Quizzes for Microbiology
There are over 100 MCQs and filling questions in this document to test your basic understand about Microbiology....
1. The first microorganisms to colonize the gut of infants living in developed countries is: a. Streptococcus pyogenes b. Escherichia coli c. Staphylococcus aureus. d. Staphylococcus epidermidis 2. Which human body site is NOT a favorable place for abundant microbial growth because it is subject to periodic drying? a. Skin surface. b. Respiratory tract c. Gastrointestinal tract d. Urogenital tract 3. The most common fungi found on the skin are: a. Staphylococcus spp b. Propionibacterium spp c. Malassezia spp. d. Streptococcus spp 4. Incorporation of ________ into the calcium phosphate crystal tooth matrix increases resistance to tooth decay. a. Fluoride. b. Nitrite c. Bromide d. Calcium 5. Intestinal microorganisms perform which of the following functions? a. They absorb water from digested food material b. They produce about half the nitrogen gas present in the atmosphere c. They synthesize all the essential vitamins required by humans. d. They modify bile acids into activated steroid compounds 6. The upper respiratory tract consists of all the following EXCEPT: a. The oral cavity b. The bronchi. c. The nasopharynx d. The pharynx 7. A local acidic environment in the vagina of adult women is maintained by fermentation of: a. Glucose b. Glycogen. c. Estrogen d. Lactose 8. Structures involved in the specific adherence of a pathogen to host cell surfaces include all the following EXCEPT: a. Pili. b. Fimbriae c. Transferrin d. Capsules 9. ________ probably occurs because nonvirulent or weakly virulent mutants grow faster and, after successive transfers to fresh media, such mutants are selectively favored. 1
a. b. c. d.
Attenuation. Invasiveness Toxicity Pathogenicity 10. As with other pathogenicity islands, SPI-1 is a collection of virulence genes flanked by sequences suggesting a(n): a. Plasmid transfer b. Transposable genetic element. c. Virus insertion d. Absence of transcriptional regulation 11. What is the fibrinolytic substance produced by Streptococcus pyogenes that dissolves fibrin clots and makes further invasion possible? a. Streptokinase. b. Coagulase c. Lipase d. Hyaluronidase 12. Which of the following is NOT a host risk factor for infection? a. Health status of the host b. Stress c. Age d. Relative virulence. 13. Growth of a microorganism after it has gained access to host tissues is called ………………………… . (infection) 14. Most skin microorganisms are associated directly or indirectly with the……………….. . 15. Diets high in (sucrose) ………………….especially promote dental caries. 16. Probiotics……………………….are live cultures of intestinal bacteria that, when administered to a host, often confer a health benefit. 17. Iron-chelating compounds that help many bacteria produce iron from the environment are called …………………….. Siderophore. 18. Invasion………………………….is the ability of a pathogen to grow in host tissue in such large numbers that it inhibits host function. 19. Coagulase……………………………..is a protein that functions in the clotting of blood. 20. Botulinum toxin consists of AB toxin…………………that are the most potent biological toxins known. 21. The host-parasite interaction is a dynamic relationship between the two organisms, influenced by changing conditions in the pathogen, the host, and the environment. True/ False 22. In heavy plaque on the surface of the teeth, aerotolerant anaerobes such as streptococci and lactobacilli may predominate. True/ False (In heavy plaque, filamentous obligately anaerobic organisms such as Actinomyces may predominate. Thus, dental plaque is a mixed-culture biofilm (Section 23.4), consisting of a relatively thick layer of bacteria from several different genera as well as accumulated bacterial products. 23. In many cases, pathogenic microorganisms cannot colonize mucous membranes because of the competitive effects of the normal flora. True/ False 2
24. An iron solution given to an infected animal greatly decreases the virulence of some pathogens. True/ False(a dietary iron supplement given to an infected animal greatly increases the virulence of some pathogens. 25. Endotoxins generally cause massive secretion of fluid into the intestinal lumen, resulting in vomiting and diarrhea. True/ False 26. Pathogens use all the following strategies to gain access to nutrients in a host EXCEPT: a. The production of a diverse microflora. b. The production of unique growth factors and invasive enzymes c. The production of potent biological toxins d. The production of specialized attachment structures 27. The ability of a parasite to inflict damage on a host is called: a. Disease b. Virulence c. Pathogenicity. d. Infection 28. Microbial populations thrive on the surface of the skin at all the following sites EXCEPT: a. The umbilicus b. The underarms c. The nipples d. The legs. 29. Dental caries results from the production of locally high concentrations of ________ by resident microflora. a. Inorganic acids b. Glycoproteins. c. Hydrogen sulfide d. Organic acids 30. The most common single organism found in the stomach is: a. Helicobacter pylori. b. Escherichia coli c. Bacteroides spp. d. Clostridium spp. 31. Antibiotic treatment may result in infection and the development of colitis caused by overgrowth of antibiotic organisms such as: a. Methanobrevibacter smithii b. Bacteroides spp c. Clostridium difficile. d. Fusobacterium spp 32. The microorganisms most commonly found on the mucosal surfaces of the respiratory tract include all the following EXCEPT: a. Gram-negative bacilli. b. Diphtheroids c. Gram-negative cocci d. Staphylococci 33. The relative ability of a pathogen to cause disease is called: a. Virulence 3
