Question 1

Differentiate between the following terms:
obligate anaerobe / obligate aerobe
photoautotroph / photoheterotroph
chemoautotroph / chemoheterotroph

Accepted Answer

Obligate anaerobes die in the presence o

Question 2

Evidence supporting the lokiarchaeotes as the closest relatives of the eukaryotes is based on the presence of certain genes in the lokiarchaeote genome.Scientists are confident of this newly described relationship because the genes found

Accepted Answer

A)  in these prokaryotic archaea confer a fitness advantage. 
B)  are involved in fundamental biological processes that take place in eukaryotes. 
C)  are conserved in all three domains of life. 
D)  are unique to prokaryotic archaea. 
E)  are more closely related to those found in bacteria. 
A)  in these prokaryotic archaea confer a fitness advantage. 
B)  are involved in fundamental biological processes that take place in eukaryotes. 
C)  are conserved in all three domains of life. 
D)  are unique to prokaryotic archaea. 
E)  are more closely related to those found in bacteria.

Question 3

Double-stranded DNA viruses

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.

Question 4

When accumulating in a biofilm, prokaryotes release signaling molecules.A drug that incapacitates these molecules could

Accepted Answer

A)  prevent dental plaque. 
B)  encourage development of dental plaque. 
C)  lead to the formation of biofilms between species that do not normally occur together. 
D)  kill harmful bacteria. 
E)  result in a proliferation of bacterial species. 
A)  prevent dental plaque. 
B)  encourage development of dental plaque. 
C)  lead to the formation of biofilms between species that do not normally occur together. 
D)  kill harmful bacteria. 
E)  result in a proliferation of bacterial species.

Question 5

The CDC has enlisted your help in controlling the spread of a highly contagious, rapidly evolving, drug-resistant bacterium released during the desert excavation of an ancient civilization.What approach do you tell them to take?

Accepted Answer

A)  Use alcohol or bleach to sterilize the affected areas 
B)  Try to irradiate the bacterium with UV light 
C)  Introduce a bacteriophage that is known to attack a closely related bacterial species 
D)  Develop a new class of antibiotics that the pathogen has not yet encountered 
E)  Introduce nonpathogenic bacteria to compete with the pathogen for resources 
A)  Use alcohol or bleach to sterilize the affected areas 
B)  Try to irradiate the bacterium with UV light 
C)  Introduce a bacteriophage that is known to attack a closely related bacterial species 
D)  Develop a new class of antibiotics that the pathogen has not yet encountered 
E)  Introduce nonpathogenic bacteria to compete with the pathogen for resources

Question 6

After culturing a bacterial species isolated from a skin lesion, a scientist was unable to infect a new host with the bacterial culture and was thus unable to satisfy Koch's postulates.In this instance, the bacterium that was cultured is not considered a _______.

Accepted Answer

The answer of After culturing a bacterial species isolated from...

Question 7

Refer to the figure, which shows a scatterplot of genome size versus number of protein-coding genes found in different classes of microbes.   Based on these data, state and justify the most likely origin of the mimivirus, and present an alternative hypothesis for the origin of this and other viruses.

Accepted Answer

The genome size and number of protein-co

Question 8

Which category of organisms depends on organic molecules as the source of both energy and carbon?

Accepted Answer

A)  Photoautotrophs 
B)  Chemoautotrophs 
C)  Photoheterotrophs 
D)  Chemoheterotrophs 
E)  Nitrifiers 
A)  Photoautotrophs 
B)  Chemoautotrophs 
C)  Photoheterotrophs 
D)  Chemoheterotrophs 
E)  Nitrifiers

Question 9

Comparisons of entire genomes among prokaryotes have revealed a stable core of crucial genes that are unaffected by lateral gene transfer.Which statement concerning this discovery is false?

