Levinson Q's

Question 2

1: Each of the following statements concerning the surface structures of bacteria is correct except:A: Pili mediate the interaction of bacteria with mucosal epitheliumB: Polysaccharide capsules retard phagocytosisC: Both gram-negative rods and cocci have lipopolysaccharide (“endotoxin”) in their cell wallD: bacterial flagella are nonantigenic in humans because they closely resemble human flagella in chemical composition

Answer 2

D

Question 3

2: each of the following statements concerning peptidoglycan is correct except:A: it has a backbone composed of alternating units of muramic acid and acetylglucosamineB: cross-links between the tetrapeptides involved D-alanineC: it is thinner in gram-positive than in gram-negative cellsD: it can be degraded by lysozyme

Answer 3

C

Question 4

3: each of the following statements concerning bacterial spores is correct except:A: their survival ability is based on their enhanced metabolic activityB: they are formed by gram-positive rodsC: they can be killed by being heated to 121 degrees for 15 minutesD: they are formed primarily when nutrients are limited

Answer 4

A

Question 5

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: capsuleB: flagellaC: exotoxinsD: ribosomes

Answer 5

D

Question 6

20: each of the following statements concerning the gram stain is correct except:A: escherichia coli stains pink because it has a thin peptidoglycan layerB: streptococcus pyogenes stains blue because it has a thick peptidoglycan layerC: mycobacterium tuberculosis stains blue because it has a thick lipid layerD: mycoplasma pneumoniae is not visible in the gram stain because it does not have a cell wall

Answer 6

C

Question 7

22: in the gram stain, the decolorization of gram-negative bacteria by alcohol is most closely related to:A: proteins encoded by F plasmidsB: lipids in the cell wallsC: 70S ribosomesD: branched polysaccharides in the capsule

Answer 7

B

Question 8

26: bacterial surface structures that show antigenic diversity include each of the following except:A: piliB: capsulesC: flagellaD: peptidoglycan

Answer 8

D

Question 9

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 peptidoglycanB: some gram-positive rods produce spores that are resistant to boilingC: some gram-negative rods contain lipid A in their outer cell membraneD: some mycoplasms contain pentaglycine in their peptidoglycan

Answer 9

D

Question 10

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: capsuleB: periplasmic spaceC: peptidoglycanD: lipid AE: 30S ribosomal subunitF: G proteinG: PilusH: ADP-ribosyliating enzymeI: mesosomeJ: FlagellumK: transposon536: is the site of action lysozyme

Answer 10

C

Question 11

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: capsuleB: periplasmic spaceC: peptidoglycanD: lipid AE: 30S ribosomal subunitF: G proteinG: PilusH: ADP-ribosyliating enzymeI: mesosomeJ: FlagellumK: transposon537: mediates adherence of bacteria to mucous membranes

Answer 11

G

Question 12

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: capsuleB: periplasmic spaceC: peptidoglycanD: lipid AE: 30S ribosomal subunitF: G proteinG: PilusH: ADP-ribosyliating enzymeI: mesosomeJ: FlagellumK: transposon538: is the toxic component of endotoxin

Answer 12

D

Question 13

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 blueB: if you forget to stain with the red dye (safranin or basic fuchin), both gram-positive bacteria and gram-negative bacteria will appear blueC: if you forget to heat-fix, both gram-positive bacteria and gram-negative bacteria will appear blueD: 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

Answer 13

A

Question 14

block two, 8: regarding bacterial spores, which one of the following is the most accurate?A: one spore germinates to form one bacteriumB: they are produced primarily within human red blood cellsC: they are killed by boiling by at sea level but not high altitudeD: they are produced by anaerobes only in the presence of oxygenE: they contain endotoxin, which accounts for their ability to cause disease

Answer 14

A

Question 15

27: the effects of antibody on bacteria include each of the following except:A: lysis of gram-negative bacteria in conjunction with complementB: augmentation of phagocytosisC: increase in the frequency of lysogenyD: inhibition of adherence of bacteria to mucosal surfaces

Answer 15

C

Question 16

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 dismutaseD: the lack catalase

Answer 16

A

Question 17

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 cellsC: bacterial and human ribosomes are of different sizes and chemical compositionsD: bacterial cells possess peptidoglycan, whereas human cells do not

Answer 17

B

Question 18

9: which one of the following processes involves a sex pilus?A: transduction of a chromosome geneB: transposition of a mobile genetic elementC: integration of a temperate bacteriophage D: conjunction resulting in transfer of an R (resistance) factor

