Chapter 1: An Invisible World * = Correct answer Multiple Choice
1. Which of the following is true of the microbial world? A. All microbes are harmful. B. Humans could survive without microbes. C. Many microbes are helpful.* D. Most microbes are pathogenic. Difficulty: Easy ASM Standard: 23, 24 2. Which of the following is when humans first suspected the existence of microbes? A. during the Industrial Revolution B. in prehistoric times* C. in the last century D. within the last 500 years Difficulty: Easy ASM Standard: 23 3. Which individual first observed unicellular organisms, which he called “animalcules,” using a microscope he developed? A. Robert Koch B. Louis Pasteur C. Thucydides D. Antonie van Leeuwenhoek* Difficulty: Easy ASM Standard: 6 4. To reduce the risk of open flame from Bunsen burners, microbiologists are increasingly using which of the following devices for easy, rapid benchtop sterilization of small pieces of equipment? A. autoclaves B. ethylene oxide C. incubators
D. microincinerators* Difficulty: Easy ASM Standard: 36
5. The Swedish botanist known for having developed an important biological classification system is which of the following people? A. Ernst Haeckel B. Carolus Linnaeus* C. Louis Pasteur D. Robert Whittaker Difficulty: Easy ASM Standard: N/A 6. Which kingdom was the only one found in Empire Prokaryota? A. Animalia B. Fungi C. Monera* D. Protista Difficulty: Easy ASM Standard: N/A 7. Which are the three currently accepted domains? A. Archaea, Bacteria, and Eukarya* B. Archaea, Prokaryota, and Eukaryota C. Bacteria, Fungi, and Protista D. Bacteria, Prokaryota, and Eukarya Difficulty: Easy ASM Standard: N/A 8. Which two taxonomic units are typically used to identify an organism when using binomial nomenclature? A. domain and kingdom B. genus and family C. genus and species* D. phylum and class Difficulty: Easy ASM Standard: N/A 9. Which of the following is not true about the process of fermentation? A. It can help preserve foods, preventing spoilage. B. It converts sugars to organic acids, alcohols, and/or gases such as carbon dioxide.
C. It is carried out exclusively by unicellular eukaryotes such as yeast.* D. It is used to make foods such as cheese and bread. Difficulty: Moderate ASM Standard: 11, 23, 26
10. The Romans may have reduced their risk of waterborne infectious diseases by using which of the following? A. a variety of pharmaceutical products B. aqueducts and a sewer system* C. prophylactic antibiotics D. quarantine of people with leprosy Difficulty: Moderate ASM Standard: 23 11. For which of the following is Thucydides known? A. developing an effective sewer system in ancient Greece, helping to reduce levels of disease in cities B. observing microbes, using a microscope, for the first time, even distinguishing between bacteria and fungi C. proposing that disease was caused by microorganisms D. realizing that people who had been infected by the Athenian plague had immunity to reinfection* Difficulty: Moderate ASM Standard: 23, 31 12. Ernst Haeckel proposed a classification system consisting of which of the following subgroups? A. five kingdoms B. four kingdoms* C. two domains and three kingdoms D. two domains and five kingdoms Difficulty: Moderate ASM Standard: N/A 13. Viruses not included in phylogenetic trees for which of the following reasons? A. It is too difficult to observe their characteristics. B. They are acellular and nonliving.* C. They do not have any genes, which prevents genetic analysis. D. They lack a nucleus. Difficulty: Moderate ASM Standard: 5 14. Which is the best description of the primary purpose of a phylogeny? A. Phylogenies show all the alterative names for each species. B. Phylogenies show all the common names for each species. C. Phylogenies show evolutionary relatedness between organisms.*
D. Phylogenies show interactions between species in a shared habitat. Difficulty: Moderate ASM Standard: 5 15. Current phylogenetic analyses include which of the following? A. information from a range of sources, including morphological, genetic, and biochemical data* B. information on visible similarities only C. information regarding how to classify organisms on the basis of external morphological characteristics and visible behaviors D. varied morphological and structural characteristics, with preference for leaving historical classifications to prevent confusion Difficulty: Moderate ASM Standard: 5 16. Diatoms are classified within which of the following domains? A. Archaea B. Bacteria C. Eukarya* D. Prokaryota Difficulty: Moderate ASM Standard: N/A 17. Horizontal gene transfer involves which of the following? A. any transfer of genes in a laboratory setting B. the transfer of genes from a virus to a bacterium or vice versa but not any other form of gene transfer C. the transfer of genes from one individual to another, including from one species to another, but not from parent to offspring* D. the transfer of genes from parent to offspring Difficulty: Moderate ASM Standard: 2, 4 18. Bacteria are generally identified to species by using which of the following? A. a combination of genetic, biochemical, and microscopic approaches* B. a combination of microscopic and physiological approaches, but not genetics C. primarily characteristics such as motility that can be visualized using microscopy D. primarily morphological characteristics of individual cells Difficulty: Moderate ASM Standard: 34, 36
19. For taxonomic classification of microbes, serological tests typically are used to do which of the following? A. determine complete genome sequences for microbes B. identify proteins on the basis of their reaction with specific antibodies* C. run analyses to identify whether particular genes are present D. visualize microbial external morphology Difficulty: Moderate ASM Standard: 34, 36 20. Which of the following is true of bacterial strains? A. They are closely related subtypes within a bacterial species that may or may not have similar properties.* B. They are informal bacterial groupings used for medical distinctions but not recognized for classification purposes. C. They are more distantly related to each other than are members of a single bacterial species. D. They are very similar bacteria with almost identical properties. Difficulty: Moderate ASM Standard: 5 21. Bergey’s Manual of Systematic Bacteriology is used primarily as which of the following?