b. Pathogenicity. c. Infection d. Disease 34. Growth of Brucella abortus occurs very rapidly in the placenta of infected cattle because the placenta is the only tissue that contains high concentrations of: a. Erythritol. b. Lactoferrin c. Glucose d. Glycogen 35. An organism that exemplifies the extreme of toxicity is: a. Candida albicans b. Legionella pneumophila c. Streptococcus pneumoniae d. Clostridium tetani. 36. ________ digests the intercellular matrix, enabling organisms to spread from an initial site of infection. a. Dnase b. Coagulase c. Lipase d. Hyaluronidase. 37. Diphtheria toxin is formed only by strains of Corynebacterium diphtheriae that: a. Contain a T plasmid b. Are lysogenized by bacteriophage ß. c. Are replicating in the presence of large concentrations of iron d. Contain a mobile genetic element 38. The organisms that colonize, invade, and damage the human body through direct and indirect means are known as …………..pathogens. 39. Infections frequently begin at sites in the animal's mucous membrane 40. Various environmental and host factors may influence the composition of the skin microflora; these include the weather, the age of the host, and……………..persional hygiene. 41. The composition of the intestinal flora in humans varies considerably and is somewhat dependent on ……………. . Diet 42. A loose network of polymer fibers extending outward from a cell is called a ………… glycocalyx 43. …………………….Attenuatedstrains are often used for production of vaccines, especially viral vaccines. 44. The genes that initiate the invasion process in Salmonella spp. Are contained on the chromosomal…………….. Pathogenicity island 1 (SPI1). 45. The three categories of exotoxins are the…………cytolytic toxin, the AB toxins, and the superantigen toxins. 46. Flagella can increase adherence to host cells.True/ False 47. Neither Clostridium tetani nor Clostridium botulinum is very invasive, and virtually all pathogenic effects are the result of neurotoxicity. True/ False
48. A pathogen causes disease only in the absence of normal host resistance.True/ False 49. Saliva is a good growth medium because nutrients are present in high concentrations and because it contains vanishingly low levels of antibacterial substances. True/ False 50. Bacteria make up about one-third of the weight of fecal matter.True/ False
Chapter: Control of microbial 1. When using heat sterilization, which type of cell is most likely to survive conditions that are less than optimal, for example, an error that resulted in heating of the solution to only 115 oc, and only for a few minutes? A. Mycobacterium tuberculosis B. Salmonella typhi C. Escherichia coli O157: H7 D. Endospores of Bacillus subtilis E. More than one of the above 2. Which of the following kinds of cells might be resistant to a germicide used in a hospital? A. Salmonalla typhi B. Escherichia coli C. Endospores of Bacillus subtilis D. Mycobacterium tuberculosis E. More than one of the above 3. What is the mode of action of sulfanilamide? A. Blocking synthesis of protein B. Blocking synthesis of the cell wall C. Blocking mRNA synthesis D. Blocking folic acid synthesis 4. What is the mode of action of penicillin? A. Blocking synthesis of protein B. Blocking mRNA synthesis C. Blocking folic acid synthesis D. Blocking synthesis of the cell wall 5. What is the mode of action of tetracycline? A. Blocking synthesis of protein B. Blocking folic acid synthesis C. Blocking synthesis of the cell wall D. Blocking mRNA synthesis 6. What is the mode of action of streptomycin? A. Blocking folic acid synthesis B. Blocking synthesis of the cell wall C. Blocking synthesis of protein D. Blocking mRNA synthesis 7. Which of the following would be considered a growth factor analog? A. Tetracycline B. Penicillin C. Sulfanilamide D. Streptomycin E. All of the above 8. Which of the following would not be considered an antibiotic? 5
A. Penicillin B. Streptomycin C. Sulfanilamide D. Tetracycline E. All of the above 9. Which of the following would be considered a narrow spectrum antibiotic? A. Streptomycin B. Kanamycin C. Tetracycline D. Vancomycin 10. What is the mode of action of AZT? A. Blocking synthesis of the cell wall B. Blocking DNA synthesis C. Blocking synthesis of protein D. Blocking mRNA synthesis 11. The antifungal drugs in the polyoxin group, based on their mode of action, are most like that of the antibacterial drug __________. A. Streptomycin B. Tetracycline C. Sulfanilamide D. Penicillin 12. Which of the following antibiotics might be dismissed immediately as a way to treat a disease caused by a mycoplasma? A. Streptomicin B. Kanamycin C. Tetracycline D. Penicillin 13. Most clinically significant antibiotic resistance results from _________. A. Mutations in pathogen chromosomal genes B. Development of an immune response in the microorganism C. Acquisition of a plasmid encoding antibiotic resistance 14. The process by which all living cells, viable spores, viruses, and viroids are either destroyed or removed from an object or habitat is called A. Sterilization B. Disinfection C. Sanitization D. Antisepsis E. The definition would apply to all of the above 15. The correct conditions for an autoclave are A. 15 psi of steam pressure and 121 oc B. 5 psi of steam pressure and 100 oc C. 35 psi of steam pressure and 212 oc D. 30 psi of steam pressure and 180 oc 16. If a soil sample were suspended in water, boiled for 20 minutes, then plated on nutrient agar, and incubated aerobically, which of the following would most likely grow on the plates? A. Treponema pallidum (a spirochete) B. Escherichia coli C. Pelodictyon (a photosynthetic bacterium) D. Clostridium botulinum 6
