Question 1

Microbial symbionts are horizontally transferred by parental cells directly passing on the symbionts during meiosis.

Accepted Answer

A) True 
 B)False  False

Question 2

Which of the following do dinoflagellates most commonly associate with in a mutualistic relationship?

Accepted Answer

A) clams 
B) corals 
C) flatworms 
D) snails 
A) clams 
B) corals 
C) flatworms 
D) snails B

Question 3

What percentage of terrestrial plants are colonized by arbuscular mycorrhizae?

Accepted Answer

A) 10 
B) 25 
C) 50 
D) 85 
A) 10 
B) 25 
C) 50 
D) 85 D

Question 4

While rhizobia usually associate with plant roots,nodules can also be formed along the stems of leguminous plants.

Accepted Answer

A) True 
 B)False

Question 5

What is coral bleaching and how might corals be able to adapt to avoid the destruction of coral reefs?

Accepted Answer

Coral bleaching occurs when the phototro

Question 6

Obligately symbiotic relationships generally do not foster horizontal gene transfer at a higher rate than non-symbiotic relationships.

Accepted Answer

A) True 
 B)False

Question 7

Bacterial symbionts most often provide marine invertebrates with

Accepted Answer

A) fixed nitrogen in the form of ammonia. 
B) essential amino acids missing from the animal's diet. 
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) essential amino acids missing from the animal's diet. 
C) cellulolytic enzymes to help digest plant material. 
D) fixed carbon dioxide in the form of organic compounds.

Question 8

Bacterial symbionts of termite hindguts play a critical role in the termite's

Accepted Answer

A) reproduction. 
B) nitrogen metabolism. 
C) resistance to fungal infection. 
D) reproduction and nitrogen metabolism. 
A) reproduction. 
B) nitrogen metabolism. 
C) resistance to fungal infection. 
D) reproduction and nitrogen metabolism.

Question 9

What is the fate of H₂ produced within a rumen?

Accepted Answer

A) It is released via eructation (belching). 
B) It is transformed,along with other ions,into inorganic compounds. 
C) It is used in acetogenesis. 
D) It is used in methanogenesis. 
A) It is released via eructation (belching). 
B) It is transformed,along with other ions,into inorganic compounds. 
C) It is used in acetogenesis. 
D) It is used in methanogenesis.

Question 10

Which of the following is NOT a major question in the Human Microbiome Project?

Accepted Answer

A) Are differences in the relative abundance of different bacteria important? 
B) Do differences in the human microbiome correlate with differences in human health? 
C) Is there a correlation between microbial population structure and host genotype? 
D) How can we reduce the number of microbes on the human body? 
A) Are differences in the relative abundance of different bacteria important? 
B) Do differences in the human microbiome correlate with differences in human health? 
C) Is there a correlation between microbial population structure and host genotype? 
D) How can we reduce the number of microbes on the human body?

Question 11

How are root nodule and arbuscular mycorrhizal symbioses similar?

Accepted Answer

A) They both use lipochitin oligosaccharide signaling factors to initiate root colonization. 
B) They both supply nitrogen to the host plant through nitrogen fixation. 
C) They both increase absorption of nutrients from soil. 
D) They are both required for the growth and reproduction of their host plants. 
A) They both use lipochitin oligosaccharide signaling factors to initiate root colonization. 
B) They both supply nitrogen to the host plant through nitrogen fixation. 
C) They both increase absorption of nutrients from soil. 
D) They are both required for the growth and reproduction of their host plants.

Question 12

Several rhizobial species within a cross-inoculation group should be able to grow with particular legume species such as alfalfa.However,the same cross-inoculation group would be unable to associate with another legume species such as peas.

Accepted Answer

A) True 
 B)False

Question 13

How do phototrophic microorganisms benefit when associating with corals?

Accepted Answer

A) Calcium and carbonate ions are released,which help buffer the pH and prevent dramatic pH shifts. 
B) The coral skeleton is used as a source of bicarbonate for the autotrophic growth of the phototrophs. 
C) The coral skeleton is an extremely efficient light-gathering structure that greatly enhances light harvesting for photosynthesis. 
D) The water's temperature in and around the coral skeleton is much warmer. 
A) Calcium and carbonate ions are released,which help buffer the pH and prevent dramatic pH shifts. 
B) The coral skeleton is used as a source of bicarbonate for the autotrophic growth of the phototrophs. 
C) The coral skeleton is an extremely efficient light-gathering structure that greatly enhances light harvesting for photosynthesis. 
D) The water's temperature in and around the coral skeleton is much warmer.

