Deck 17: Microbial Symbionts

Question 1

Once rhizobia enter the plant cell through the infection thread they undergo rapid multiplication and differentiation into pleomorphic nitrogen fixing cells called _____ .

A)shizonts
B)bacteroids
C)elementary bodies
D)reticulate forms
E)nitromorphs

Answer 1

B

Question 2

The most common inhabitants of the human skin are members of which phyla?

A)Proteobacteria and Bacteroidetes
B)Proteobacteria and Firmicutes
C)Bacteroidetes and Firmicutes
D)Firmicutes and Actinobacteria
E)Actinobacteria and Proteobacteria

Answer 2

D

Question 3

Which of these is the MOST abundant bacterial group in the colon?

A)members of the phylum Proteobacteria
B)the family Enterobacteriaceae
C)obligate anaerobes
D)facultative anaerobes
E)lactobacilli.

Answer 3

C

Question 4

Which genes are responsible for nitrogen fixation?

A)nod genes
B)nif genes
C)fix genes
D)luteolin genes
E)leghemoglobin genes

Question 5

The red color of plant root nodules is due to this oxygen binding protein.

A)cytochrome c
B)flavoprotein
C)leghemoglobin
D)menaquinone
E)nitrate reductase

Question 6

Lichens DO NOT form from endosymbiotic:

A)plant and bacterial cells
B)algal and fungal cells
C)plant and algal cells
D)fungal and cyanobacterial cells
E)all are correct choices

Question 7

The host-range specificity pairing specific legumes with specific rhizobia involves the transcriptional inactivation of the bacterial nod genes through the secretion of specific ___________ by the plant.

A)flavonoids
BNod factors
C)luteolins
D)genisteins
E)lactones

Question 8

The vagina of women of child-bearing age has an acidic pH.This is due to the colonization by which organisms?

A)staphylococci
B)lactobacilli
C)Candida sp
D)Bacteroides sp
E)micrococci

Question 9

Select the incorrectly paired association:

A)genistein,Bradyrhizobium
B)luteolin,Sinorhizobium
C)flavonoid,nitrogen-fixing genera
D)luteolin,Bradyrhizobium
E)all are correct associations

Question 10

In order to make sufficient ATP for symbiotic nitrogen fixation,the plant supplies the symbionts with ____________ for energy production.

A)NADH
B)glucose
C)C3 acids
D)fatty acids
E)C4-dicarboxylic acids

Question 11

Select the choice with the chronologically correct sequence of events occurring in nodule formation:

A)root hair curls,bacterium attaches to root hair,infection thread forms,bacteria proliferate and move up infection thread
B)bacterium attaches to root hair,root hair curls,infection thread forms,bacteria proliferate and move up infection thread
C)bacteria proliferate and move up infection thread,root hair curls,bacterium attaches to root hair,infection thread forms
D)bacterium attached to root hair,infection thread forms,bacteria proliferate and move up infection thread,root hair curls,
E)infection thread forms,bacteria proliferate and move up infection thread,root hair curls,bacterium attaches to root hair

Question 12

Which of these is characteristic of the nitrogenase enzyme?

A)It is found in both prokaryotes and eukaryotes.
B)It converts dinitrogen to nitrate.
C)It requires hydrogen gas for activity.
D)It is irreversibly inactivated by oxygen.
E)It is found in all plant symbionts.

Question 13

Which of these is not able to be detected by bacterial NodD protein?

A)genistein
B)luteolin
C)flavonoid
D)C4-dicarboxylic acid
E)All can be detected

Question 14

When a mutualistic organism acquires virulence factors,it will be recognised as a:

A)mutualist
B)commensal
C)parasite
D)endosymbiont
E)ectosymbiont

Question 15

What is an endophyte?

A)A parasite of a plant.
B)A parasite of an animal.
C)A symbiont that lives inside plant cells.
D)A member of the plant root rhizosphere.
E)A member of the intestinal tract microbial community.

Question 16

What is the human microbiome composed of?