A. a guide to bacterial shapes B. a historical account of changes in classification techniques C. a list and characterization of all known medically relevant microbes D. a reference for bacterial classification* Difficulty: Moderate ASM Standard: 34 22. Which of the following indicates how bacteria and viruses typically compare in size? A. Bacteria are indistinguishable from viruses. B. Bacteria are much larger than viruses.* C. Bacteria are much smaller than viruses. D. Bacteria are similar in size to viruses. Difficulty: Easy ASM Standard: N/A 23. Viruses are classified as which of the following? A. Archaea B. Bacteria C. Eukarya D. distinct from the three-domain system*
Difficulty: Moderate ASM Standard: 4 24. Which of the following is not a curved bacterial shape? A. bacillus* B. spirillum C. spirochete D. vibrio Difficulty: Easy ASM Standard: 34 25. Based just on the name, which of the following groups of bacteria contains entirely species that consume organic compounds for food? A. cyanobacteria B. green nonsulfur bacteria C. green sulfur bacteria D. nonphotosynthetic bacteria* Difficulty: Moderate ASM Standard: 11, 13, 20 26. Chitin cell walls are characteristic of which taxonomic group? A. algae B. archaea C. bacteria D. fungi* Difficulty: Moderate ASM Standard: 20 27. Yeasts are which of the following? A. a type of algae B. a type of protist C. any unicellular microbe D. unicellular fungi* Difficulty: Moderate ASM Standard: 20 28. The cell walls of archaeans often contain which of the following substances? A. cellulose B. chitin C. peptidoglycan D. pseudopeptidoglycan*
Difficulty: Moderate ASM Standard: 20 29. Which of the following is not true of archaeans? A. Some species live on the human body. B. They are genetically distinct from bacteria. C. They are only found in extreme environments.* D. They have substantial metabolic differences from bacteria. Difficulty: Difficult ASM Standard: 20 30. Which of the following is not true of algae? A. All the algae are classified together in one similar group closely related to green plants.*
B. Ingredients made from algae, including carrageenan, are used in food products. C. They are being used to develop biofuels. D. They are sometimes multicellular. Difficulty: Moderate ASM Standard: 20, 23, 26 31. Oral thrush is caused by which type of organism? A. algae B. bacteria C. fungi* D. protists
Difficulty: Moderate ASM Standard: 23 32. Mycotoxins are produced by which type of organism? A. archaeans B. heterotrophic protists C. molds* D. protozoans Difficulty: Moderate ASM Standard: 23 33. Which of the following is not a common use of fungi? A. the production of alcoholic beverages B. the production of carrageenan* C. the production of cyclosporine D. the production of penicillin
Difficulty: Moderate ASM Standard: 20, 23, 26 34. The guinea worm is best described as which of the following? A. a helminthic parasite transmitted by consuming contaminated water* B. a type of mold that grows into a worm-like shape and produces antimicrobial chemicals
C. a type of protist found in water that has not been properly treated D. a type of protozoan that is unusual because it is multicellular Difficulty: Moderate ASM Standard: 23 35. Which of the following is true of the genetics of viruses? A. Viruses always contain DNA and force host cells to produce RNA. B. Viruses always contain DNA and RNA. C. Viruses always contain RNA and force host cells to produce DNA. D. Viruses can contain either DNA or RNA, but not both.* Difficulty: Moderate ASM Standard: N/A True/False 36. All organisms studied in the field of microbiology are visible only with a microscope. Answer: False Difficulty: Easy ASM Standard: N/A 37. Older scientific names are typically derived from Latin. Answer: True Difficulty: Easy ASM Standard: N/A 38. Animal cells are generally about the same size as bacterial cells. Answer: False Difficulty: Easy ASM Standard: N/A 39. Researchers studying a 5300-year-old mummy discovered in the 1990s think he may have been trying to use a fungus to treat his illnesses. Answer: True Difficulty: Easy
ASM Standard: 23, 26 40. Analyses of rRNA genes suggest that Archaea, Bacteria, and Eukarya evolved from a common ancestor. Answer: True Difficulty: Moderate ASM Standard: 5 41. The average size of a typical virus is approximately 100 nm. Answer: True Difficulty: Moderate ASM Standard: N/A 42. When a scientific name is used repeatedly, both the genus and species must always be written out in full to avoid confusion. Answer: False Difficulty: Moderate ASM Standard: N/A 43. Taenia saginata is a type of fungus that causes disease. Answer: False Difficulty: Moderate ASM Standard: 23 Matching 44. Match each type of microbiological tool with the best definition. A. loop i. tool used to transfer microbes from one location to another B. media ii. liquid, solid, or gel that contains nutrients to aid microbial growth C. microincinerator iii. tool used to sterilize equipment D. Petri plate iv. container used to grow microbial cultures Answers: A. i., B. ii., C. iii., D. iv. Difficulty: Easy ASM Standard: 36 45. Match the bacterial shape with the illustration.
(credit micrograph “i”: modification of work by Janice Haney Carr, Centers for Disease Control and Prevention; credit micrograph “iii”: modif ication of work by Centers f or Disease Control and Prevention)
Answers: A. v., B. i., C. iv., D. iii., E. ii. Difficulty: Easy ASM Standard: 34 46. Match each type of microbe with the best description. A. algae i. a very broad, informal grouping of organisms that do not fit into other eukaryotic kingdoms and that may be photosynthetic or nonphotosynthetic B. fungi ii. a diverse, informal subgroup of organisms that may move using cilia, flagella, or pseudopodia C. protists iii. a group of photosynthetic organisms with cellulose cell walls D. protozoa iv. a group of nonphotosynthetic organisms that usually have cell walls containing chitin Answers: A. iii., B. iv., C. i., D. ii. Difficulty: Moderate ASM Standard: 2 47. Match each subfield of microbiology with the most appropriate example. A. bacteriology i. the study of how antibodies are released in response to a pathogen B. immunology ii. the study of how fungi cause disease in plants C. mycology iii. the study of the classification of bacilli D. parasitology iv. the study of how to reduce the rate of guinea worm infections E. protozoology v. the study of heterotrophic protists
Answers: A. iii., B. i., C. ii., D. iv., E. v. Difficulty: Moderate ASM Standard: 23 48. Match each taxonomic group with its domain. You will use some options more than once.
A. algae i. Archaea B. halophiles ii. Bacteria C. helminths iii. Eukarya D. spirochetes Answers: A. iii., B. i., C. iii., D. ii. Difficulty: Moderate ASM Standard: 2 49. Match each causative agent with the associated classification. A. Dracunculus medinensis i. protist B. Ebola ii. fungus C. Giardia lamblia iii. helminth D. yeast iv. virus Answers: A. iii., B. iv., C. i., D. ii. Difficulty: Difficult ASM Standard: 23 Fill in the Blank 50.
was a Greek physician who posited that natural causes, not supernatural forces, caused disease. Answer: Hippocrates Difficulty: Easy ASM Standard: 23
51.
is the science of identifying, naming, and classifying living organisms. Answer: Taxonomy Difficulty: Easy ASM Standard: N/A
52. Fermentation by yeast produces ethanol and gas. Answer: carbon dioxide Difficulty: Moderate ASM Standard: 11, 26
53. Carl Woese and George Fox sequenced and analyzed wide range of organisms to build their phylogenetic tree. Answer: rRNA (or ribosomal RNA)
from a
Difficulty: Moderate ASM Standard: 4, 5 54. The archaebacteria are now called . Answer: Archaea Difficulty: Moderate ASM Standard: N/A 55. The genus of Halobacterium salinarum is . Answer: Halobacterium Difficulty: Easy ASM Standard: N/A 56. is the standard reference book that provides guidance onidentifying and classifying prokaryotes. Answer: Bergey’s Manual of Determinative Bacteriology Difficulty: Moderate ASM Standard: 34 57. There are nanometers in 520 meters. Answer: 520,000,000,000 Difficulty: Moderate ASM Standard: 29 58. The thermophilic genus Thermoproteus includes extremophiles classified in the domain . Answer: Archaea
Difficulty: Difficult ASM Standard: 5 59. The cytoplasmic extensions used by some protists to move are called . Answer: pseudopods Difficulty: Moderate ASM Standard: N/A Short Answer
60. What is horizontal gene transfer? Sample Answer: Horizontal gene transfer is the transfer of genetic material between two organisms that are not related as parent and offspring. Difficulty: Easy ASM Standard: 2 61. How are newly discovered organisms named? Sample Answer: Newly discovered organisms are usually given names that describe their characteristics and/or that honor a particular individual. The names are generally Latin, Greek, or English. Difficulty: Easy ASM Standard: 5 62. How do protozoa move? Sample Answer: Protozoa can move using structures such as pseudopods, flagella, and cilia. They may also be carried by the water in which they live. Difficulty: Easy ASM Standard: N/A 63. Why are formal scientific names based on a standardized system more useful than simple names that just describe characteristics, such as “orange cat-like animal”? Sample Answer: Organisms may have similar characteristics, especially in closely related species. By having a formal naming system, it is possible to clearly distinguish organisms so that people around the world can identify exactly which organism is being discussed.
