Test Answers on Chapter 20 – Flashcards
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Penicillin was considered a miriacle drug for all of the following reasons except:
A It was the first antibiotic
B it doesn't affect eukaryotic cells
C It inhibits gram-positive cell wall synthesis
D it has selective toxicity
E it kills a bacteria
|A. It was the first antibiotic
A drug that inhibits mitosis, such as griseofulvin, would be more effective against:
A gram positive bacteria
B Gram negative bacteria
D wall-less bacteris
Most of the available antimicrobial agents are effective against:
E All of the above
Antimicrobial peptides work by:
A inhibiting protein synthesis
B disrupting the plasma membrane
C complementary base pairing with DNA
D inhibiting cell-wall synthesis
E hydrolyzing peptidoglycan
|B Disrupting the plasma membrane
In what ways are semisynthetic penicillins and natural penicillins alike?
A both are broad spectrum
B both are resistant to penicillinase
C both are resistant to stomach acids
D both are bactericidal
D both are based on B-lactam
|E. Both are based on B-lactam
Which of the following antibiotics is not bactericidal?
Which of the following does not belong with the others?
The antibiotic tetracycline binds to the 30s subunit of the ribosome as shown in figure 20.1. ;The effect is to:
A prevent attachment of tRNA
B prevent peptide bond formation
C prevent transcription
D stop teh ribosome from moving along the mRNA
E. prevent attachment of tRNA and mRNA
|B. prevent peptide bond formation
The antibiotic cycloheximide binds to the 60s subunit of the ribosome as shown in figure 20.2 the effect is to:
A prevent mRNA -ribosome binding in eukaryotes
B prevent peptide bond formation in prokaryotes
C prevent poypeptide elongation in eukaryotes
D prevent transcription in prokaryotes
E prevent ribosome formation in bacteria
|C. Prevent polypeptide elongation in eukaryotes.
Which of these antimicrobial agents has the fewest side effects:
Which of the following drugs does not act by competitive inhibition?
Which of the following methods of action would be bacteriostatic?
A competitive inhibition with folic acid synthesis
B inhibition of RNA synthesis
C injury to plasma membrane
D inhibition of cell wall synthesis;
E competitive inhibition with DNA gyrase
|B. Inhibition of RNA synthesis
Which of the following antibiotics is recommended for use against gram-negative bacteria?
Which of the following antimicrobial agents is recommended for use against fungal infections?
A amphotericin B
|A. Amphotericin B
More than half of our antibiotics are
A produced by fungi
B produced by bacteria
C synthesized in laboratories
D produced by Fleming
E Produced by eukaryotic organisms
|B Produced by bacteria
Which compound would be the most useful to treat candidiasis?
Which of the following antibiotics are used to treat fungal infections;
B 3, 4
E all of the antibiotics
Which of the following antibiotics does not interfere with cell wall synthesis?
C natural penicillins
d senisyntheti penicillins
The antimicrobial drugs with the broadest spectrum of activity are:
Which of the following statements is false?
A fluoroquinolone inhibits DNA synthesis
B acyclovir inhibits DNA synthesis
C amantadine inhibits release of viral nucleic acid
D Interferon inhibits glycolysis
E azoles inhibit plasma membrane synthesis
|D. Interferon inhibits interferon
Protozoan and helminthic diseases are difficult to treat because:
A their cells are structurally and functionally similar to human cells
B They replicate insie human cells
C They dont have ribosomes
D They don't reproduce
E They have more genes than bacteria
|A. Their cells are structurally and functionally similar to human cells
Which of the following organisms would most likely be sensitive to natural penicillin?
A L forms
B streptococcus pyogenes
C penicillinase-producing Neisseria gonorrhoeae
|B. Streptococcus pyogenes
Which of the following statements about drug resistance is false?
A it may be carried on a plasmid
B it may be transferred from one bacterium to another during conjugation
C it may be due to enzymes that degrade some antibiotics
D it is found only in gram-negative bacteria
E it may be due to increased uptake of a drug
|D. It is found only in gram-negative bacteria.
