MCB 3023 EXAM 4 QUESTIONS WITH VERIFIED ANSWERS
d - Answers - 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.
c - Answers - Lichens DO NOT form from endosymbiotic:
a. a) plant and bacterial cells
b. b) algal and fungal cells
c. c) plant and algal cells
d. d) fungal and cyanobacterial cells
e. e) all are correct choices
c - Answers - When a mutualistic organism acquires virulence factors, it will be
recognised as a:
a. a) mutualist
b. b) commensal
c. c) parasite
d. d) endosymbiont
e. e) ectosymbiont
c - Answers - 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.
d - Answers - 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.
c - Answers - 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
,b - Answers - Once rhizobia enter the plant cell through the infection thread they
undergo rapid multiplica-tion and differentiation into pleomorphic nitrogen fixing cells
called _____ .
a) shizonts
b) bacteroids
c) elementary bodies
d) reticulate forms
e) nitromorphs
a - Answers - The host-range specificity pairing specific legumes with specific rhizobia
involves the tran-scriptional inactivation of the bacterial nod genes through the secretion
of specific ___________ by the plant.
a) flavonoids
bNod factors
c) luteolins
d) genisteins
e) lactones
e - Answers - In order to make sufficient ATP for symbiotic nitrogen fixation, the plant
supplies the symbi-onts with ____________ for energy production.
a) NADH
b) glucose
c) C3 acids
d) fatty acids
e) C4-dicarboxylic acids
e - Answers - Which of these is not able to be detected by bacterial NodD protein?
a. a) genistein
b. b) luteolin
c. c) flavonoid
d. d) C4-dicarboxylic acid
e. e) All can be detected
d - Answers - Select the incorrectly paired association:
a. a) genistein, Bradyrhizobium
b. b) luteolin,Sinorhizobium
c. c) flavonoid, nitrogen-fixing genera
d. d) luteolin, Bradyrhizobium
e. e) all are correct associations
b - Answers - Select the choice with the chronologically correct sequence of events
occurring in nodule formation:
a. a) root hair curls, bacterium attaches to root hair, infection thread forms, bacteria
proliferate and move up infection thread
,b. b) bacterium attaches to root hair, root hair curls, infection thread forms, bacteria
proliferate and move up infection thread
c. c) bacteria proliferate and move up infection thread, root hair curls, bacterium at-
taches to root hair, infection thread forms
d. d) bacterium attached to root hair, infection thread forms, bacteria proliferate and
move up infection thread, root hair curls,
e. e) infection thread forms, bacteria proliferate and move up infection thread, root hair
curls, bacterium attaches to root hair
d - Answers - Select the choice describing the earliest event in the endosymbiosis
between plants and ni-trogen-fixing bacteroids:
a. a) bacteroids release ammonium and amino acids to plants
b. b) plant TCA cycle releases C4-dicarboxylic acids to bacteroid
c. c) bacterial cells differentiate into bacteroids
d. d) bacteria move up infection thread
e. e) infection thread enters root cortex
b - Answers - Select the choice describing the latest event in the endosymbiosis
between plants and nitro-gen-fixing bacteroids:
a. a) plants secrete flavonoids to permit their recognition by specific bacterial species
b. b) plant TCA cycle releases C4-dicarboxylic acids to bacteroid
c. c) bacterial cells differentiate into bacteroids
d. d) root hairs exhibit curling
e. e) infection thread enters root cortex
b - Answers - Which genes are responsible for nitrogen fixation?
a. a) nod genes
b. b) nif genes
c. c) fix genes
d. d) luteolin genes
e. e) leghemoglobin genes
c - Answers - 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.
d - Answers - 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
, b - Answers - 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
c - Answers - 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.
d - Answers - 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
a - Answers - Flossing and brushing achieve which of the following?
a. a) Removal of viridans bacteria from tooth and gum surfaces
b. b) maintenance of an anaerobic environment for Streptococcus growth
c. c) maintenance of an anaerobic environment for Fusobacterium growth
d. d) aeration of the environment for Fusobacterium growth
e. e) increase of nutrients within the oral cavity
c - Answers - Examine this diagram showing biofilm development on the tooth surface.