Difficulty: Moderate ASM Standard: N/A 64. What are at least four types of products made using fermentation? Sample Answer: Fermentation is used to make alcoholic products, cheese, yogurts, pickled vegetables, and bread. Difficulty: Easy ASM Standard: 11, 23, 26 65. What is the Hippocratic Oath? Sample Answer: The Hippocratic Oath is an oath taken by new doctors to pledge their willingness to follow certain ethical guidelines, such as avoiding causing harm to their patients. Difficulty: Moderate ASM Standard: N/A31
66. Which famous scientist developed a vaccine for rabies? Sample Answer: Louis Pasteur developed a vaccine for rabies.
Difficulty: Moderate ASM Standard: 14, 23 67. Why is most milk pasteurized before it is sold? Sample Answer: Pasteurization helps reduce the number of microbes associated with spoilage and disease, keeping milk safe to drink longer than if it is not pasteurized.
Difficulty: Moderate ASM Standard: 14, 23 68. What are helminths and why are they medically important? Sample Answer: Helminths are worms. They are eukaryotes. They can be human parasites.
Difficulty: Moderate ASM Standard: 14, 23 69. Why is it often preferable to use a microincinerator rather than a Bunsen burner? Sample Answer: Bunsen burners have an open flame, whereas microincinerators do not; therefore, it is safer to use a microincinerator. Difficulty: Moderate ASM Standard: 14, 36 70. How do scientists decide how to organize organisms in a phylogenetic tree? Sample Answer: Phylogenies show evolutionary relationships. To develop a phylogenetic tree, scientists examine a variety of characteristics, including biochemical, morphological, and genetic characteristics, to determine the most likely relationships between organisms. Genetic data are especially important in determining these relationships in modern phylogenetic trees. Difficulty: Moderate ASM Standard: 5 71. What is the difference in how DNA is stored within the cells of prokaryotes versus eukaryotes? Sample Answer: Eukaryotes have a true membrane-bound nucleus and prokaryotes do not.
Difficulty: Moderate ASM Standard: 9
72. What does it m ean to say that som e photosynthetic bacteria, including som e green sulfur bacteria, are anoxygenic? Consider the word parts in “anoxygenic” if you are not sure. Sample Answer: Anoxygenic means that they do not generate oxygen.
Difficulty: Difficult ASM Standard: 11 73. Who published Systema Naturae and what did it present? Sample Answer: Systema Naturae was published by Carolus Linnaeus to present his taxonomic system. Difficulty: Difficult ASM Standard: N/A 74. Of the three domains, which is/are known to contain some human pathogens? Sample Answer: Bacteria and Eukarya contain some species that are human pathogens. No known archaeal pathogens have been identified. Difficulty: Moderate ASM Standard: 23 Brief Essay Essay Question Rubric RATING Failing Criteria for evaluati on
Answer does not provide an argument. Answer contains inaccuracies. Writing is poor and contains numerous grammatical mistakes and misspellings.
Below Average Answer fails to provide examples to support an argument. Writing is poor and grammatical errors are common. Answer is somewhat incoherent.
Competent
Advanced
Answer provides an argument with one or two examples that support it. Writing is acceptable for the college level but may contain one or two grammatical mistakes or misspellings.
Answer clearly provides an argument with two or more excellent examples that support it; student makes the argument clearly and eloquently. Answer is well organized and free of grammatical errors and misspellings. 3
0 1 2 POINT VALUE Assume rating/grading scale for the question ranges from 0 to 3 points.
75. Explain why some scientists think that it may be more appropriate to describe a “web of life” instead of a “tree of life.” Answer: Student answers will vary but should include components of the following. A tree suggests straightforward pathways of evolution from one branch to another. Because horizontal gene transfer is common, this does not fully represent the complexity involved in evolution. A web would better show ways genes can be transferred from one taxonomic group to another. Difficulty: Moderate ASM Standard: 5 76. Halobacterium salinarum is classified in the domain Archaea. Why does its name suggest it is a bacterium? This answer is not in the textbook chapter, so you should speculate based on your understanding of taxonomy. Answer: Student answers will vary but should include the following. This species was identified before the domain Archaea was recognized. As a result, it was previously considered a bacterium and given a bacterial name. Difficulty: Moderate ASM Standard: N/A 77. Consider the phylogenetic tree below. Explain how it shows the relationships between Bacteria, Archaea, and Eukarya, and their common ancestor. Of these three groups, which two are more closely related and how can you tell from the figure?
(credit: modification of work by Eric Gaba) Answer: Student answers will vary but should include the following. The lines leading to Bacteria, Archaea, and Eukarya branch from the same root, meaning they all share a common ancestor. Archaea and Eukarya branch more closely together than either branches with
Bacteria, suggesting that they diverged from each other more recently than they diverged from a common ancestor that had previously branched from Bacteria.
Difficulty: Difficult ASM Standard: 5 78. In the textbook chapter, there is information about efforts to eradicate the guinea worm. What are some factors that have allowed these efforts to be relatively successful, with only 126 cases reported in 2014, compared with efforts to eradicate other diseases such as hantavirus, carried by rodents, and rabies, carried by a variety of wild animals?
Answer: Student answers will vary but should include components of the following. Guinea worm is transmitted in contaminated water. Thus, efforts to improve water sanitation can be very effective in reducing infections. Other diseases have different mechanisms of transmission. Diseases such as rabies are found in wild animals and it would be difficult to treat or vaccinate all infected animals. Difficulty: Difficult ASM Standard: 14, 23, 31
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Chapter 2: How We See the Invisible World * = Correct answer Multiple Choice 1. Which term is used to refer to a wave’s rate of vibration? A. amplitude B. frequency* C. trough D. wavelength Difficulty: Easy ASM Standard: N/A 2. On the figure, which letter represents a refracted ray of light?
A. A B. B C. C D. D* Difficulty: Easy ASM Standard: N/A 3. On the electromagnetic spectrum, which type of wave has the shortest wavelength? A. cosmic ray* B. infrared ray C. ultraviolet ray D. visible light Difficulty: Moderate ASM Standard: N/A 4. Dyes are often used during microscopy to increase which of the following? A. contrast* B. magnification
C. motility D. resolution Difficulty: Easy ASM Standard: 32 5. Which of the following was the first to use the term “cells”? A. Robert Hooke* B. Robert Koch C. Carolus Linnaeus D. Antonie van Leeuwenhoek Difficulty: Easy ASM Standard: N/A 6. Which of the following is the typical magnification of an object viewed using a 10× ocular lens and a 100× objective lens on a brightfield microscope? A. 1× B. 10× C. 100× D. 1000×* Difficulty: Moderate ASM Standard: 32 7. Most modern microscopes have two eyepieces, meaning that they are which of the following? A. binocular* B. monocular C. oil immersion D. trinocular Difficulty: Easy ASM Standard: 32 8. An annular stop is used for which type of microscopy? A. confocal B. darkfield C. fluorescence D. phase contrast* Difficulty: Easy ASM Standard: 32 9. Which of the following is the specific name for a stain that colors the background but not the specimen?