E. Bacillus subtilis 17. A bacteriocidal agent could be distinguished from a bacteriostatic agent by A. Comparing total cell counts, and the viable cell counts following addition of each agent. B. Determining the influence of each on growth rate. C. Determining the relative concentration required to inhibit growth. D. Comparing the rate of protein synthesis in following inhibition of growth. E. Determining the slope of the curve in the death phase. 18. Agents that kill or destroy bacteria are said to be A. Inhibitory B. Bactericidal C. Bacteriostatic D. All of the above 19. Compared with the decontamination, disinfection is A. More aggressive B. Less aggressive C. Equally aggressive D. Either more or less aggressive, depending on the situation in question 20. The destruction of all life forms is called A. Disinfection B. Sterilization C. Decontamination D. Any of the above, depending on the circumstances. 21. The time required for a 10-fold reduction in population density at a given temperature is called the A. Thermal death time. B. Mean sterilization time. C. Decimal reduction time. D. Temperature dependent logarithmic death time. 22. The process by which macromolecules lose their structures and abilities to function is called A. Denaturation B. Sterilization C. Thermal death D. None of the above 23. Which statement(s) is/are true about heat sterilization? A. Some substances are sterilization more rapidly at high ph, others at low ph. B. High concentrations of sugars and salt influence sterilization time. C. The amount and safe of water in a substance is a major factor in heat resistance. D. All of the above 24. Which of the following are classified as electromagnetic radiation? A. Microwaves B. Ultraviolet rays C. X-rays and gamma rays D. All of the above 25. UV radiation is antimicrobial because A. The radiation generates significant amounts of heat within the given cell. B. The energy present causes breaks in the DNA molecules. 7
C. The radiation generates magnetic poles which denature the cellular components. D. All of the above 26. The antimicrobial effectiveness of which of the following is limited to exposed surfaces? A. Microwaves B. Ultraviolet rays C. X-rays and gamma rays D. Electrons 27. When discussing radiation, the _________ is the radiation enery output and the __________ is the absorted radiation dose. A. Roentgen/rad B. Rad/ Roentgen C. Gray (Gy)/Roentgen D. Rad (source)/rad (effective) 28. For microbiological purposes, the two most commonly used radioisotopes are isotopes of A. Cobalt and potassium B. Cesium and potassium C. Cobalt and cesium D. Cobalt and iodine. 29. The type of filter most often used as a prefilter is a A. Depth filter. B. Membrane filter. C. Nucleation track filter. D. Microbistat filter. 30. The type of filter most often used for basic sterilization is a A. Depth filter B. Membrane filter C. Nucleation track filter D. Microbistat filter 31. The type of filter most often used in electron microscopy is a A. Depth filter B. Membrane filter C. Nucleation track filter D. Microbistat filter 32. The type of filter most often using a vacuum or pump to force the filtrate through is a A. Depth filter B. Membrane filter C. Nucleation track filter D. Microbistat filter 33. The action of bacteriolytic chemical agents can be observed by noting a(n) A. Increase in the turbidity of the medium B. Decrease in the turbidity of the medium C. Change in the color of the medium D. Change in the surface tension of the medium 34. In the agar diffusion method of studying antimicrobial action, the _________ is measured. 8
A. B. C. D.
Diameter of the zone of inhibition Diameter of the individual microbial colonies Turbidity of the medium Distance between the microbial colonies 35. ________ are applied to living tissues; _________ are used on inanimate objects. A. Disinfectants/sterilants B. Antiseptics/sterilants C. Antiseptics/disinfectants D. Disinfectants/sterilants 36. Cold sterilization is performed using A. Exceptionally low temperatures. B. Dry ice. C. Compounds such as ethylene oxide D. High pressure chambers. 37. The vegetative cells of Mycobacterium tuberculosis are resistant to many germicides because of A. An extra membranous layer between the cell wall and the plasma membrane B. The complex nature of the plasma membrane itself. C. The complex nature of the cell wall. D. The lattice work found in the glycocalyx. 38. Water is most commonly sterilized with A. Flourine. B. Chlorine. C. Bromine. D. Iodine. 39. Sulfanilamide is an analog of A. Citric acid. B. P-aminobenzoic acid. C. Folic acid. D. Sulfuric acid. 40. The quinolones are synthetic antibacterial compounds that A. Interact with bacterial DNA gyrase B. Increase the supercoiling rate in the bacterial DNA. C. Prevent the formation of pre-RNA segments. D. All of the above. 41. Of all the antibiotics that have been discovered only ________ have been of practical value in medicine. A.