs 
A)  Obligate aerobes 
B)  Obligate anaerobes 
C)  Facultative anaerobes 
D)  Aerotolerant aerobes 
E)  Photoautotrophs

Question 3

Refer to the figure, which shows the phylogenetic tree of major groups of living organisms.   Based on the figure, which statement about the evolutionary history of life is false?

Accepted Answer

A)  Eukarya shares a more recent common ancestor with prokaryotic Archaea than with Bacteria. 
B)  Bacteria shares a more recent common ancestor with Eukarya than with prokaryotic Archaea. 
C)  The common ancestor of Bacteria and Archaea predates that of Archaea and Eukarya. 
D)  All living organisms share a common origin. 
E)  An ancient prokaryotic species was the ancestor of all life on Earth. 
A)  Eukarya shares a more recent common ancestor with prokaryotic Archaea than with Bacteria. 
B)  Bacteria shares a more recent common ancestor with Eukarya than with prokaryotic Archaea. 
C)  The common ancestor of Bacteria and Archaea predates that of Archaea and Eukarya. 
D)  All living organisms share a common origin. 
E)  An ancient prokaryotic species was the ancestor of all life on Earth.

Question 4

Before biologists had the ability to decipher nucleotide sequences, prokaryotes were characterized according to several characteristics.Which of the following was not one of these characteristics?

Accepted Answer

A)  Nutritional requirements 
B)  Phenotypic characteristics, like shape or color 
C)  Sensitivity to antibiotics 
D)  Modes of locomotion 
E)  The presence of multiple genes 
A)  Nutritional requirements 
B)  Phenotypic characteristics, like shape or color 
C)  Sensitivity to antibiotics 
D)  Modes of locomotion 
E)  The presence of multiple genes

Question 5

_______ have a branched system of filaments and can superficially resemble fungi.

Accepted Answer

The answer of _______ have a branched system of filaments...

Question 6

Refer to the figure.   Crown gall disease is caused by Agrobacterium tumefaciens.This organism belongs to the group of bacteria known as

Accepted Answer

A)  chlamydias. 
B)  proteobacteria. 
C)  high-GC Gram-positive bacteria (actinobacteria). 
D)  endospore-forming low-GC Gram-positive bacteria (firmicutes). 
E)  hyperthermophilic bacteria. 
A)  chlamydias. 
B)  proteobacteria. 
C)  high-GC Gram-positive bacteria (actinobacteria). 
D)  endospore-forming low-GC Gram-positive bacteria (firmicutes). 
E)  hyperthermophilic bacteria.

Question 7

Refer to the figure.   Based on the spectroscopy data shown, which conclusion concerning light absorption by the different chlorophyll types found in purple sulfur bacteria and green algae is false?

Accepted Answer

A)  The chlorophyll found in purple sulfur bacteria absorbs light maximally at approximately 450 nm and 675 nm. 
B)  The chlorophyll found in purple sulfur bacteria has low light absorption at some wavelengths at which green algae have high absorption. 
C)  Maximum absorption of light is higher at certain wavelengths in purple sulfur bacteria than in green algae. 
D)  Bacteriochlorophyll is responsible for the absorbance spectrum of purple sulfur bacteria. 
E)  Maximum absorption of light by bacteriochlorophyll occurs at 375 nm and 875 nm. 
A)  The chlorophyll found in purple sulfur bacteria absorbs light maximally at approximately 450 nm and 675 nm. 
B)  The chlorophyll found in purple sulfur bacteria has low light absorption at some wavelengths at which green algae have high absorption. 
C)  Maximum absorption of light is higher at certain wavelengths in purple sulfur bacteria than in green algae. 
D)  Bacteriochlorophyll is responsible for the absorbance spectrum of purple sulfur bacteria. 
E)  Maximum absorption of light by bacteriochlorophyll occurs at 375 nm and 875 nm.

Question 8

Match the name of the bacteria from the list below with the description that follows.

Accepted Answer

A)  Cyanobacteria 
B)  Spirochetes 
C)  Chlamydias 
D)  Gram-negative, rod-shaped bacteria 
E)  Actinobacteria These bacteria photosynthesize using chlorophyll a, produced the oxygen of Earth's early atmosphere, and contain photosynthetic lamellae. 
A)  Cyanobacteria 
B)  Spirochetes 
C)  Chlamydias 
D)  Gram-negative, rod-shaped bacteria 
E)  Actinobacteria These bacteria photosynthesize using chlorophyll a, produced the oxygen of Earth's early atmosphere, and contain photosynthetic lamellae.

Question 9

Why aren't viruses placed on the tree of life for classification, as most other organisms are?

Accepted Answer

There are many factors that make viral p

Question 10

Which statement about prokaryotic archaea is false?