Answer 18

D

Question 19

14: which of the following events is most likely to be due to bacterial conjugation?A: a strain of corynebacterium diphtheriae produces a toxin encoded by a prophageB: a strain of pseudomonas aeruginosa produces produces beta-lactamase encoded by a plasmid of another gram-negative organismC: an encapsulated strain of sterptococcus pneumoniae acquires the gene for capsule formation from an extract of DNA from another encapsulated strainD: a gene encoding resistance to gentamicin in the escherichia coli chromosome appears in the genome of a bacteriophage that has infected e coli

Answer 19

B

Question 20

31: each of the following statements concerning the mechanisms of resistance to antimicrobial drugs is correct except:A: R factors are plasmids that carry the genes for enzymes that modify one or more drugsB: resistance to some drugs is due to a chromosomal mutation that alters the receptor for the drugC: resistance to some drugs is due to transposoms genes that code for enzymes which inactivate the drugsD: resistance genes are rarely transferred by conjugation

Answer 20

D

Question 21

select the one lettered option that is most closely associated with the numbered items.A: transductionB: conjugationC: DNA transformationD: Transposition44: During an outbreak of gastrointestinal disease caused by an escherichia coli strain sensitive to ampicillin, tetracycline, and chloramphenicol, a stool sample from one patient yields E. coli with the same serotype resistant to the three antibiotics

Answer 21

B

Question 22

select the one lettered option that is most closely associated with the numbered items.A: transductionB: conjugationC: DNA transformationD: Transposition45: a mutant cell line lacking a functional thymidine kinase gene was exposed to a preparation of DNA from normal cells; under appropriate growth conditions, a colony cells was isolated that makes thymidine kinase

Answer 22

C

Question 23

block one, 28: the emergence of antibiotic resistant bacteria, especially in enteric gram-negative rods, is an extremely important phenomenon. the acquisition of resistance most commonly occurs by a process that involves a sex pilus and the subsequent transfer of plasmids carrying one or more transposons. which one of the following is the name that best describes this process?A: conjugationB: combinationC: transformationD: transductionE: translocation

Answer 23

A

Question 24

5: which statement is most accurate regarding the drug depicted in the diagram?(i’ll post the picture on fb)A: it inhibits DNA synthesisB: it is bacteriostaticC: it binds to 30S ribosomesD: it prevents formation of folic acid

Answer 24

C

Question 25

6: each of the following statements regarding the selective action of antibiotics on bacteria is correct except:A: chloramphenicol affects the large subunit of the bacterial ribosome, which is different from the large subunit of the human ribosomeB: isoniazid affects the DNA polymerase of bacteria but not that of human cellsC: sulfonamides affect folic acid synthesis in bacteria, a pathway that does not occur in human cellsD: penicillins affect bacteria rather than human cells because bacteria have a cell wall, whereas human cells do not

Answer 25

B

Question 26

11: each of the following statements concerning the mechanism of action of antimicrobial drugs is correct except:A: vancomycin acts by inhibiting peptidoglycan synthesisB: quinolones such as ciprofloxacin act by inhibiting the DNA gyrase of bacteriaC: erythromycin is a bactericidal drug that disrupts cell membranes by a detergent-like actionD: aminoglycosides such as streptomycin are bactericidal drugs that inhibit protein synthesis

Answer 26

C

Question 27

12: each of the following statements concerning the resistance of bacteria to antimicrobial drugs is correct except:A: resistance to chloramphenicol is known to be due to an enzyme that acetylates the drugB: resistance to penicillin is known to be due to reduced affinity of transpeptidasesC: resistance to penicillin is known to be due to cleavage by beta-lactamaseD: resistance to tetracycline is known to be due to an enzyme that hydrolyzes the ester linkage

Answer 27

D

Question 28

18: each of the following statements concerning the mechanism of action of antibacterial drugs is correct except:A: cephalosporins are bactericidal drugs that inhibit the transpeptidase reaction and prevent cell wall synthesisB: tetracyclines are bacteriostatic drugs that inhibit protein synthesis by blocking tRNA bindingC: aminoglycosides are bacteriostatic drugs that inhibit protein synthesis by activating ribonuclease, which degrades mRNAD: erythromycin is a bacteriostatic drug that inhibits protein synthesis by blocking translocation of polypeptide

Answer 28

C

Question 29

23: chemical modification of benzylpenicillin (penicillin G) has resulted in several beneficial changes in the clinical use of this drug. which one of the following is not one of those beneficial changes?A: lowered frequency of anaphylaxisB: increased activity against gram-negative rodsC: increased resistance to stomach acidD: reduced cleavage by penicillinase

Answer 29

A

Question 30

24: each of the following statements concerning resistance to antibiotics is correct except:A: resistance to aminoglycosides can be due to phosphorylating enzymes encoded by R plasmidsB: resistance to sulfonamides can be due to enzymes that hydrolyze the five-membered ring structureC: resistance to penicillins can be due to alterations in biding proteins in the cell membraneD: resistance to cephalosporins can be due to cleavage of the beta-lactam ring

