The Hardest Microbiology Questions And Answers! Quiz

________ __________ are activities of a chemotherapeutic agent that damage the host either by inhibiting the same process in the host as in the target cell or by damaging other processes. (2 words)  

A neuraminidase inhibitor called __________ is sometimes used in the treatment of people infected with influenza viruses.  

One way in which organisms may exhibit resistance to a drug is the ability to pump the drug out of the cell immediately after it has entered.  

• True

• False

 The effects of most antimicrobial drugs are greater if the microorganisms are actively growing.  

• True

• False

R plasmids, transposons, integrons and gene cassettes have each contributed to the spread of bacterial antibiotic resistance.  

• True

• False

Who is usually credited with the discovery of penicillin?  

• Fleming

• Florey and Chain

• Duchesne

• Ehrlich

A(n) __________ is a drug that blocks the function of a metabolic pathway.  

______________ ________________ from Streptomyces spp. binds to the sterols in fungal membranes, disrupting membrane permeability and causing leakage of cell constituents.  (2 words)  

One way that the development of drug resistance in viruses has been reduced has been by the use of a cocktail of several drugs at high doses.  

• True

• False

Treatment of fungal infections is more difficult than treatment of bacterial infections because the greater metabolic similarity between the fungi and their hosts limits the ability of a drug to have a selective toxicity.  

• True

• False

Bacteria in biofilms or abscesses may be replicating very slowly and are therefore resistant to chemotherapy because many agents affect pathogens only if they are actively growing and dividing.  

• True

• False

 The minimum lethal concentration (MLC) is the lowest concentration of drug from which organisms fail to recover when removed from the drug.  

• True

• False

Which of the following affects the size of the clear zone in a disk diffusion test of antimicrobial susceptibility?  

•  the initial concentration of the drug


•  the solubility of the drug


• The diffusion rate of the drug

• All of the choices

 The lowest concentration of an antibiotic that prevents growth is the  

• Minimal inhibitory concentration (MIC). 


• Minimal lethal concentration (MLC). 


• 50% inhibitory dose.

• All of the choices

A drug that disrupts a microbial function not found in animal cells usually has a higher therapeutic index.  

• True

• False

The drug level required for the clinical treatment of a particular infection is called the  

• Therapeutic dose.


• Toxic dose.

• Therapeutic index.


• Minimal inhibitory concentration.

Chemotherapeutic agents that are artificially produced are most specifically referred to as __________.  

• Antimicrobial agents


• Synthetic drugs

• Antibiotics

• Semisynthetic drugs

The use of arsenic compound Salvarsan as a treatment for syphilis is credited to  

• Fleming

• Ehrlich

• Waksman

• Chain

 The most selective antibacterial agents are those that interfere with bacterial cell wall synthesis. This is because  

• Bacterial cell walls have a unique structure not found in eukaryotic host cells.

• Bacterial cell wall synthesis is easily inhibited whereas eukaryotic cell wall synthesis is more resistant to the actions of the drugs. 


• Eukaryotic cells do not take up the drugs. 


• eukaryotic cells inactivate the drugs before they can do any damage.

Metronidazole is used to treat Entamoeba infections.  

• True

• False

The chemotherapeutic agent must reach levels in the body that are ________ the pathogen’s MIC value if it is going to be effective.  

• Greater than

• Equal to

• less than

• None of the choices

 The concentration of an antimicrobial drug that is reached in the body will depend on  

• The amount of drug administered.

• The route of administration and speed of uptake. 


• the rate at which the drug is cleared or eliminated from the body.

• all of the choices

Which of the following is (are) used by microorganisms to become resistant to a particular drug?  

• Enzymatic inactivation of the drug

• Exclusion of the drug from the cell

• An alternate metabolic pathway that bypasses the drug-sensitive step

• All of the choices

Which of the following inhibits protein synthesis?  

• Dapsone

• Erythromycin

• Penicillin

• Isoniazid

Sulfonamides and other drugs that inhibit folic acid synthesis have a high therapeutic index because  

• Humans do not use folic acid.


• Humans do not synthesize folic acid but obtain it in their diets.


• Humans synthesize folic acid by a process that is not sensitive to sulfonamides.


• None of these

Agents that are static and, therefore, do not kill infecting microorganisms are not useful as chemotherapeutic agents.  

• True

• False

Which of the following is a useful mechanism of action for an antibacterial drug?  