Accepted Answer

A)  Some species inhabit environments with extreme salinity and low oxygen. 
B)  Their cell walls contain peptidoglycan, a unique archaeal feature. 
C)  Their ribosomes differ from those of eukaryotes. 
D)  Some species are obligate anaerobes that produce most of the atmospheric methane. 
E)  Some species thrive at 75F1F1F1S1F1F1F10C heat and become metabolically inactive at 55F1F1F1S1F1F1F10C (131F1F1F1S1F1F1F10F). 
A)  Some species inhabit environments with extreme salinity and low oxygen. 
B)  Their cell walls contain peptidoglycan, a unique archaeal feature. 
C)  Their ribosomes differ from those of eukaryotes. 
D)  Some species are obligate anaerobes that produce most of the atmospheric methane. 
E)  Some species thrive at 75F1F1F1S1F1F1F10C heat and become metabolically inactive at 55F1F1F1S1F1F1F10C (131F1F1F1S1F1F1F10F).

Question 11

You have learned that bioluminescence in Vibrio is a density-dependent phenomenon that depends on the presence of a signal molecule, its receptor, and luciferase.Design an experiment or application that takes advantage of this quorum-sensing communication system.

Accepted Answer

There are many possible experiments or a

Question 12

Which statement concerning nitrogen cycling is false?

Accepted Answer

A)  Prokaryotic nitrogen fixers play a major role in nitrogen cycling in the world's ecosystems. 
B)  Denitrifiers convert nitrate ions into nitrogen gas, which is released into the atmosphere. 
C)  Without denitrification, nitrogen would leach from the soil into lakes and rivers. 
D)  Nitrogen fixers convert atmospheric nitrogen gas into a usable chemical form (ammonia). 
E)  Nitrate is oxidized to ammonia in soil and in seawater by chemoautotrophic bacteria called nitrifiers. 
A)  Prokaryotic nitrogen fixers play a major role in nitrogen cycling in the world's ecosystems. 
B)  Denitrifiers convert nitrate ions into nitrogen gas, which is released into the atmosphere. 
C)  Without denitrification, nitrogen would leach from the soil into lakes and rivers. 
D)  Nitrogen fixers convert atmospheric nitrogen gas into a usable chemical form (ammonia). 
E)  Nitrate is oxidized to ammonia in soil and in seawater by chemoautotrophic bacteria called nitrifiers.

Question 13

One popular hypothesis for the origin of viruses is that they evolved

Accepted Answer

A)  only once in evolutionary history. 
B)  from escaped genomic components. 
C)  from reduced cytoplasmic organelles. 
D)  twice in evolutionary history. 
E)  from bacterial conjugation. 
A)  only once in evolutionary history. 
B)  from escaped genomic components. 
C)  from reduced cytoplasmic organelles. 
D)  twice in evolutionary history. 
E)  from bacterial conjugation.

Question 14

Which statement about prokaryotes that use chlorophyll a as their photosynthetic pigment is true?

Accepted Answer

A)  They use hydrogen sulfide (H2S) as an electron acceptor. 
B)  They always produce O2. 
C)  They can grow under dense mats of algae. 
D)  They can absorb lights of longer wavelengths than prokaryotes that use bacteriochlorophyll. 
E)  They include cyanobacteria. 
A)  They use hydrogen sulfide (H2S) as an electron acceptor. 
B)  They always produce O2. 
C)  They can grow under dense mats of algae. 
D)  They can absorb lights of longer wavelengths than prokaryotes that use bacteriochlorophyll. 
E)  They include cyanobacteria.

Question 15

_______ are viruses that infect bacteria and have been used in medicine to fight bacterial infections

Accepted Answer

The answer of _______ are viruses that infect bacteria and...

Question 16

Retroviruses insert their genomes into those of their hosts.Which statement best describes a scenario that relates to this characteristic?

Accepted Answer

A)  Some DNA viruses may have evolved from reduced cellular organisms. 
B)  Retroviruses are only known to infect vertebrates. 
C)  DNA from proviruses can provide a record of ancient viral infections that plagued human ancestors. 
D)  Some retrovirus sequences code for bacteria. 
E)  Some retrovirus sequences code for bacteriophages. 
A)  Some DNA viruses may have evolved from reduced cellular organisms. 
B)  Retroviruses are only known to infect vertebrates. 
C)  DNA from proviruses can provide a record of ancient viral infections that plagued human ancestors. 
D)  Some retrovirus sequences code for bacteria. 
E)  Some retrovirus sequences code for bacteriophages.

Question 17

Several human bacterial diseases, including tetanus, cholera, and bubonic plague, are induced by soluble proteins called _______ that are released by the living bacteria as they multiply.

Accepted Answer

The answer of Several human bacterial diseases, including tetanus, cholera,...

Question 18

Why is reverse transcriptase essential for a retrovirus to successfully infect a host?

