Question 1

Bacterial symbionts most often provide marine invertebrates in hydrothermal vents with

Accepted Answer

A)  fixed nitrogen in the form of ammonia. 
B)  sulfate and other sulfur compounds. 
C)  cellulolytic enzymes to help digest plant material. 
D)  fixed carbon dioxide in the form of organic compounds. 
A)  fixed nitrogen in the form of ammonia. 
B)  sulfate and other sulfur compounds. 
C)  cellulolytic enzymes to help digest plant material. 
D)  fixed carbon dioxide in the form of organic compounds.

Question 2

Photorhabdus is a bacterial symbiont of insect nematodes.

Accepted Answer

A) True 
 B)False

Question 3

Which of the following is TRUE of Riftia tube worm symbionts?

Accepted Answer

A)  they have never been maintained in laboratory culture 
B)  they are obligate symbionts 
C)  they have a free-living stage 
D)  they have an unusually small genome, even for a symbiont 
A)  they have never been maintained in laboratory culture 
B)  they are obligate symbionts 
C)  they have a free-living stage 
D)  they have an unusually small genome, even for a symbiont

Question 4

The function of leghemoglobin in root nodules is to

Accepted Answer

A)  bind oxygen. 
B)  chelate iron. 
C)  produce iron. 
D)  produce nitrogen. 
A)  bind oxygen. 
B)  chelate iron. 
C)  produce iron. 
D)  produce nitrogen.

Question 5

Fungi and protists serve an important role in the anaerobic digestion of cellulose in ruminants.

Accepted Answer

A) True 
 B)False

Question 6

Bacteroids are rarely found within plant cells.

Accepted Answer

A) True 
 B)False

Question 7

Coral bleaching is primarily caused by antimicrobials that disrupt the mutualistic relationships formed between corals and their bacterial symbionts.

Accepted Answer

A) True 
 B)False

Question 8

In mycorrhizal mutualisms between plants roots and fungi

Accepted Answer

A)  the plant supplies carbohydrates to the fungus and the fungus supplies phosphorus and nitrogen to the plant. 
B)  the plant supplies water to the fungus and the fungus supplies essential amino acids to the plant. 
C)  the plant protects the fungus from predation and the fungus supplies carbohydrates to the plant. 
D)  the fungus infects the plant roots, stimulating plant growth through myc factors that act as growth hormones in the plant. 
A)  the plant supplies carbohydrates to the fungus and the fungus supplies phosphorus and nitrogen to the plant. 
B)  the plant supplies water to the fungus and the fungus supplies essential amino acids to the plant. 
C)  the plant protects the fungus from predation and the fungus supplies carbohydrates to the plant. 
D)  the fungus infects the plant roots, stimulating plant growth through myc factors that act as growth hormones in the plant.

Question 9

Where are ectomycorrhizae most highly developed?

Accepted Answer

A)  boreal and temperate forests 
B)  tundra 
C)  tropical dry forests 
D)  tropical rain forests 
A)  boreal and temperate forests 
B)  tundra 
C)  tropical dry forests 
D)  tropical rain forests

Question 10

Aliivibrio fischeri symbionts benefit the Hawaiian bobtail squid by

Accepted Answer

A)  mimicking the light of the moon, which helps the squid avoid nocturnal predators. 
B)  providing essential amino acids missing from the squidʹs diet. 
C)  degrading the cellulosic cell walls of the phytoplankton the squid eats. 
D)  providing essential amino acids missing from the squidʹs diet and degrading the cellulosic cell walls of the phytoplankton the squid eats. 
A)  mimicking the light of the moon, which helps the squid avoid nocturnal predators. 
B)  providing essential amino acids missing from the squidʹs diet. 
C)  degrading the cellulosic cell walls of the phytoplankton the squid eats. 
D)  providing essential amino acids missing from the squidʹs diet and degrading the cellulosic cell walls of the phytoplankton the squid eats.

Question 11

Due to the close interactions with their hosts, obligate symbionts generally have larger genome sizes compared to other non-symbiotic bacteria.

Accepted Answer

A) True 
 B)False

Question 12

Aphids that feed on carbohydrate-rich but nutrient-poor foods obtain ________ from their endosymbiotic bacterial partners.

Accepted Answer

A)  ATP 
B)  amino acids 
C)  ammonium 
D)  volatile fatty acids 
A)  ATP 
B)  amino acids 
C)  ammonium 
D)  volatile fatty acids

Question 13

The fungal division containing arbuscular mycorrhizae is the

Accepted Answer

A)  Betaproteobacteria. 
B)  Basidiomycota. 
C)  Glomerulomycota. 
D)  Rhizobia. 
A)  Betaproteobacteria. 
B)  Basidiomycota. 
C)  Glomerulomycota. 
D)  Rhizobia.

Question 14

Genome sequencing of the bacterial symbionts of animals has allowed us to compare the genomic features of several symbionts. The following data was collected on two insect symbionts:
Symbiont A: 0.4 Mb genome, 20% G+C content, missing or incomplete peptidoglycan synthesis and nucleotide synthesis pathways.
Symbiont B: 1.8 Mb genome, 40% G+C content, peptidoglycan and most nucleotide synthesis pathways complete.
What can you deduce about these two insect symbionts based on their genomes?