Question 14

Both pathogenic bacteria and primary symbionts have a tendency to lose genes for catabolic pathways.

Accepted Answer

A) True 
 B)False

Question 15

Gut symbionts are lost after each molting a termite undergoes.

Accepted Answer

A) True 
 B)False

Question 16

Molecular evidence suggests that leeches contain two distinct bacterial communities in their bladder.

Accepted Answer

A) True 
 B)False

Question 17

Why do obligate symbionts often contain lower G+C content when compared to free-living organisms?

Accepted Answer

A) Ancestral symbionts had low GC content genomes by chance,and these low GC content genomes are passed onto their progeny. 
B) Free-living organisms must have a more stable genome to survive; low G+C content organisms are often selected against in nature. 
C) Replicating high G+C content genomes requires several additional enzymes,to break apart the strong triple bonds formed from GC pairs,which are rarely found in symbionts with relatively small genome sizes. 
D) Symbionts usually do not have as many DNA repair mechanisms as free-living organisms,and two common spontaneous mutations change GC pairs into AT pairs. 
A) Ancestral symbionts had low GC content genomes by chance,and these low GC content genomes are passed onto their progeny. 
B) Free-living organisms must have a more stable genome to survive; low G+C content organisms are often selected against in nature. 
C) Replicating high G+C content genomes requires several additional enzymes,to break apart the strong triple bonds formed from GC pairs,which are rarely found in symbionts with relatively small genome sizes. 
D) Symbionts usually do not have as many DNA repair mechanisms as free-living organisms,and two common spontaneous mutations change GC pairs into AT pairs.

Question 18

The structural and trophic foundation of coral reefs is a mutualistic relationship between

Accepted Answer

A) cyanobacteria and sponges (Porifera). 
B) chemolithotrophic bacteria and stony corals (Cnidaria). 
C) dinoflagellates and stony corals (Cnidaria). 
D) cyanobacteria and stony corals (Cnidaria). 
A) cyanobacteria and sponges (Porifera). 
B) chemolithotrophic bacteria and stony corals (Cnidaria). 
C) dinoflagellates and stony corals (Cnidaria). 
D) cyanobacteria and stony corals (Cnidaria).

Question 19

Which bacterium contains a large Ti plasmid and causes crown gall disease in plants?

Accepted Answer

A) Agrobacterium rhizogenes 
B) Agrobacterium tumefaciens 
C) Aliivibrio fischeri 
D) Butyrivibrio fibrisolvens 
A) Agrobacterium rhizogenes 
B) Agrobacterium tumefaciens 
C) Aliivibrio fischeri 
D) Butyrivibrio fibrisolvens

Question 20

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.

Exam 22: Microbial Symbioses

Microbial symbionts are horizontally transferred by parental cells directly passing on the symbionts during meiosis.

Which of the following do dinoflagellates most commonly associate with in a mutualistic relationship?

What percentage of terrestrial plants are colonized by arbuscular mycorrhizae?

While rhizobia usually associate with plant roots,nodules can also be formed along the stems of leguminous plants.

What is coral bleaching and how might corals be able to adapt to avoid the destruction of coral reefs?

Obligately symbiotic relationships generally do not foster horizontal gene transfer at a higher rate than non-symbiotic relationships.

Bacterial symbionts most often provide marine invertebrates with

Bacterial symbionts of termite hindguts play a critical role in the termite's

What is the fate of H₂ produced within a rumen?

Which of the following is NOT a major question in the Human Microbiome Project?

How are root nodule and arbuscular mycorrhizal symbioses similar?

Several rhizobial species within a cross-inoculation group should be able to grow with particular legume species such as alfalfa.However,the same cross-inoculation group would be unable to associate with another legume species such as peas.

How do phototrophic microorganisms benefit when associating with corals?

Both pathogenic bacteria and primary symbionts have a tendency to lose genes for catabolic pathways.

Gut symbionts are lost after each molting a termite undergoes.

Molecular evidence suggests that leeches contain two distinct bacterial communities in their bladder.

Why do obligate symbionts often contain lower G+C content when compared to free-living organisms?

The structural and trophic foundation of coral reefs is a mutualistic relationship between

Which bacterium contains a large Ti plasmid and causes crown gall disease in plants?

Plant root nodules are

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