Accepted Answer

A)  Genes involved in fundamental cellular processes are unlikely to be replaced by lateral gene transfer. 
B)  Lateral gene transfer enables rapid acquisition of traits adapted to specific environments. 
C)  The discovery will facilitate understanding of phylogenetic relationships of prokaryotes. 
D)  The results must be treated cautiously because of the small percentage of prokaryotes for which entire genomes are known. 
E)  Lateral gene transfer makes reconstructing evolutionary patterns among prokaryotes almost impossible. 
A)  Genes involved in fundamental cellular processes are unlikely to be replaced by lateral gene transfer. 
B)  Lateral gene transfer enables rapid acquisition of traits adapted to specific environments. 
C)  The discovery will facilitate understanding of phylogenetic relationships of prokaryotes. 
D)  The results must be treated cautiously because of the small percentage of prokaryotes for which entire genomes are known. 
E)  Lateral gene transfer makes reconstructing evolutionary patterns among prokaryotes almost impossible.

Question 10

Which of the following statements is false?

Accepted Answer

A)  There may be millions or hundreds of millions of prokaryotic species on Earth. 
B)  The number of individual prokaryotes may be 100 million times greater than the number of stars in the visible universe. 
C)  The individual bacteria living in your intestinal tract outnumber all humans who have ever lived. 
D)  Prokaryotes were alone on the early Earth for a very long time, adapting to new environments. 
E)  Prokaryote ecology is irrelevant to that of other organisms on Earth. 
A)  There may be millions or hundreds of millions of prokaryotic species on Earth. 
B)  The number of individual prokaryotes may be 100 million times greater than the number of stars in the visible universe. 
C)  The individual bacteria living in your intestinal tract outnumber all humans who have ever lived. 
D)  Prokaryotes were alone on the early Earth for a very long time, adapting to new environments. 
E)  Prokaryote ecology is irrelevant to that of other organisms on Earth.

Question 11

Observable phenotypic characteristics, such as a reaction to the Gram stain, are less useful than molecular traits for understanding the evolutionary relationships of prokaryotes.Which statement about the importance of rRNA to the classification of organisms is false?

Accepted Answer

A)  Because rRNA is ancient, it is useful for evolutionary studies. 
B)  All free-living organisms have rRNA, making it useful for evolutionary studies. 
C)  Because it plays the same role in translation in all organisms, rRNA is useful for evolutionary studies. 
D)  Unique sequences in rRNA are useful for distinguishing relationships at the domain level, but not at lower taxonomic levels. 
E)  Because rRNA has evolved slowly and sequence similarities between groups of organisms are easily found, it is useful for evolutionary studies. 
A)  Because rRNA is ancient, it is useful for evolutionary studies. 
B)  All free-living organisms have rRNA, making it useful for evolutionary studies. 
C)  Because it plays the same role in translation in all organisms, rRNA is useful for evolutionary studies. 
D)  Unique sequences in rRNA are useful for distinguishing relationships at the domain level, but not at lower taxonomic levels. 
E)  Because rRNA has evolved slowly and sequence similarities between groups of organisms are easily found, it is useful for evolutionary studies.

Question 12

Extreme halophiles absorb light to form ATP, using a molecule called microbial rhodopsin.This molecule is formed by combining a protein with _______, a pigment also found in the vertebrate eye.

Accepted Answer

A)  NaCl 
B)  ammonia 
C)  retinal 
D)  chlorophyll 
E)  sulfur 
A)  NaCl 
B)  ammonia 
C)  retinal 
D)  chlorophyll 
E)  sulfur

Question 13

Which of the following can form endospores?

Accepted Answer

A)  All low-GC Gram-positive bacteria (firmicutes) 
B)  Clostridium and Staphylococcus 
C)  Clostridium and Bacillus 
D)  Bacillus and the mycoplasmas 
E)  Staphylococcus and Bacillus 
A)  All low-GC Gram-positive bacteria (firmicutes) 
B)  Clostridium and Staphylococcus 
C)  Clostridium and Bacillus 
D)  Bacillus and the mycoplasmas 
E)  Staphylococcus and Bacillus

Question 14

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 use axial filaments to move and include the bacterium that causes syphilis. 
A)  Cyanobacteria 
B)  Spirochetes 
C)  Chlamydias 
D)  Gram-negative, rod-shaped bacteria 
E)  Actinobacteria These bacteria use axial filaments to move and include the bacterium that causes syphilis.