Accepted Answer

Symbiont A is likely a vertically transf

Question 15

Plant root nodules are

Accepted Answer

A)  formed from gall-rotting bacteria that decompose plant roots. 
B)  harmful to plants, because the bacteria outcompete the plants for nutrients. 
C)  sites where nitrogen fixation occurs. 
D)  structures created by fungi and are found in all agricultural crops. 
A)  formed from gall-rotting bacteria that decompose plant roots. 
B)  harmful to plants, because the bacteria outcompete the plants for nutrients. 
C)  sites where nitrogen fixation occurs. 
D)  structures created by fungi and are found in all agricultural crops.

Question 16

Horizontal gene transfer between insects and their symbionts

Accepted Answer

A)  happens frequently because of coevolution. 
B)  causes genome reduction in the symbiont and genome expansion in the host. 
C)  causes genome reduction in both the host and the symbiont. 
D)  has been observed, but is considered a rare event. 
A)  happens frequently because of coevolution. 
B)  causes genome reduction in the symbiont and genome expansion in the host. 
C)  causes genome reduction in both the host and the symbiont. 
D)  has been observed, but is considered a rare event.

Question 17

Which of the following is a common feature of primary insect symbionts?

Accepted Answer

A)  accelerated mutation rates only 
B)  extreme genome reduction only 
C)  high A+T content only 
D)  accelerated mutation rates, extreme genome reduction, and high A+T content 
A)  accelerated mutation rates only 
B)  extreme genome reduction only 
C)  high A+T content only 
D)  accelerated mutation rates, extreme genome reduction, and high A+T content

Question 18

Myc factors are

Accepted Answer

A)  a type of strigolactone hormone. 
B)  lipochitin oligosaccharide signaling proteins produced by arbuscular mycorrhizae. 
C)  examples of chemicals that mycorrhizae obtain from the soil. 
D)  Carbohydrate structures that form connections between mycorrhizae and plants. 
A)  a type of strigolactone hormone. 
B)  lipochitin oligosaccharide signaling proteins produced by arbuscular mycorrhizae. 
C)  examples of chemicals that mycorrhizae obtain from the soil. 
D)  Carbohydrate structures that form connections between mycorrhizae and plants.

Question 19

How are symbiotic relationships important in agriculture and food production? Use at least two different examples to support your answer and explain how understanding these symbioses could help produce more food.

Accepted Answer

Answers can use any two of the following

Question 20

Fibrobacteres comprise the greatest proportion of the bacterial species in ruminant guts.

Accepted Answer

A) True 
 B)False

Exam 23: Microbial Symbioses

Bacterial symbionts most often provide marine invertebrates in hydrothermal vents with

Photorhabdus is a bacterial symbiont of insect nematodes.

Which of the following is TRUE of Riftia tube worm symbionts?

The function of leghemoglobin in root nodules is to

Fungi and protists serve an important role in the anaerobic digestion of cellulose in ruminants.

Bacteroids are rarely found within plant cells.

Coral bleaching is primarily caused by antimicrobials that disrupt the mutualistic relationships formed between corals and their bacterial symbionts.

In mycorrhizal mutualisms between plants roots and fungi

Where are ectomycorrhizae most highly developed?

Aliivibrio fischeri symbionts benefit the Hawaiian bobtail squid by

Due to the close interactions with their hosts, obligate symbionts generally have larger genome sizes compared to other non-symbiotic bacteria.

Aphids that feed on carbohydrate-rich but nutrient-poor foods obtain ________ from their endosymbiotic bacterial partners.

The fungal division containing arbuscular mycorrhizae is the

Plant root nodules are

Horizontal gene transfer between insects and their symbionts

Which of the following is a common feature of primary insect symbionts?

Myc factors are

How are symbiotic relationships important in agriculture and food production? Use at least two different examples to support your answer and explain how understanding these symbioses could help produce more food.

Fibrobacteres comprise the greatest proportion of the bacterial species in ruminant guts.

The Microbial World

Microbial Cell Structure and Function

Microbial Metabolism

Molecular Information Flow and Protein Processing

Microbial Growth and Its Control

Microbial Regulatory Systems

Molecular Biology of Microbial Growth

Viruses and Their Replication

Microbial Systems Biology

Viral Genomics, Diversity, and Ecology

Genetics of Bacteria and Archaea

Biotechnology and Synthetic Biology

Microbial Evolution and Systematics

Metabolic Diversity of Microorganisms

Functional Diversity of Microorganisms

Diversity of Bacteria

Diversity of Archaea

Diversity of Microbial Eukarya

Taking the Measure of Microbial Systems

Microbial Ecosystems

Nutrient Cycles

Microbiology of the Built Environment

Microbial Symbioses with Humans

Microbial Infection and Pathogenesis

Innate Immunity: Broadly Specific Host Defenses

Adaptive Immunity: Highly Specific Host Defenses

Clinical Microbiology and Immunology

Epidemiology

Person-to-Person Bacterial and Viral Diseases

Vectorborne and Soilborne Bacterial and Viral Diseases

Waterborne and Foodborne Bacterial and Viral Diseases

Eukaryotic Pathogens: Fungi, Protozoans, and Helminths

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