A. acid-fast stain B. counterstain C. differential stain D. negative stain* Difficulty: Easy ASM Standard: 32 10. Which type of microscopy would work best for viewing internal cell structures? A. atomic force microscopy B. scanning electron microscopy C. scanning tunneling microscopy D. transmission electron microscopy* Difficulty: Moderate ASM Standard: 32 11. The Gram-staining procedure is best described as which of the following? A. complex staining B. differential staining* C. negative staining D. simple staining Difficulty: Easy ASM Standard: 32 12. When there is a substantial difference in refractive index between two materials, which of the following describes what will happen to light passing from one material to the other? A. It will fail to be refracted. B. It will undergo a large amount of refraction.* C. It will undergo a small amount of refraction. D. It will undergo a variable amount of refraction. Difficulty: Moderate ASM Standard: N/A 13. In microscopy, the focal length refers to which of the following? A. a description of the wavelength needed for an image to be in focus B. a measure of the amount of refraction produced by a lens C. a measure of the thickness of the lens needed for an image to be in focus D. the distance to the image point (at which all light entering a lens is parallel)* Difficulty: Moderate ASM Standard: 32 14. Which of the following are pigments used in microscopy to absorb and reflect light? A. chromatographs
B. chromophores* C. oilophores D. photophores Difficulty: Easy ASM Standard: N/A 15. Negative staining is the standard approach used to visualize which structure(s)? A. capsules* B. endospores C. flagella D. nucleoid regions Difficulty: Moderate ASM Standard: 6, 32 16. Which is a standard mordant used in flagella staining? A. basic fuchsin B. iodine C. safranin D. tannic acid* Difficulty: Moderate ASM Standard: 6, 32 17. Which of the following pairs are common acid-fast staining techniques? A. Gram and Kinyoun B. negative and Schaeffer-Fulton C. Ziehl-Neelsen and Kinyoun* D. Ziehl-Neelsen and Schaeffer-Fulton Difficulty: Moderate ASM Standard: 32 18. Which is the primary stain used in the Ziehl-Neelsen technique? A. acid-alcohol B. carbolfuchsin* C. crystal violet D. methylene blue Difficulty: Moderate ASM Standard: 32 19. Which is the correct order of steps in Gram staining? A. crystal violet stain, ethanol decolorization, Gram’s iodine mordant, safranin counterstain B. crystal violet stain, Gram’s iodine mordant, ethanol decolorization, safranin counterstain*
C. ethanol stain, crystal violet rinse, safranin counterstain, Gram’s iodine mordant D. safranin stain, Gram’s iodine mordant, ethanol decolorization, crystal violet counterstain Difficulty: Easy ASM Standard: 32 20. It is important to fix bacterial smears on a slide for which of the following reasons? A. to attach them to the slide* B. to cause swelling of the cell to make interior structures more visible C. to enhance the uptake of stains D. to provide a nutrient medium to sustain the bacteria Difficulty: Easy ASM Standard: 32 21. Which of the following is not commonly used for chemical fixation? A. acetic acid B. ethanol C. glutaraldehyde D. iodine* Difficulty: Moderate ASM Standard: 32 22. Which of the following is not involved in preparing a bacterial slide for Gram staining? A. allowing the sample to dry on the slide B. fixing the specimen to the slide C. placing a smear on the slide D. preparing a wet mount* Difficulty: Moderate ASM Standard: 32 23. Which of the following most specifically refers to stains with positively charged chromophores? A. acid-fast dyes B. acidic dyes C. basic dyes* D. positive dyes Difficulty: Moderate ASM Standard: 32 24. Which of the following most specifically refers to a stain that dyes a specimen rather than the background? A. counterstain
B. mordant C. negative stain D. positive stain* Difficulty: Moderate ASM Standard: 32 25. Which of the following describes the difference between the Ziehl-Neelsen and Kinyoun acid-fast staining techniques? A. The Ziehl-Neelsen technique uses a counterstain and the Kinyoun technique does not. B. The Ziehl-Neelsen technique uses an acidic dye and the Kinyoun technique does not. C. The Ziehl-Neelsen technique uses heat and the Kinyoun technique does not.* D. The Ziehl-Neelsen technique uses two dyes and the Kinyoun technique does not. Difficulty: Moderate ASM Standard: 32 26. Which of the following described the difference between gram-positive and gram-negative cells that causes them to stain differently after Gram staining? A. Gram-positive cells have a mycolic acid layer in their cell walls that holds in stain, whereas gram-negative cells lack this layer. B. Gram-positive cells have capsules and gram-negative cells have S layers. C. Gram-positive cells have thicker cell membranes than gram-negative cells. D. Gram-positive cells have thicker peptidoglycan layers in their cell walls than do gramnegative cells.* Difficulty: Moderate ASM Standard: 7, 32, 34, 36 27. Which of the following would not potentially cause a gram-positive cell to appear gramnegative after Gram staining? A. counterstaining with crystal violet instead of safranin* B. exposing the cells to ethanol for too long C. using older bacterial cultures D. using safranin as a primary stain Difficulty: Moderate ASM Standard: 32, 34, 36 28. Which of the following does not cause the probe to move up and down above the specimen in atomic force microscopy? A. chemical bonding B. electrostatic forces C. van der Waals forces D. variations in current*
Difficulty: Difficult ASM Standard: 32 29. Quantum tunneling of electrons is important in the mechanism underlying which microscope type? A. AFM B. SEM C. STM* D. TEM Difficulty: Moderate ASM Standard: 32 30. Which of the following is the chemical in some bacterial cells’ walls that makes themresist decolorization after acid-fast staining? A. acetic acid B. mycolic acid* C. peptidoglycan D. phospholipid Difficulty: Moderate ASM Standard: 32 31. Gram staining is useful for bacterial identification. Which of the following is another way it is most useful? A. Knowing Gram staining results allows a researcher to know which organisms abacterium can infect. B. Knowing Gram staining results allows a researcher to select the appropriate growth medium for optimal bacterial growth. C. Knowing Gram staining results is helpful in choosing an effective antibiotic.* D. Knowing Gram staining results is helpful in understanding a bacterium’s metabolic requirements. Difficulty: Difficult ASM Standard: 7, 23 32. Which of the following is not true regarding capsule staining? A. Capsules are typically stained using basic dyes.* B. Capsule staining does not require heat fixation in advance. C. Capsule staining requires careful selection of a stain that can stain the capsule itself. D. Capsule staining typically involves negative staining. Difficulty: Difficult ASM Standard: 7, 23 33. Because endospores are difficult to stain, which of the following is generally needed?
A. Heat must be used to make the endospore take up stain. B. Mycolic acid must be added to encourage the endospore to take up stain. C. Negative staining must be used to stain endospores because they do not absorb stain.* D. The cells must be cooled to make the endospore more brittle prior to staining. Difficulty: Difficult ASM Standard: 7, 32 34. When endospores are stained using the Schaeffer-Fulton method, which of the following correctly describes how they appear after staining? A. The endospore appears green within a pink cell, because only the endospore retained the primary stain.* B. The entire cell appears green because the endospore surrounds all the vegetative material. B. The entire cell appears pink because the endospore surrounds all the vegetative material. C. The entire cell appears pink except for a clear area representing the endospore. Difficulty: Moderate ASM Standard: 6, 7, 32 35. Specimens for TEM are prepared by doing which of the following? A. dehydrating the specimen in ethanol and then coating it in a material that will repel electrons B. sputter coating with a substance such as gold to repel electrons C. using an ultramicrotome to cut very thin sections from samples embedded in plastic resin* D. using chemical fixation, followed by standard staining techniques such as the Gram stain Difficulty: Difficult ASM Standard: 32 True/False 36. In fluorescence, emitted photons have the same amount of energy as absorbed photons. Answer: False Difficulty: Easy ASM Standard: N/A 37. A microscope with very high magnification and low resolution would allow you toclearly see small structures. Answer: False Difficulty: Easy ASM Standard: 6 38. The difference between a simple microscope and a compound microscope is that the latter only has one lens.