Question 15

The most recent identified ancestor of eukaryotes is a group of Archaea called the lokiarchaeotes.The evidence of this phylogenetic relationship is based on the presence of certain genes in the lokiarchaeote genome.These genes

Accepted Answer

A)  confer a fitness advantage to archaea and are likely a result of horizontal gene transfer. 
B)  are unique to prokaryotic archaea. 
C)  are conserved in the two major divisions of life. 
D)  are involved in fundamental biological processes that take place in eukaryotes. 
E)  are more closely related to genes found in bacteria than to those found in eukaryotes. 
A)  confer a fitness advantage to archaea and are likely a result of horizontal gene transfer. 
B)  are unique to prokaryotic archaea. 
C)  are conserved in the two major divisions of life. 
D)  are involved in fundamental biological processes that take place in eukaryotes. 
E)  are more closely related to genes found in bacteria than to those found in eukaryotes.

Question 16

Refer to the figure.   Label the cells as Gram-positive or Gram-negative, and identify each portion of the structure.

Accepted Answer

Top figure is Gram-positive; bottom figu

Question 17

Chemoautotrophs

Accepted Answer

A)  use organic molecules as a source of energy. 
B)  cannot incorporate CO2 into carbohydrates. 
C)  require light to grow. 
D)  include only bacterial species. 
E)  oxidize inorganic molecules as a source of energy. 
A)  use organic molecules as a source of energy. 
B)  cannot incorporate CO2 into carbohydrates. 
C)  require light to grow. 
D)  include only bacterial species. 
E)  oxidize inorganic molecules as a source of energy.

Question 18

The Gram-staining method is useful for classifying all bacteria that

Accepted Answer

A)  have two plasma membranes. 
B)  associate to form chains, plates, or clusters of cells. 
C)  have cell walls with at least some peptidoglycan. 
D)  are prokaryotic. 
E)  form endospores. 
A)  have two plasma membranes. 
B)  associate to form chains, plates, or clusters of cells. 
C)  have cell walls with at least some peptidoglycan. 
D)  are prokaryotic. 
E)  form endospores.

Question 19

An archaeal species, taken near a hydrothermal vent, survives and even multiplies at 121°C.This indicates that at least some members of this group can live under severe conditions.Which of the following does not characterize the archaea?

Accepted Answer

A)  All archaea lack peptidoglycan in their cell walls. 
B)  Some archaea reduce carbon dioxide. 
C)  The environments where the archaea live tend to be extreme. 
D)  Most lipids in archaeal membranes contain unbranched long-chain fatty acids connected to glycerol molecules by ester linkages. 
E)  Methanogenic euryarchaeotes release approximately 2 billion tons of methane gas into Earth's atmosphere each year. 
A)  All archaea lack peptidoglycan in their cell walls. 
B)  Some archaea reduce carbon dioxide. 
C)  The environments where the archaea live tend to be extreme. 
D)  Most lipids in archaeal membranes contain unbranched long-chain fatty acids connected to glycerol molecules by ester linkages. 
E)  Methanogenic euryarchaeotes release approximately 2 billion tons of methane gas into Earth's atmosphere each year.

Question 20

Which statement about Gram-positive bacteria is true?

Accepted Answer

A)  They stain blue to purple and have walls with a relatively high concentration of peptidoglycan. 
B)  They stain pink to red and have relatively little peptidoglycan in their cell walls. 
C)  They weigh more than a gram. 
D)  They were discovered before Gram-negative bacteria. 
E)  They have no peptidoglycan in their cell walls. 
A)  They stain blue to purple and have walls with a relatively high concentration of peptidoglycan. 
B)  They stain pink to red and have relatively little peptidoglycan in their cell walls. 
C)  They weigh more than a gram. 
D)  They were discovered before Gram-negative bacteria. 
E)  They have no peptidoglycan in their cell walls.