A)Microbes that live in the intestinal tract of humans.
B)All the microbes that cause disease in humans.
C)All microbes that live on or within the human body.
D)Microbes that contribute to the health of humans.
E)Microbes that live on human skin.

Question 17

Which of these is true of a mutualistic relationship?

A)Neither organism benefits or is harmed by the relationship.
B)One member benefits and the other member is harmed.
C)One member benefits and the other member does not receive any benefit.
D)Both organisms benefit.
E)Both members are harmed from the relationship.

Question 18

Select the choice describing the latest event in the endosymbiosis between plants and nitrogen-fixing bacteroids:

A)plants secrete flavonoids to permit their recognition by specific bacterial species
B)plant TCA cycle releases C4-dicarboxylic acids to bacteroid
C)bacterial cells differentiate into bacteroids
D)root hairs exhibit curling
E)infection thread enters root cortex

Question 19

The majority of Archaea found in the human intestinal tract are _____ .

A)sulfate-reducing bacteria
B)halobacteria
C)sulfide oxidizing bacteria
D)methanogens
E)fermenters

Question 20

Select the choice describing the earliest event in the endosymbiosis between plants and nitrogen-fixing bacteroids:

A)bacteroids release ammonium and amino acids to plants
B)plant TCA cycle releases C4-dicarboxylic acids to bacteroid
C)bacterial cells differentiate into bacteroids
D)bacteria move up infection thread
E)infection thread enters root cortex

Question 21

The animal with the least efficient microbial intestinal fermentation system is the:

A)bear
B)guinea pig
C)mouse
D)camel
E)antelope

Question 22

Flossing and brushing achieve which of the following?

A)Removal of viridans bacteria from tooth and gum surfaces
B)maintenance of an anaerobic environment for Streptococcus growth
C)maintenance of an anaerobic environment for Fusobacterium growth
D)aeration of the environment for Fusobacterium growth
E)increase of nutrients within the oral cavity

Question 23

An example of a rumen fermenter is the:

A)horse
B)koala
C)sheep
D)rabbit
E)human

Question 24

The correct order of structures ingested grass will pass through in a ruminant is:

A)reticulum,omasum,abomasom,rumen
B)reticulum,rumen,omasum,abomasom
C)omasum,reticulum,rumen,abomasom
D)reticulum,abomasom,omasum,rumen
E)abomasom,reticulum,rumen,omasum

Question 25

The correct order of structures ingested grass will pass through in a cecal fermenter is:

A)reticulum,omasum,abomasom,rumen
B)reticulum,rumen,omasum,colon
C)stomach,small intestine,cecum,colon
D)stomach,small intestine,colon,cecum
E)abomasom,colon,rumen,cecum

Question 26

Herbivores require microorganisms to help them with the digestion of this compound.

A)starch
B)glycogen
C)cellulose
D)proteins
E)nucleic acids

Question 27

Where on the skin do you expect to find the highest proportin of phylum Firmicutes?

A)head
B)forearm
C)toes
D)equal proportions in all environments
E)none is a correct choice

Question 28

What possible inconsistency do you observe in the color coding of this diagram?

A)Small intestine plays different roles in the three fermenters but is coded the same way in each diagram
B)The stomach and abomason do not play the same digestive role
C)The stomach should be present in all three digestive types
D)Cecum and colon are always next to one another,yet their roles are sometimes classified as one,and at other times as two different fermentation steps
E)None is a possible inconsistency

Question 29

Which of these is TRUE of ruminants?

A)They possess a single stomach chamber and long cecum.
B)They are considered to be hindgut fermenters.
C)They are inefficient in the digestion of plant material.
D)They obtain nutrients from digestion carried out by rumen microorganisms.
E)They often consume their own feces.

Question 30

The correct order of structures ingested grass will pass through in a colonic fermenter is:

A)reticulum,cecum,abomasom,small intestine
B)reticulum,rumen,omasum,colon
C)stomach,small intestine,cecum,colon
D)stomach,small intestine,colon,cecum
E)abomasom,colon,stomach,cecum

Question 31

Examine this diagram showing biofilm development on the tooth surface.Biochemically and perhaps theoretically,the application of which enzyme might reduce colonization?