Which of the following does not constitute an advantage of using two antibiotics together?
A it can prevent drug resistance
B It lessens the toxicity of individual drugs
C two are always twice as effective as one
D it allows treatment to be provided prior to diagnosis
E all of the above are advantages
|C. Two are always twice as effective as one
The structure of the influenza drug Tamiflu and Salic acid, the substrate for influenza virus's neuramidase, are shown in figure 20.6. ;What is the method of action of Tamiflu?
A inhibits cell wall synthesis
B inhibits plasma membrane synthesis
C inhibits synthesis of neuramidase
D competitive inhibition
E prevents synthesis of virus spikes
|D. Competitive inhibition
The antibiotic chloramphenicol Binds to the 50s subunit of the ribosome as shown in figure 20.3. ;The effect is to
A prevent attachment of tRNA
B prevent peptide bond formation
C prevent transcrition
D stop ribosome from moving along the mRNA
E prevent polypeptide formation in eukaryotes.
|A. Prevent attachment of tRNA
Drug resistance occurs;
A because bacteria are normal microbiota
B when antibiotics are used indiscriminately
C against antibiotics and not against synthetic chemotherapeutic agents
D when antibiotics are taken after symptons disappear
E all of the above
|B. when antibiotics are used indiscriminately
Which of the following would be selective against the tubercle bacillus?
A bacitracin - inhibits peptidoglycan synthesis
B ethambutol-inhibits mycolic acid synthesis
C streptogramin inhibits protein synthesis
D Streptomycin inhibits protein synthesis
D Vancomycin inhibits peptidoglycan synthesis
|B. ethambutol- inhibits mycolic acid synthesis
In the presence of penicillin, a cell dies because
A it lacks a cell wall
B it plasmolyzes
C it undergoes osmotic lysis
D it lacks a cell membrane
E its contents leak out
|C. It undergoes osmotic lysis
Lamisil is an allylamine used to treat dermatonycoses. ;Lamisil's method of action is similar to that of
A polymyxin B
B azole antibiotics
|B Azole antibiotics
Niclosamide prevents ATP generation in mitochondria. You would expect this drug to be effective against
A gram-negative bacteria
B gram-positive bacteria
D mycobacterium tuberculosis
Which of the following statements about drugs that competitively inhibit DNA polymerase or RNA polymerase is false?
A they cause mutations
B they are used against viral infections
C they can affect hot cell DNA
D they are too dangerous to use
E they interfere with protein synthesis
|D They are too dangerous to use.
Which of the following does not affect eukaryotic cells?
A antiprotozoan drugs
B antihelminthic drugs
C antifungal drugs
D nucleotide analogs
E semisynthetic penicillins
|E. semisynthetic penicillins
Mebendazole is used to treat cestode infections. It interfers with microtubule formation; therefore, it would not affect
D human cells
Which of the following antibiotics causes misreading of mRNA
A aminoglycoside-changes shape of 30s units
B chloramphenicol-inhibits peptide bonds at 50s subunit
C oxazolidinine-prevents formation of 70s ribosome
D streptogamin - prevents release of peptide from 70s ribosome
E tetracyclines - bind with 30s subunit
|A. aminoglycoside changes shape of 30s units
The antibiotic actinomycin D binds between adjacent G-C pairs, thus interfering with
C cellular respiration
D plasma membrane function
E peptide bond formation
Use of antibiotics in animal feed leads to antibiotic-resistance bacteria because
A bacteria from other animals replace those killed by the antibiotics
B the few surviving bacteria that are affected by the antibiotics develop immunity to the antibiotics, which they pass on to their progeny
C the antibiotics cause new mutations to occur in the surviving bacteria which results in reistance
D the antibiotics kill susceptible bacteria but the few that are naturally resistant live and reproduce and their progeny repopulate the host
E the antibiotics persist in soil and water
|D the antibiotics kill susceptible bacteria, but the few that are naturally resistant live and reproduce, and their progeny repopulate the host animal.