levinson questions Flashcards
1: Each of the following statements concerning the surface structures of bacteria is correct except:
A: Pili mediate the interaction of bacteria with mucosal epithelium
B: Polysaccharide capsules retard phagocytosis
C: Both gram-negative rods and cocci have lipopolysaccharide (“endotoxin”) in their cell wall
D: bacterial flagella are nonantigenic in humans because they closely resemble human flagella in chemical composition
D
2: each of the following statements concerning peptidoglycan is correct except:
A: it has a backbone composed of alternating units of muramic acid and acetylglucosamine
B: cross-links between the tetrapeptides involved D-alanine
C: it is thinner in gram-positive than in gram-negative cells
D: it can be degraded by lysozyme
C
3: each of the following statements concerning bacterial spores is correct except:
A: their survival ability is based on their enhanced metabolic activity
B: they are formed by gram-positive rods
C: they can be killed by being heated to 121 degrees for 15 minutes
D: they are formed primarily when nutrients are limited
A
16: the identification of bacteria by serologic tests is based on the presence of specific antigens. which on of the following bacterial components is least likely to contain useful antigens?
A: capsule
B: flagella
C: exotoxins
D: ribosomes
D
20: each of the following statements concerning the gram stain is correct except:
A: escherichia coli stains pink because it has a thin peptidoglycan layer
B: streptococcus pyogenes stains blue because it has a thick peptidoglycan layer
C: mycobacterium tuberculosis stains blue because it has a thick lipid layer
D: mycoplasma pneumoniae is not visible in the gram stain because it does not have a cell wall
C
22: in the gram stain, the decolorization of gram-negative bacteria by alcohol is most closely related to:
A: proteins encoded by F plasmids
B: lipids in the cell walls
C: 70S ribosomes
D: branched polysaccharides in the capsule
B
26: bacterial surface structures that show antigenic diversity include each of the following except:
A: pili
B: capsules
C: flagella
D: peptidoglycan
D
37: each of the following statements concerning the structure and chemical composition of bacteria is correct except:
A: some gram-positive cocci contain teichoic acid external to the peptidoglycan
B: some gram-positive rods produce spores that are resistant to boiling
C: some gram-negative rods contain lipid A in their outer cell membrane
D: some mycoplasms contain pentaglycine in their peptidoglycan
D
each set of matching question in this section consists of a list of lettered options followed by several numbered items. for each numbered item, select the one lettered option that is most closely associated with it.
A: capsule B: periplasmic space C: peptidoglycan D: lipid A E: 30S ribosomal subunit F: G protein G: Pilus H: ADP-ribosyliating enzyme I: mesosome J: Flagellum K: transposon
536: is the site of action of lysozyme
C
each set of matching question in this section consists of a list of lettered options followed by several numbered items. for each numbered item, select the one lettered option that is most closely associated with it.
A: capsule B: periplasmic space C: peptidoglycan D: lipid A E: 30S ribosomal subunit F: G protein G: Pilus H: ADP-ribosyliating enzyme I: mesosome J: Flagellum K: transposon
537: mediates adherence of bacteria to mucous membranes
G
each set of matching question in this section consists of a list of lettered options followed by several numbered items. for each numbered item, select the one lettered option that is most closely associated with it.
A: capsule B: periplasmic space C: peptidoglycan D: lipid A E: 30S ribosomal subunit F: G protein G: Pilus H: ADP-ribosyliating enzyme I: mesosome J: Flagellum K: transposon
538: is the toxic component of endotoxin
D
block two, 4: regarding the gram stain, which one of the following is the most accurate?
A: after adding the crystal violet and gram’s iodine, both gram-positive bacteria and gram-negative bacteria will appear blue
B: if you forget to stain with the red dye (safranin or basic fuchin), both gram-positive bacteria and gram-negative bacteria will appear blue
C: if you forget to heat-fix, both gram-positive bacteria and gram-negative bacteria will appear blue
D: one reason why bacteria have a different color in this stain is because the gram-positive bacteria have lipid in their membrane, whereas gram-negative do not
A
block two, 8: regarding bacterial spores, which one of the following is the most accurate?
A: one spore germinates to form one bacterium
B: they are produced primarily within human red blood cells
C: they are killed by boiling by at sea level but not high altitude
D: they are produced by anaerobes only in the presence of oxygen
E: they contain endotoxin, which accounts for their ability to cause disease
A
27: the effects of antibody on bacteria include each of the following except:
A: lysis of gram-negative bacteria in conjunction with complement
B: augmentation of phagocytosis
C: increase in the frequency of lysogeny
D: inhibition of adherence of bacteria to mucosal surfaces
C
19: each of the following is a typical property of obligate anaerobes except:
A: they generate energy by using the cytochrome system
B: the grow best in the absence of air
C: They lack superoxide dismutase
D: the lack catalase
A
29: each of the following statements concerning bacterial and human cells is correct except:
A: bacteria are prokaryotic (i.e. they have one molecule of DNA, are haploid, and have no nuclear membrane), whereas human cells are eukaryotic (i.e. they have multiple chromosomes, are diploid, and have a nuclear membrane)
B: bacteria derive their energy by oxidative phosphorylation within mitochondria in a manner similar to human cells
C: bacterial and human ribosomes are of different sizes and chemical compositions
D: bacterial cells possess peptidoglycan, whereas human cells do not
B