A)Cellulase
B)Amylase
C)Protease
D)Lipase
E)Nuclease

Question 32

Microbes in the rumen are very efficient at converting ____________ and _________ into amino acids.

A)ammonia and urea
B)glucose and pyruvate
C)starch and cellulose
D)fatty acids and acetate
E)pyruvate and lactate

Question 33

Acetogenesis is the production of acetic acid from which material(s)?

A)lactate
B)pyruvate
C)carbon dioxide and hydrogen
D)oxaloacetate
E)glucose

Question 34

Many of the rumen bacteria specialize in the breakdown of these macromolecules.

A)proteins
B)cellulose polymers
C)peptidoglycans
D)nucleic acids
E)fatty acids

Question 35

Which pathogen has the greatest potential to cause intestinal disease due to its resilience in the face of hostile conditions?

A)Shigella
B)Vibrio
C)Pathogenic E.coli
D)Lactobacillus
E)Bifidobacterium

Question 36

Which of these structures possesses a role in digestion not observed in all three fermentive types (colonic,cecal,ruminant)?

A)rumen
B)Cecum
C)Reticulum
D)Abomasom
E)Colon

Question 37

Some herbivorous cecal fermenters obtain additional nutrients from their food sources by this method.

A)Regurgitating their food and chewing it again.
B)Retaining it in their large intestine for long periods of time.
C)Eating their feces.
D)Selectively eating certain plants.
E)Moving the cecal-digested food back to the small intestine for absorption.

Question 38

When the diet of a ruminant is drastically changed from grass to a starch rich diet,the ruminant may become very ill or die because:

A)the microbes in the rumen cannot break down starch.
B)of the production of large amounts of acid,resulting in acidosis.
C)they lack a source of protein.
D)they are unable to regurgitate the starch as cud.
E)the starch is broken down very slowly and the rumen becomes clogged.

Question 39

Which microbe has the greatest potential to colonize the stomach?

A)Shigella
B)Helicobacter
C)Pathogenic E.coli
D)Lactobacillus
E)Bifidobacterium

Question 40

Helicobacter survives in the stomach because it is:

A)An acidophile
B)An alkaliphile
C)Capable of raising pH in its local niche
D)Capable of lowering pH in its local niche
E)Encapsulated and protected by intestinal mucus

Question 41

Which of these contains zooxanthellae as photosynthetic symbionts?

A)shipworms
B)termites
C)lichens
D)coral
E)tubeworms

Question 42

Cellulose consumed by the lower termite is hydrolyzed by cellulases produced by _____ .

A)fungi
B)bacteria
C)archaeons
D)the termite
E)yeast

Question 43

The shipworm endosymbiont Teredinibacter turneri is of commercial potential because of its combined activities of::

A)Nitrification and cellulolysis
B)Denitrification and cellulolysis
C)Nitrification and amylase hydrolysis
D)Denitrification and amylase hydrolysis
E)Denitrification and high temperature proteolysis

Question 44

Helicobacter pylori is now known to cause stomach and duodenal ulcers.Marshall's drastic experimental ingestion of this microbe was required to prove beyond doubt that this was the causative agent.Why do you imagine that his experiment was necessary? (Select all that apply)

A)The hostile stomach pH was regarded as a sterile environment
B)Prevailing medical opinion was that stomach ulcers were caused by viruses
C)Cause and effect in pathogenesis always requires human experimentation
D)Antibiotic therapies had been tried in the past and shown ineffective
E)Medical opinion related ulcers to stress,diet and smoking

Question 45

The hydrogen and carbon dioxide produced in the gut of the lower termite are used to produce __________ by symbiotic microbes.

A)methane
B)lactate
C)fatty acids
D)amino acids
E)glucose

Question 46

Which of these is NOT a negative influence on coral symbosis?

A)Increasing temperatures of ocean waters
B)Algal ingestion from ocean waters
C)Freshwater runoff into reef environments
D)Alterations in ultraviolet light intensity
E)Changing pH of ocean waters

Question 47

Lower termites feed primarily on wood and contain symbiotic:

A)bacteria in their intestine.
B)bacteria and archaeons in their intestine.
C)fungi in their intestine.
D)protozoa,bacteria,and archaeons in their intestine.
E)protozoa and fungi in their intestine.