Answer: False Difficulty: Easy ASM Standard: N/A 39. Flagella staining is very useful for diagnostic purposes in medical settings. Answer: False Difficulty: Moderate ASM Standard: 7, 32 40. The transmission electron microscope and scanning electron microscope produce very similar images, but the former can be show three-dimensional external structures. Answer: False Difficulty: Moderate ASM Standard: 6, 32 41. Differential interference contrast microscopy produces three-dimensional images of specimens. Answer: True Difficulty: Moderate ASM Standard: 32 42. During specimen preparation for transmission electron microscopy, the specimensare dehydrated in alcohol and embedded in plastic resin. Answer: True Difficulty: Difficult ASM Standard: 32 43. In atomic force microscopy, the movement of the probe tip is determined using Hooke’slaw of elasticity. Answer: True Difficulty: Difficult ASM Standard: 32 Matching 44. Match each term with the best definition. A. amplitude i. electromagnetic radiation within certain parameters B. frequency ii. the height of a wave peak or depth of a wave trough C. visible light iii. the rate of vibration of a wave D. wavelength iv. the distance between two wave peaks
Answers: A. ii., B. iii., C. i., D. iv. Difficulty: Easy ASM Standard: N/A 45. Match each term with the best definition. A. absorbance i. Light waves change direction when they enter a new medium. B. diffraction ii. Two waves interact. C. interference iii. A wave travels through something. D. refraction iv. A material captures light energy. E. transmission v. Light bends or scatters as it interacts with objects or openings. Answers: A. iv., B. v., C. ii., D. i., E. iii. Difficulty: Moderate ASM Standard: N/A 46. Match each type of microscope with a common use for that microscope type. A. brightfield i. commonly used clinically; helpful in distinguishing living from dead cells, finding molecules within a cell, and for immunostaining B. darkfield ii. widely used and easily available; used for examining common protists, bacteria, and tissues; stains are often needed C. fluorescence iii. uses an annular stop, refraction, and interference to produce relatively high-resolution images without stains D. phase contrast iv. used to examine an image produced with light that hits a specimen indirectly owing to the use of an opaque light stop; often used to view living microorganisms without stains E. two-photon v. often used to penetrate thick specimens, such as biofilms, with long-wavelength light Answers: A. ii., B. iv., C. i., D. iii., E. v. Difficulty: Difficult ASM Standard: 32 47. Match each type of microscopy with the best description. A. atomic force microscopy i. measures changes in current as a probe is moved at a constant height over a specimen B. scanning electron ii. measures variations in the height of a probe moving microscopy over the specimen; height variations occur to maintain a constant current C. scanning tunneling iii. yields images from electrons produced by an electron microscopy beam hitting the surface of a sputter-coated specimen D. transmission electron iv. produces images from electrons that pass through a microscopy very thin specimen, allowing internal structures to be visualized Answers: A. ii., B. iii., C. i., D. iv. Difficulty: Moderate
36. Tamiflu is a hemagglutinin inhibitor commonly used against influenza virus. Answer: False Difficulty: Easy ASM Standard: 14 37. Isoniazid is an antimetabolite that can be used to treat mycobacterial infections. Answer: True Difficulty: Moderate ASM Standard: 14 38. Individuals cannot have MRSA as part of their normal flora ormicrobiota. Answer: False Difficulty: Moderate ASM Standard: 14, 23 39. The Kirby-Bauer disk diffusion assay can distinguish between bacteriostatic and bactericidal agents. Answer: False Difficulty: Easy ASM Standard: 36 40. The Etest combines both the Kirby-Bauer disk diffusion assay and the minimum inhibitory concentration dilution assay to determine the effectiveness of an antimicrobial compound. Answer: True Difficulty: Easy ASM Standard: 36 41. Due to concern of antimicrobial resistance, the number of antimicrobial drugs approved by the FDA has increased since the 1980s. Answer: False Difficulty: Easy ASM Standard: 3, 14, 26 Matching 42. Match the antimicrobial agent to its mode of action. A. chloramphenicol i. inhibits nucleic acid synthesis B. fluoroquinolone ii. inhibits the 30S ribosomal subunit C. penicillin iii. inhibits cell wall synthesis
D. tetracycline E. trimethoprim Answers: A. v., B. i., C. iii., D. ii., E. iv.
iv. acts as an antimetabolite v. inhibits the 50S ribosomal subunit
Difficulty: Easy ASM Standard: 7, 14 43. Match the antimicrobial agent to its mode of action. A. bacitracin i. inhibits cell wall synthesis B. diarylquinoline ii. inhibits nucleic acid synthesis C. isonicotinic acid hydrazide iii. disrupts cell membranes D. polymyxin iv. inhibits ATP synthase E. rifampin v. acts as an antimetabolite Answers: A. i., B. iv., C. v., D. iii., E. ii. Difficulty: Moderate ASM Standard: 7, 14 44. Match the antimicrobial agent to its mode of action. A. artemisinin i. competes with coenzyme Q for electrons B. atovaquone ii. interferes with heme detoxification C. imidazole iii. produces reactive oxygen species D. pentamidine iv. inhibits ergosterol synthesis E. quinoline v. affects DNA and RNA, and, therefore, protein production Answers: A. iii., B. i., C. iv., D. v., E. ii. Difficulty: Moderate ASM Standard: 14 45. Match the antiviral to the virus it is used to treat. A. acyclovir i. hepatitis C B. etravirine ii. HIV C. sofosbuvir iii. influenza D. zanamivir iv. herpes Answers: A. iv., B. ii., C. i., D. iii. Difficulty: Moderate ASM Standard: 14 Fill in the Blank 46. The microbial environment that has been investigated most thoroughly for the production of antimicrobial compounds is ? Answer: soil Difficulty: difficult
ASM Standard: 7, 14, 22 47. At the hospital, the fist antimicrobial drug given, especially when the pathogen is not yet known, is often a -spectrum drug. Answer: broad Difficulty: Easy ASM Standard: 14, 26 48. Ampicillin and amoxicillin are Answer: semisynthetic
penicillins.
Difficulty: Easy ASM Standard: 14, 26 49. Penicillin inhibits the reaction of cell wall synthesis. Answer: transpeptidation (also accept cross-linking) Difficulty: Difficult ASM Standard: 7, 14 50. Most antifungal agents target Answer: ergosterol
, which is found in the fungal cell membrane.
Difficulty: Easy ASM Standard: 7, 14 51. Artemisinin and quinolines are antimicrobials used against Answer: malaria
.
Difficulty: Easy ASM Standard: 14 52. Carbapenem-resistant gram-negative bacteria are common in Answer: health-care settings (also accept nosocomial infections)
.
Difficulty: Moderate ASM Standard: 3, 14, 23 53. The is the lowest concentration of a drug that inhibits visible growth in culture. Answer: minimum inhibitory concentration (MIC) Difficulty: Easy ASM Standard: 36
54. The is the lowest concentration of a drug that kills at least 99.9% of the starting inoculum. Answer: minimum bactericidal concentration (MBC) Difficulty: Easy ASM Standard: 36 55. A group of pathogens called demonstrate cross-resistance. Answer: ESKAPE
pathogens are multidrug resistant microbes that
Difficulty: Moderate ASM Standard: 3, 14, 22, 23 Short Answer 56. Examine the two growth curves shown below. Identify which drug is the bactericidal agent and which is the bacteriostatic agent. Briefly state how you arrived at your answer.