Answer 30

B

Question 31

30: each of the following statements concerning penicillin is correct except:A: an intact beta-lactam ring of penicillin is required for its activityB: the structure of penicillin resembles that of a dipeptide of alanine, which is a component of peptidoglycanC: penicillin is a bacteriostatic drug because autolytic enzymes are not activatedD: penicillin inhibits transpeptidases, which are required for cross-linking peptidoglycan

Answer 31

C

Question 32

31: each of the following statements concerning the mechanisms of resistance to antimicrobial drugs is correct except:A: R factors are plasmids that carry the genes for enzymes that modify one or more drugsB: resistance to some drugs is due to a chromosomal mutation that alters the receptor for the drugC: resistance to some drugs is due to transposon genes that code for enzymes which inactivate the drugsD: resistance genes are rarely transferred by conjugation

Answer 32

D

Question 33

35: each of the following statements concerning the drug depicted in the diagram is correct except: (diagram will be posted to fb)A: the drug is bacteriostaticB: the drug inhibits cell wall synthesisC: the drug is made by a fungusD: the portion of the molecule required for activity is labeled B

Answer 33

B

Question 34

Select the one lettered option that is most closely associated with the numbered items.A: PenicillinsB: AminoglycosidesC: ChloramphenicolD: RifampinE: Sulfonamides40: Inhibit(s) bacterial RNA polymerase

Answer 34

D

Question 35

Select the one lettered option that is most closely associated with the numbered items.A: PenicillinsB: AminoglycosidesC: ChloramphenicolD: RifampinE: Sulfonamides43: inhibit(s) folic acid synthesis

Answer 35

E

Question 36

Select the one lettered option that is most closely associated with the numbered itemsA: AmpicillinB: NafcillinC: ClindamycinD: GentamicinE: TetracyclineF: Amphotericin BG: CiprofloxacinH: RifampinI: SulfonamideJ: Erythromycin546: Inhibits protein synthesis by blocking formation of the initiation complex so that no polysomes form

Answer 36

D

Question 37

Select the one lettered option that is most closely associated with the numbered itemsA: AmpicillinB: NafcillinC: ClindamycinD: GentamicinE: TetracyclineF: Amphotericin BG: CiprofloxacinH: RifampinI: SulfonamideJ: Erythromycin547: inhibits DNA gyrase

Answer 37

G

Question 38

Select the one lettered option that is most closely associated with the numbered itemsA: AmpicillinB: NafcillinC: ClindamycinD: GentamicinE: TetracyclineF: Amphotericin BG: CiprofloxacinH: RifampinI: SulfonamideJ: Erythromycin548: inhibits folic acid synthesis

Answer 38

I

Question 39

Select the one lettered option that is most closely associated with the numbered itemsA: AmpicillinB: NafcillinC: ClindamycinD: GentamicinE: TetracyclineF: Amphotericin BG: CiprofloxacinH: RifampinI: SulfonamideJ: Erythromycin549: inhibits peptidoglycan synthesis; resistant to beta-lactamase

Answer 39

B

Question 40

Select the one lettered option that is most closely associated with the numbered itemsA: AmpicillinB: NafcillinC: ClindamycinD: GentamicinE: TetracyclineF: Amphotericin BG: CiprofloxacinH: RifampinI: SulfonamideJ: Erythromycin550: inhibits RNA polymerase

Answer 40

H

Question 41

block one, 38: regarding antimicrobial drugs that act by inhibiting nucleic acid synthesis in bacteria, which one of the following is the most accurate?A: quinolones, such as ciprofloxacin, inhibit the RNA polymerase in bacteria by acting as nucleic acid analoguesB: rifampin inhibits the RNA polymerase in bacteria by binding to the enzyme and inhibiting messenger RNA synthesisC: Sulfonamides inhibit the DNA polymerase in bacteria by causing chain termination of the elongating strandD: trimethoprim inhibits the DNA polymerase in bacteria by preventing the unwinding of double-stranded DNA

Answer 41

B

Question 42

21: each of the following statements concerning the killing of bacteria is correct except:A: lysozyme in tears can hydrolyze bacterial cell wallsB: silver nitrate can inactivate bacterial enzymesC: detergents can disrupt bacterial cell membranesD: ultraviolet light can degrade bacterial capsules

Answer 42

D

Question 43

34: each of the following statements concerning the killing of bacteria is correct except:A: a 70% solution of ethanol kills more effectively than absolute (100%) ethanolB: an autoclave uses steam under pressure to reach the killing temperature of 121 degrees CC: the pasteurization of milk kills pathogens but allows many organisms and spores to surviveD: iodine kills by causing the formation of thymine dimers in bacterial DNA

Answer 43

D