Question 48

If lower termites are fed antibiotics they cannot survive because:

A)Their cellulase-producing bacterial endosymbionts are killed
B)Their cellulase-producing protozoan endosymbionts are killed
C)Their nitrogenous compound-providing bacterial endosymbionts are killed
D)Their nitrogenous compound-providing protozoan endosymbionts are killed
E)The methanogens in the termite intestine are killed

Question 49

In which of the following animals would you expect to find the longest ratio of small intestine to large intestine?

A)Antelope
B)Hawk
C)Finch
D)Buffalo
E)All would be of equal relative length

Question 50

How do termites obtain nitrogen in their diet?

A)From digestion of proteins.
B)From digestion of nucleic acids.
C)From nitrogen fixing bacteria in their gut.
D)From urea.
E)From nitrogen fixing protozoa.

Question 51

How do primary endosymbionts of insects differ from secondary endosymbionts?

A)Primary endosymbionts provide the insect with nutrients.
B)Secondary endosymbionts protect the insect from harmful bacteria.
C)Secondary endosymbionts do not remain with the host after three or four generations.
D)Primary endosymbionts show evidence of co-speciation with the host insect.
E)Secondary endosymbionts can easily be cultured.

Question 52

Scientist are able to make an insect symbiont free by this method.

A)Hatching insect eggs in a sterile environment.
B)Treating the insect with an antibiotic.
C)Mating the insect with a symbiont free insect.
D)Irradiating insect eggs.
E)Putting the insect on a different diet.

Question 53

Which of the following is NOT a feature of a primary endosymbiont?

A)They all have reduced genomes.
B)They are found in specialized cells called bacteriocytes.
C)Their genome sequence shows a high degree of conservation
D)They are passed on maternally.
E)They are required for survival or fertility.

Question 54

Which part of the lichen provides photosynthetic capability? (Select all that apply)

A)photobiont
B)mycobiont
C)fungal cells
D)algal cells
E)cyanobacterial cells

Question 55

The bacterial genus ___________ is a secondary symbiont and is capable of changing the female to male ratio of an insect to primarily female.

A)Rickettsia
B)Wolbachia
C)Pseudomonas
D)Culex
E)Bordetella

Question 56

Which of these enzymes,isolable from shipworm endosymbionts,shows commercial potential?

A)Amylase
B)Protease
C)Lipase
D)Nuclease
E)Cellulase

Question 57

Dry areas of the skin such as the inner forearm are seen to contain the most diverse populations of microbes.Suggest a reason why this is observed: (Select all that apply)

A)Increased exposure to atmospheric microbes which may vary with geographical location
B)Maximum oil production occurs in this region
C)A mix of hair,sweat and sebaceous gland environments exist here
D)The environment is less salty than others on the skin
E)All are plausible explanations for the observation

Question 58

Most microbe-host relationships are harmful.

Question 59

Most microbial symbionts of invertebrates are in this group.

A)yeast
B)Archaea
C)protozoa
D)algae
E)Bacteria

Question 60

Amino acids for anabolic requirements are obtained by ruminants through: (Select all that apply)

A)ingestion of plant proteins
B)ingestion of animal proteins
C)digestion of microbial proteins
D)digestion of microbially-converted nitrogenous wastes
E)kidney reabsorption of urea

Question 61

Hindgut fermenters have greater fermentation efficiency than ruminants.

Question 62

Most endosymbionts of invertebrates can easily be cultured.

Question 63

A group of microorganisms that are interdependent on one another for the stability of the community is called a/an__________________

Question 64

All microorganisms that live on or within the human body are referred to collectively as the human ________________.

Question 65

Intestinal microorganisms are important for the proper functioning of the immune system.

Question 66

Plaque on human teeth is considered a biofilm.

Question 67

The type of symbiotic relationship in which one member benefits and the other member is not affected is called _________________.