Sample Answer: Agent A is bacteriostatic. These agents inhibit but do not kill. When the agent is removed, growth resumes. Agent B is bactericidal. These agents kill the target bacteria, as seen in the graph. Difficulty: Moderate ASM Standard: 14 57. What is the definition of dosage? Sample Answer: Dosage is the amount of a drug given during a certain time period. Difficulty: Easy ASM Standard: 26 58. What should be considered when determining dosage?
Sample Answer: Answers can include the following: what the pathogen is, for how long the infection or disease has occurred, the age and body mass of the patient, the half-life of the drug, potential adverse effects resulting from prolonged use, the concentrations at which the drug becomes toxic to the patient. Difficulty: Easy ASM Standard: 26, 27 59. What should be considered when determining a route of administration? Sample Answer: Health-care providers should first consider whether the drug needs to go inside of the body to treat the infection. If the patient has a skin infection, then a topical medication could be prescribed. If patient has colitis, rectal therapy (i.e., suppositories) could be used. If the drug can be taken orally, will the drug still be effective after exposure to the acidity of the stomach? Can the drug be absorbed by the gastrointestinal tract to enter the bloodstream? If not, intravenous or intramuscular injection could be given. Difficulty: Easy ASM Standard: 26 60. Give an example of an antagonistic drug interaction. Sample Answer: Antacids will increase the pH of the stomach and may negatively impact the absorption of an antimicrobial. Difficulty: Easy ASM Standard: 26 61. A culture of E. coli is currently in the exponential phase. It is exposed to penicillin. Whatwill happen to the bacteria as they continue to grow and divide in the presence of this antibiotic? Briefly explain your answer. Sample Answer: Penicillin inhibits peptidoglycan cross-linking (transpeptidation reaction). As a result, the bacteria will elongate and then pop, like overfilled balloons, because the integrity of the cell wall is compromised. A video of this can be seen at: https://www.youtube.com/watch?v=UjLmf-cVcMw Difficulty: Moderate ASM Standard: 7, 14 62. What are the three antibiotics typically found in Neosporin? Sample Answer: bacitracin, neomycin, polymyxin B Difficulty: Easy ASM Standard: 14 63. Why is chloramphenicol rarely used on humans? Sample Answer: It can result in serious complications such as lethal gray baby syndrome, the suppression of bone marrow production, and anemia.
Difficulty: Easy ASM Standard: 26 64. Why are helmiths, fungi, and protozoan pathogens difficult to treat with antimicrobial agents? Sample Answer: They have eukaryotic cells, like their hosts. Drugs that inhibit eukaryotic cell processes could have a negative impact on the host cells as well. Thus, it is difficult to develop antimicrobial agents that are selectively toxic for these types of microbes Difficulty: Moderate ASM Standard: 14 65. Some bacteria have a very low level of resistance to antibiotics, while others have a high level of resistance. (a) In terms of natural selection, explain why scientists believe antibiotics should be given only when necessary. (b) What can be done to prevent the further spread of antibiotic resistance? Sample Answer: (a) As we continue to use antibiotics, we are selecting for microorganisms that are more resistant to our antimicrobial drugs. As a result, drug-resistant microorganisms will be more prevalent and will be harder to target. (b) Doctors should only prescribe antibiotics to treat bacterial infections when needed. Patients should also finish their medication (even if they feel better after only a few days into treatment) to kill off all of the pathogen. Difficulty: Moderate ASM Standard: 3, 14, 26 66. What is the resistance mechanism for MRSA? Sample Answer: MRSA strains produce a penicillin-binding protein that has a low affinity for β-lactam antibiotics (an example of target modification). Difficulty: Moderate ASM Standard: 3, 14 67. How do VISA and VRSAdiffer? Sample Answer: VISA and VRSA strains of Staphylococcus aureus differ in their levels of resistance to vancomycin and in their mechanisms of resistance. VISA has intermediate resistance to vancomycin. Its resistance mechanism involves increasing vancomycin targets (peptidoglycan subunits, D-Ala–D-Ala peptide off NAM). VRSA is resistant to vancomycin and its resistance mechanism is to change the target (peptidoglycan subunits, changing the DAla–D-ala peptide to D-Ala–D-Lac or remove one of the D-Ala amino acids). See image below.
Difficulty: Difficult ASM Standard: 3, 14 68. How could bacteria develop resistance to sulfa drugs (sulfonamide)? Be sure to state a possible resistance mechanism. Sample Answer: Bacteria can become resistant to antimicrobial agents through spontaneous mutations, transposons, or horizontal gene transfer. There are various answers for the second part of the question. Examples can include target modification of the metabolic enzyme to which sulfa drugs bind, target overproduction of this enzyme, and enzymatic bypass to produce dihydrofolic acid using an alternate pathway. Difficulty: Difficult ASM Standard: 2, 3, 14 69. What is the difference between MIC and MBC? Sample Answer: The MIC is the lowest concentration of a drug that inhibits visible growth in culture, whereas the MBC is the lowest concentration of a drug that kills at least 99.9% of the starting inoculum. Difficulty: Easy ASM Standard: 36 70. An MIC assay is shown below. Tube A contains vancomycin at a concentration of 25 mg/mL. The serial dilutions performed are shown. Then Staphylococcus aureus was inoculated into each tube. The tubes were then incubated for 24 hours. After 24 hours, growth was observed only in tubes E and F. From this experiment, identify which tube contains the MIC and calculate the MIC of vancomycin for S. aureus.
Sample Answer: The MIC would be tube D because it contains the lowest concentration that inhibited growth. Tube D has a 10–4 dilution, so the concentration is 25 mg/mL × 10-4 = 2.5 µg/mL. Difficulty: Difficult ASM Standard: 28b, 29a, 36 Brief Essay Essay Question Rubric RATING Failing Criteria for evaluati on
Answer does not provide an argument. Answer contains inaccuracies. Writing is poor and contains numerous grammatical mistakes and misspellings.
Below Average Answer fails to provide examples to support an argument. Writing is poor and grammatical errors are common. Answer is somewhat incoherent.
Competent
Advanced
Answer provides an argument with one or two examples that support it. Writing is acceptable for the college level but may contain one or two grammatical mistakes or misspellings.
Answer clearly provides an argument with two or more excellent examples that support it; student makes the argument clearly and eloquently. Answer is well organized and free of grammatical errors and misspellings.
0 1 2 3 POINT VALUE Assume rating/grading scale for the question ranges from 0 to 3 points. 71. (a) State the five general targets of antibacterial compounds and give an example of an antibiotic that acts on each target. (b) Why are viruses not affected by antibacterial compounds? Answer: Student answers will vary but should include the following.
(a) The five targets and examples of each are shown below.