Biochemically and perhaps theoretically, the application of which enzyme might reduce
colonization?
a. a) Cellulase
b. b) Amylase
c. c) Protease
d. d) Lipase
e. e) Nuclease
a - Answers - Which pathogen has the greatest potential to cause intestinal disease due
to its resilience in the face of hostile conditions?
a. a) Shigella
b. b) Vibrio
c. c) Pathogenic E. coli
d. d) Lactobacillus
e. e) Bifidobacterium
d - Answers - 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.
c - Answers - Lichens DO NOT form from endosymbiotic:
a. a) plant and bacterial cells
b. b) algal and fungal cells
c. c) plant and algal cells
d. d) fungal and cyanobacterial cells
e. e) all are correct choices
c - Answers - When a mutualistic organism acquires virulence factors, it will be
recognised as a:
a. a) mutualist
b. b) commensal
c. c) parasite
d. d) endosymbiont
e. e) ectosymbiont
c - Answers - 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.
d - Answers - 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.
c - Answers - 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
,b - Answers - Once rhizobia enter the plant cell through the infection thread they
undergo rapid multiplica-tion and differentiation into pleomorphic nitrogen fixing cells
called _____ .
a) shizonts
b) bacteroids
c) elementary bodies
d) reticulate forms
e) nitromorphs
a - Answers - The host-range specificity pairing specific legumes with specific rhizobia
involves the tran-scriptional inactivation of the bacterial nod genes through the secretion
of specific ___________ by the plant.
a) flavonoids
bNod factors
c) luteolins
d) genisteins
e) lactones
e - Answers - In order to make sufficient ATP for symbiotic nitrogen fixation, the plant
supplies the symbi-onts with ____________ for energy production.
a) NADH
b) glucose
c) C3 acids
d) fatty acids
e) C4-dicarboxylic acids
e - Answers - Which of these is not able to be detected by bacterial NodD protein?
a. a) genistein
b. b) luteolin
c. c) flavonoid
d. d) C4-dicarboxylic acid
e. e) All can be detected
d - Answers - Select the incorrectly paired association:
a. a) genistein, Bradyrhizobium
b. b) luteolin,Sinorhizobium
c. c) flavonoid, nitrogen-fixing genera
d. d) luteolin, Bradyrhizobium
e. e) all are correct associations
b - Answers - Select the choice with the chronologically correct sequence of events
occurring in nodule formation:
a. a) root hair curls, bacterium attaches to root hair, infection thread forms, bacteria
proliferate and move up infection thread
,b. b) bacterium attaches to root hair, root hair curls, infection thread forms, bacteria
proliferate and move up infection thread
c. c) bacteria proliferate and move up infection thread, root hair curls, bacterium at-
taches to root hair, infection thread forms
d. d) bacterium attached to root hair, infection thread forms, bacteria proliferate and
move up infection thread, root hair curls,
e. e) infection thread forms, bacteria proliferate and move up infection thread, root hair
curls, bacterium attaches to root hair
d - Answers - Select the choice describing the earliest event in the endosymbiosis
between plants and ni-trogen-fixing bacteroids:
a. a) bacteroids release ammonium and amino acids to plants
b. b) plant TCA cycle releases C4-dicarboxylic acids to bacteroid
c. c) bacterial cells differentiate into bacteroids
d. d) bacteria move up infection thread
e. e) infection thread enters root cortex
b - Answers - Select the choice describing the latest event in the endosymbiosis
between plants and nitro-gen-fixing bacteroids:
a. a) plants secrete flavonoids to permit their recognition by specific bacterial species
b. b) plant TCA cycle releases C4-dicarboxylic acids to bacteroid
c. c) bacterial cells differentiate into bacteroids
d. d) root hairs exhibit curling
e. e) infection thread enters root cortex
b - Answers - Which genes are responsible for nitrogen fixation?
a. a) nod genes
b. b) nif genes
c. c) fix genes
d. d) luteolin genes
e. e) leghemoglobin genes
c - Answers - 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.
d - Answers - 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
, b - Answers - 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
c - Answers - 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.
d - Answers - 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
a - Answers - Flossing and brushing achieve which of the following?
a. a) Removal of viridans bacteria from tooth and gum surfaces
b. b) maintenance of an anaerobic environment for Streptococcus growth
c. c) maintenance of an anaerobic environment for Fusobacterium growth
d. d) aeration of the environment for Fusobacterium growth
e. e) increase of nutrients within the oral cavity
c - Answers - Examine this diagram showing biofilm development on the tooth surface.
Biochemically and perhaps theoretically, the application of which enzyme might reduce
colonization?
a. a) Cellulase
b. b) Amylase
c. c) Protease
d. d) Lipase
e. e) Nuclease
a - Answers - Which pathogen has the greatest potential to cause intestinal disease due
to its resilience in the face of hostile conditions?
a. a) Shigella
b. b) Vibrio
c. c) Pathogenic E. coli
d. d) Lactobacillus
e. e) Bifidobacterium