Exam 25: Bacteria, Archaea, and Viruses

Differentiate between the following terms: obligate anaerobe / obligate aerobe photoautotroph / photoheterotroph chemoautotroph / chemoheterotroph

Evidence supporting the lokiarchaeotes as the closest relatives of the eukaryotes is based on the presence of certain genes in the lokiarchaeote genome.Scientists are confident of this newly described relationship because the genes found

Double-stranded DNA viruses

When accumulating in a biofilm, prokaryotes release signaling molecules.A drug that incapacitates these molecules could

The CDC has enlisted your help in controlling the spread of a highly contagious, rapidly evolving, drug-resistant bacterium released during the desert excavation of an ancient civilization.What approach do you tell them to take?

After culturing a bacterial species isolated from a skin lesion, a scientist was unable to infect a new host with the bacterial culture and was thus unable to satisfy Koch's postulates.In this instance, the bacterium that was cultured is not considered a _______.

Refer to the figure, which shows a scatterplot of genome size versus number of protein-coding genes found in different classes of microbes. Based on these data, state and justify the most likely origin of the mimivirus, and present an alternative hypothesis for the origin of this and other viruses.

Which category of organisms depends on organic molecules as the source of both energy and carbon?

Comparisons of entire genomes among prokaryotes have revealed a stable core of crucial genes that are unaffected by lateral gene transfer.Which statement concerning this discovery is false?

Which of the following statements is false?

Observable phenotypic characteristics, such as a reaction to the Gram stain, are less useful than molecular traits for understanding the evolutionary relationships of prokaryotes.Which statement about the importance of rRNA to the classification of organisms is false?

Extreme halophiles absorb light to form ATP, using a molecule called microbial rhodopsin.This molecule is formed by combining a protein with _______, a pigment also found in the vertebrate eye.

Which of the following can form endospores?

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

The most recent identified ancestor of eukaryotes is a group of Archaea called the lokiarchaeotes.The evidence of this phylogenetic relationship is based on the presence of certain genes in the lokiarchaeote genome.These genes

Refer to the figure. Label the cells as Gram-positive or Gram-negative, and identify each portion of the structure.

Chemoautotrophs

The Gram-staining method is useful for classifying all bacteria that

An archaeal species, taken near a hydrothermal vent, survives and even multiplies at 121°C.This indicates that at least some members of this group can live under severe conditions.Which of the following does not characterize the archaea?

Which statement about Gram-positive bacteria is true?

Studying Life

Small Molecules and the Chemistry of Life

Proteins, Carbohydrates, and Lipids

Nucleic Acids and the Origin of Life

Cells: the Working Units of Life

Cell Membranes

Cell Communication and Multicellularity

Energy, Enzymes, and Metabolism

Pathways That Harvest Chemical Energy

Photosynthesis: Energy From Sunlight

The Cell Cycle and Cell Division

Inheritance, Genes, and Chromosomes

Dna and Its Role in Heredity

From Dna to Protein: Gene Expression

Gene Mutation and Molecular Medicine

Regulation of Gene Expression

Genomes

Recombinant Dna and Biotechnology

Mechanisms of Evolution

Reconstructing and Using Phylogenies

Speciation

Evolution of Genes and Genomes

The History of Life on Earth

The Origin and Diversification of Eukaryotes

Plants Without Seeds: From Water to Land

The Evolution of Seed Plants

The Evolution and Diversity of Fungi

Animal Origins and the Evolution of Body Plans

Protostome Animals

Deuterostome Animals

The Plant Body

Transport in Plants

Plant Nutrition

Regulation of Plant Growth

Reproduction in Flowering Plants

Plant Responses to Environmental Challenges

Physiology, Homeostasis, and Temperature Regulation

Animal Hormones

Immunology: Animal Defense Systems

Animal Reproduction

Animal Development

Neurons, Glia, and Nervous Systems

Sensory Systems

The Mammalian Nervous System: Structure and Higher Functions

Musculoskeletal Systems

Gas Exchange

Circulatory Systems

Nutrition, Digestion, and Absorption

Salt and Water Balance and Nitrogen Excretion

Animal Behavior

The Physical Environment and Biogeography of Life

Populations

Species Interactions

Communities

Ecosystems

A Changing Biosphere

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