(b) Viruses do not have these targets. They do not have a cell wall, a plasma membrane, ribosomes, metabolism, or enzymes for DNA replication. Although some will have enzymes for RNA replication, antibiotics are ineffective against them. Difficulty: Easy ASM Standard: 7, 14, 26 72. (a) State any four mechanisms of antibiotic resistance that bacteria use. (b) For each multidrug-resistant microbe listed below, state specifically the mechanism it uses to resist the action of the antibiotic. • MRSA • VISA • VRSA • carbapenem resistance in Pseudomonas aeruginosa Sample Answer: Student answers will vary but should include the following. (a) The four mechanisms are efflux pumps, drug inactivation, decreased/blocked penetration, and target modification. (b) Mechanisms used by each antibiotic-resistant bacterium: • MRSA strains produce a penicillin-binding protein that has a low affinity forβlactam antibiotics (an example of target modification). • VISA’s resistance mechanism is to increase vancomycin targets (peptidoglycan subunits, D-Ala–D-Ala peptide off NAM; an example of target modification)
• •
VRSA is resistant to vancomycin because of the modification of the peptide component of peptiglycan subunits such that they can no longer bind to vancomycin, an example of target modification. Carbapenem resistance in P. aeruginosa is due to a decrease in the amount of porins on its outer membrane (because it is gram negative), thus reducing the amount of carbapenem that enters the cell (decreased penetration).
Difficulty: Moderate ASM Standard: 3, 7, 14, 22, 26 73. Explain the treatment of HIV, answering the following four questions: What class of virus is HIV? Briefly describe the life cycle of HIV. In terms of the viral life cycle, why is it difficult to treat HIV? In terms of the viral life cycle, what type of inhibitor drugs could be used to treat HIV? Sample Answer: Student answers will vary but should include the following. HIV is a retrovirus. It is an enveloped virus that contains spike proteins (gp120 and gp41) that recognize and bind to CD4-positive T cells. The virus binds to the CD4 receptor. After entry, the viral RNA is reverse transcribed into DNA, using reverse transcriptase. The DNA is then integrated into the chromosome. The viral DNA is then transcribed into viral RNA and synthesis of the HIV capsid occurs. The capsid proteins come to the cell surface where HIV assembles and buds off the host cell. It is difficult to treat HIV for several reasons. A drug cannot target the host cell because CD4 T cells are necessary for our immune system. A drug cannot be used to target the DNA because the DNA integrates into the host cell genome. HIV's reverse transcriptase introduces mutations, so drug resistance is common with HIV. Protease inhibitors could be used as long as they target only the viral protein. The use of proteases could damage the host cell and the host. Inhibitors that could be used to disrupt the life cycle of HIV can include fusion inhibitors to prevent initial binding of HIV to the cell. AZT, a reverse transcriptase, or an integrase inhibitor can prevent viral DNA from integrating into the chromosome. Difficulty: Moderate ASM Standard: 3, 7, 10, 14, 18 74. Lori has a very bad sore throat. She goes to the doctor and is told that it is not a bacterial infection. (a) The doctor then prescribes an antibiotic for her to take. Should the doctor have given Lori this prescription? Why would the doctor give such a treatment? (b) Lori gets well! A week goes by and then the sore throat comes back. This time the doctor suspects strep throat. A culture is taken and sent to the lab to confirm, using blood agar, that she has strep throat. The lab then performs a Kirby-Bauer disk diffusion assay using antibiotics A through D. The results are shownbelow:
(i) (ii)
Based on the results shown above, which antibiotic worked best? Circle any antibiotic-resistant colonies. If there are any antibioticresistant bacteria, how could they have arisen? (c) Lori takes the antibiotic as prescribed and a week later returns to the doctor. Apparently the concentration being used is not working. Should the doctor just give a higher concentration of antibiotic? What problems may arise from this action? Sample Answer: Student answers will vary but should include the following. (a) Antibiotics target bacteria. In that sense, the doctor shouldn’t have prescribed an antibiotic. The doctor may prescribe an antibiotic not to cure but to help prevent a bacterial infection that may result because of the lowered immunity of the sick person. This should not be done because it can lead to an increase in antibiotic resistance. Heath- care providers often feel pressured to prescribe antibiotics, so he or she may have felt that way. (b) (i) D worked best. (ii) Several colonies were resistant to A (see diagram below). They could have arisen from spontaneous mutations, transposons, or the mechanisms of horizontal gene transfer (i.e., transformation, transduction, conjugation).
(c) Exposure to antibiotics provides selective pressure, which makes the surviving bacteria more likely to be resistant. Giving higher concentrations provides more selective pressure, potentially resulting in more resistant bacteria and higher MIC concentrations required to eradicate the infection. Difficulty: Difficult ASM Standard: 2, 3, 14, 22, 26, 28b, 36 This file is copyright 2017, Rice University. All rights reserved.
Chapter 15: Microbial Mechanisms of Pathogenicity * = Correct answer Multiple Choice 1. Which of the following would be considered a symptom? A. blood pressure reading of 150/90 mm Hg B. body ache and chills* C. fever of 39 C D. heart rate of 120 bpm Difficulty: Easy ASM Standard: N/A 2. Which of the following would be considered a sign? A. blurry vision B. body ache and chills C. burning sensation during urination D. gross hematuria (visible presence of blood in urine)* Difficulty: Easy ASM Standard: N/A 3. Which of the following is an example of a nosocomial disease? A. acquiring Giardia while drinking from a stream during a camping trip B. acquiring Listeria after eating at a public restaurant C. acquiring MRSA after touching a locker door handle after an already infected individual did so D. obtaining a Pseudomonas respiratory infection during a recent visit to the hospital* Difficulty: Easy ASM Standard: 23 4. Sickle cell anemia can be classified as which type of disease? A. idiopathic B. infectious, communicable C. infectious, noncommunicable D. noninfectious* Difficulty: Easy ASM Standard: N/A 5. Which of the following is not a zoonotic disease? A. rabies B. Rocky Mountain spotted fever
C. typhoid* D. yellow fever Difficulty: Easy ASM Standard: 23 6. What period of disease describes when the patient begins to feel general signs and symptoms? A. incubation period B. period of convalescence C. period of illness D. prodromal period* Difficulty: Easy ASM Standard: 23 7. During which period of disease is a patient most susceptible to developing a secondary infection? A. incubation period B. period of convalescence C. period of decline* D. prodromal period Difficulty: Moderate ASM Standard: 23 Examine the graph shown below and then answer questions 8 and 9.
8. Examine the graph and determine the approximate ID 50 of the virus. A. 10 particles B. 5000 particles C. 13,000 particles* D. cannot be determined from the data collected Difficulty: Moderate ASM Standard: 10, 23, 28b, 29, 36
9. Examine the graph and determine the LD50 of the virus. A. 10 particles B. 5000 particles C. 13,000 particles D. cannot be determined from the data collected* Difficulty: Moderate ASM Standard: 23, 28b, 29, 36 10. Identify which pathogen is the least virulent on the basis of ID 50 . A. pathogen A with an ID 50 of 1000 cells* B. pathogen B with an ID50 of 50 cells C. pathogen C with an ID50 of 1 cell D. pathogenicity cannot be determined from ID 50 values Difficulty: Moderate ASM Standard: 23 11. Which of the following is the definition of pathogenicity? A. the ability of a microbial agent to cause disease* B. the ability of a microbial agent to cause infection C. the ability of a microbial agent to prevent disease D. the ability of a microbial agent to produce an antimicrobial compound Difficulty: Easy ASM Standard: 23 12. Which pathogen cannot pass the blood–placenta barrier and infect a fetus? A. Herpes simplex virus 1 B. Listeria monocytogenes C. Salmonella typhi* D. Toxoplasma gondii Difficulty: Moderate ASM Standard: 23 13. Which of the following is a common secondary fungal disease? A. giardiasis B. histoplasmosis C. oral thrush* D. syphilis Difficulty: Moderate ASM Standard: 23 14. Which statement properly describes how Salmonella typhi enters host cells?