• Inhibition of cell wall synthesis

• Inhibition of protein synthesis

•  interference with RNA and DNA synthesis


• All of the choices

Which of the following is normally treated by antifungal creams and solutions?  

• systemic mycoses 


• superficial mycoses 


• Subcutaneous mycoses 


• Intramuscular mycoses

Chemotherapeutic agents that are natural products of microorganisms are most specifically referred to as __________.  

• Antimicrobial agents


• Synthetic drugs

• Antibiotics

• Semisynthetic drugs

Sulfonamides inhibit the production of folic acid and, therefore, inhibit the synthesis of __________.  

• Purines and pyrimidines

• Ribose

• Aromatic amino acids

• Peptidoglycan

Who is generally credited with the discovery of sulfanilamide as a chemotherapeutic agent?  

•  Gerhard Domagk

• Ernest Duchesne

• Ernst Chain

•  Robert Koch

The ratio of toxic dose to therapeutic dose is called the  

• Toxicity index.

• Phenol coefficient.


• Therapeutic index.

• Susceptibility quotient.

The minimal lethal concentration (MLC) is the  

• lowest concentration of a drug that prevents growth of a particular pathogen.

• Highest concentration of a drug that prevents growth of a particular pathogen.

• Lowest concentration of a drug that kills a particular pathogen.

• Highest concentration of a drug that kills a particular pathogen.

The E test is  

• A rapid serological test used to detect the presence of eastern equine encephalitis virus in cerebrospinal fluid.

• A quantitative antibiotic sensitivity test that utilizes plastic strips impregnated with an antibiotic of interest.

• Used to quantify levels of IgE antibody in serum samples. 


• Used to measure esculine levels in pasteurized milk.

Which of the following is the major reason why it has been difficult to treat viral infections with chemotherapeutic agents?  

• Viral metabolism resembles that of their hosts so there is no selective point of attack. 


• Viruses use the metabolic machinery of their hosts, which limits many of the potential points of attack.

• Viruses have no metabolism and therefore offer no selective point of attack.

• Actually, viruses are not difficult to treat with chemotherapeutic agents.

________, which is used to treat Toxoplasma gondii, is an analog of ________, an integral component of the eukaryotic electron transport system.  (answer, answer)  

Penicillin is frequently injected but not normally given orally because it is rapidly degraded in the stomach.  

• True

• False

Whose discovery of streptomycin stimulated an intense search for other antibiotics?  

• Waksman

• Ehrlich

• Fleming

• Pasteur

 Isoniazid is a narrow-spectrum antibiotic that  

• Is not useful as a chemotherapeutic agent.

• Is one of the few drugs effective against Mycobacterium tuberculosis.

•  is one of the few drugs effective against systemic fungal infections.


• None of the choices

Which of the following is a desirable general characteristic of antimicrobial drugs?  

•  selective toxicity


• Broad-spectrum of activity


• Bactericidal rather than bacteriostatic

• All of the choices

It is difficult to treat central nervous system infections because  

• the organisms causing such infections are usually resistant to most drugs.

• It is difficult for many drugs to penetrate the blood-brain barrier. 


• Most infections of the central nervous system are caused by fungi.

• toxic side effects can result in severe neurological damage.

________ and ________ can be used to prevent influenza A infections, reducing the incidence of influenza by 50 to 70% in an exposed population.  (answer, answer)  

Which of the following antibiotics specifically inhibits DNA synthesis?  

• Gentamycin

• Polymyxin B


• Quinolones

• Tetracycline

A plasmid bearing one or more antibiotic resistance genes is a(n)  

• F plasmid.

• A plasmid.

• R plasmid.

• D factor.

Which of the following does not inhibit protein synthesis?  

• Tetracycline

• Streptomycin

• Erythromycin

• Penicillin

• All of the choices inhibit protein synthesis

Aminoglycoside antibiotics  

•  inhibit cell wall synthesis.


• Inhibit folic acid biosynthesis.


• Bind to the 30S ribosomal subunit.


• Bind to bacterial DNA polymerase.

In addition to inhibiting the transpeptidation reaction in cell wall synthesis, penicillins may also destroy bacteria by  

• inhibiting DNA replication.

• Stimulating proteins to form holes in the plasma membrane. 


• inhibiting protein synthesis.

• none of the choices

 The antiviral drugs currently approved for use in HIV disease include  

• Nucleoside reverse transcriptase inhibitors. 


• Nonnucleoside reverse transcriptase inhibitors.

•   protease inhibitors. 


• fusion inhibitors.

• All of the choices