Accepted Answer

A)  It creates a complementary cDNA copy of the viral RNA genome. 
B)  It creates the mRNA necessary for expression of viral genes. 
C)  It is responsible for integrating the viral genome into the host genome. 
D)  It is responsible for the evasion of host defense mechanisms. 
E)  It creates a complementary cDNA copy of host genes to block their translation. 
A)  It creates a complementary cDNA copy of the viral RNA genome. 
B)  It creates the mRNA necessary for expression of viral genes. 
C)  It is responsible for integrating the viral genome into the host genome. 
D)  It is responsible for the evasion of host defense mechanisms. 
E)  It creates a complementary cDNA copy of host genes to block their translation.

Question 19

Some normally aerobic bacteria, which include species of the genera Bacillus and Pseudomonas, use nitrate (NO3-) as an electron acceptor in place of oxygen if they are kept under anaerobic conditions.Which of the following statements concerning these ecologically important bacteria is false?

Accepted Answer

A)  They act as denitrifiers. 
B)  They release nitrogen to the atmosphere as nitrogen gas (N2). 
C)  Without their conversion of soil nitrogen to atmospheric gas, soil nitrogen would leach into lakes and rivers. 
D)  They convert ammonia (NH3) to nitrate (NO3-), which is available to plants. 
E)  They convert nitrate ions to nitrogen gas (N2). 
A)  They act as denitrifiers. 
B)  They release nitrogen to the atmosphere as nitrogen gas (N2). 
C)  Without their conversion of soil nitrogen to atmospheric gas, soil nitrogen would leach into lakes and rivers. 
D)  They convert ammonia (NH3) to nitrate (NO3-), which is available to plants. 
E)  They convert nitrate ions to nitrogen gas (N2).

Question 20

RNA retroviruses

Accepted Answer

A)  have only a few genes, including one that allows them to make mRNA from their genome. 
B)  are responsible for causing plant diseases and are referred to as mosaic viruses. 
C)  regenerate themselves using reverse transcription. 
D)  are polyphyletic, and some have more than a million base pairs. 
E)  have distinct lipids in their plasma membranes. 
A)  have only a few genes, including one that allows them to make mRNA from their genome. 
B)  are responsible for causing plant diseases and are referred to as mosaic viruses. 
C)  regenerate themselves using reverse transcription. 
D)  are polyphyletic, and some have more than a million base pairs. 
E)  have distinct lipids in their plasma membranes.

Exam 25: Bacteria, Archaea, and Viruses

Which statement about denitrifiers is true?

Which of the following types of prokaryotes are most adversely affected by oxygen?

Refer to the figure, which shows the phylogenetic tree of major groups of living organisms. Based on the figure, which statement about the evolutionary history of life is false?

Before biologists had the ability to decipher nucleotide sequences, prokaryotes were characterized according to several characteristics.Which of the following was not one of these characteristics?

_______ have a branched system of filaments and can superficially resemble fungi.

Refer to the figure. Crown gall disease is caused by Agrobacterium tumefaciens.This organism belongs to the group of bacteria known as

Refer to the figure. Based on the spectroscopy data shown, which conclusion concerning light absorption by the different chlorophyll types found in purple sulfur bacteria and green algae is false?

Match the name of the bacteria from the list below with the description that follows.

Why aren't viruses placed on the tree of life for classification, as most other organisms are?

Which statement about prokaryotic archaea is false?

You have learned that bioluminescence in Vibrio is a density-dependent phenomenon that depends on the presence of a signal molecule, its receptor, and luciferase.Design an experiment or application that takes advantage of this quorum-sensing communication system.

Which statement concerning nitrogen cycling is false?

One popular hypothesis for the origin of viruses is that they evolved

Which statement about prokaryotes that use chlorophyll a as their photosynthetic pigment is true?

_______ are viruses that infect bacteria and have been used in medicine to fight bacterial infections

Retroviruses insert their genomes into those of their hosts.Which statement best describes a scenario that relates to this characteristic?

Several human bacterial diseases, including tetanus, cholera, and bubonic plague, are induced by soluble proteins called _______ that are released by the living bacteria as they multiply.

Why is reverse transcriptase essential for a retrovirus to successfully infect a host?

Some normally aerobic bacteria, which include species of the genera Bacillus and Pseudomonas, use nitrate (NO3-) as an electron acceptor in place of oxygen if they are kept under anaerobic conditions.Which of the following statements concerning these ecologically important bacteria is false?

RNA retroviruses

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Cells: the Working Units of Life

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Some normally aerobic bacteria, which include species of the genera Bacillus and Pseudomonas, use nitrate (NO₃^-) as an electron acceptor in place of oxygen if they are kept under anaerobic conditions.Which of the following statements concerning these ecologically important bacteria is false?