A. S. typhi binds to receptors on host cells that cause endocytosis. B. S. typhi is not an intracellular pathogen. C. S. typhi secretes effector proteins that cause membrane ruffling.* D. S. typhi specifically invades phagocytic host cells. Difficulty: Difficult ASM Standard: 8, 13, 22, 23 15. Why are Pseudomonas aeruginosa infections difficult to treat? A. Because they are gram-positive bacteria, which are harder to treat. B. Because they form biofilms, which are difficult for antibiotics to penetrate.* C. Because they have a special endotoxin that degrades many antibiotics. D. Because we do not have any antibiotics that target P. aeruginosa. Difficulty: Easy ASM Standard: 13, 21, 22, 23 16. Which describes the condition in which blood contains actively dividing bacteria? A. bacteremia B. septicemia* C. toxemia D. viremia Difficulty: Easy ASM Standard: 13, 23 17. Molecular Koch’s postulates are used to identify which characteristic of pathogens? A. an effective treatment B. the ID 50 C. the LD 50 D. virulence factor genes* Difficulty: Moderate ASM Standard: 8, 23, 36 18. Hyaluronidase is which type of exoenzyme? A. glycohydrolase* B. nuclease C. phospholipase D. protease Difficulty: Easy ASM Standard: 22, 23 19. Intracellular pathogens, like Listeria and Rickettsia, produce which type of exoenzyme to aid in escaping the phagosome?
A. glycohydrolases B. nucleases C. phospholipases* D. proteases Difficulty: Moderate ASM Standard: 13, 22, 23 20. Which virulence factor, produced by Staphylococcus aureus, allows the bacterium tobe coated in fibrin that protects it from phagocytes? A. catalase B. coagulase* C. collagenase D. oxidase Difficulty: Moderate ASM Standard: 13, 22, 23 21. What is the toxic component of endotoxin? A. lipid A* B. the core oligosaccharide C. the O-antigen D. the peptidoglycan subunits Difficulty: Easy ASM Standard: 8 22. You are working in a hospital and have been asked to perform the LAL test (Limulus amebocyte lysate). After adding the amebocytes from the horseshoe crab to theserum, coagulation is not observed. What conclusion can you draw from this? A. The patient’s serum contains endotoxin.* B. The patient’s serum contains exotoxin. C. The patient’s serum does not contain endotoxin. D. No conclusion can be reached because the LAL test is not used for detection of toxins. Difficulty: Difficult ASM Standard: 28b, 36, 38 23. In the A-B toxin, which subunit is necessary for making the initial attachment to thehost cell? A. the A subunit B. the B subunit* C. Depending on the toxin, it could be either the A or B subunit. D. Neither, because A-B toxins do not function this way. Difficulty: Easy
ASM Standard: 23 24. An enterotoxin targets which type of cell? A. cardiac cells B. hepatic cells C. intestinal cells* D. respiratory cells Difficulty: Easy ASM Standard: 23 25. Which toxin inhibits the release of glycine and GABA at the neuromuscular junction, thus preventing the relaxation of muscles? A. anthrax B. botulinum C. diphtheria D. tetanus* Difficulty: Moderate ASM Standard: 23 26. Which is the target for the diphtheria toxin? A. charged tRNA molecules B. elongation factor 2* C. mRNA molecules D. the eukaryotic ribosome Difficulty: Difficult ASM Standard: 23 27. Which are the attachment sites for hemagglutinin spike proteins of influenza virus? A. CD4 receptors B. CD8 receptors C. heparan sulfate D. sialic acid* Difficulty: Easy ASM Standard: 10, 23 28. Which is the name of the toxin produced by species of Aspergillus that can cause liver cancer? A. aflatoxin* B. citrinin C. ochratoxin D. patulin
Difficulty: Moderate ASM Standard: 9, 23 29. The Panton-Valentine leukocidin from Staphylococcus aureus targets which cell type? A. intestinal epithelial cells B. neurons C. red blood cells D. white blood cells* Difficulty: Easy ASM Standard: 13, 22, 23 30. Which surface molecules do helminths commonly express that protect them from the host immune system? A. fibrins B. glycans* C. hemagglutinins D. proteases Difficulty: Easy ASM Standard: 9, 13, 23 True/False 31. The prodromal period is when the maximum number of pathogen particles or organisms are present in an infected host. Answer: False Difficulty: Easy ASM Standard: 23 32. All pathogens satisfy Koch’s postulates. Answer: False Difficulty: Moderate ASM Standard: 23 33. Facultative intracellular pathogens can reproduce both inside and outside host cells. Answer: True Difficulty: Easy ASM Standard: 13, 22, 23 34. The severity of disease depends only on the activity of the pathogen. Answer: False
Difficulty: Easy ASM Standard: 23 35. The normal flora and microbiota of an individual can cause disease. Answer: True Difficulty: Moderate ASM Standard: 23 36. All contacts with a pathogen will result in infection. Answer: False Difficulty: Difficult ASM Standard: 22, 23 37. Extracellular DNA from lysed host cells can function as a means of preventing the spreadof a pathogen in a host. Answer: True Difficulty: Moderate ASM Standard: N/A 38. Endotoxin is produced only by gram-negative bacteria. Answer: True Difficulty: Easy ASM Standard: 8 39. Giardia lamblia invades the intestinal mucosa, causing them to shrink and limitingtheir absorption of nutrients. Answer: False Difficulty: Moderate ASM Standard: 9, 23 40. Bacteria, fungi, and protozoa often use similar virulence factors and mechanisms of pathogenicity. Answer: True Difficulty: Moderate ASM Standard: 8, 9, 23 Matching 41. Match the disease nomenclature to its meaning. A. –derma i. cell destruction
B. –emia ii. thickened skin C. –itis iii. tumor formation D. –lysis iv. inflammation E. –oma v. blood Answers: A. ii., B. v., C. iv., D. i., E. iii. Difficulty: Easy ASM Standard: N/A 42. Match the type of infection to its proper description. A. focal i. The pathogen goes from one location to a second location. B. local ii. Asecond infection emerges due to killing of protective flora during antibiotic treatment. C. secondary iii. The pathogen spreads throughout the host. D. superinfection iv. The pathogen remains in one location. E. systemic v. Another disease-causing pathogen emerges after an initial infection. Answers: A. i., B. iv., C. v., D. ii., E. iii. Difficulty: Easy ASM Standard: 23 43. Match the bacterial toxin to its mechanism of action. A. botulinum i. inhibits host cell protein synthesis B. cholera ii. activates adenylate cyclase, resulting in higher levels of cAMP and loss of electrolytes leading to diarrhea C. diphtheria iii. inhibits glycine release to inhibit muscle relaxation D. tetanus iv. inhibits release of acetylcholine to inhibit muscle contraction. Answers: A. iv., B. ii., C. i., D. iii. Difficulty: Moderate ASM Standard: 23 44. Match the bacterial toxin to its mechanism of action. A. Clostridium perfringens α toxin i. inhibits host cell protein synthesis B. pneumolysin ii. overactivates immune system, leading to inflammation and toxic shock syndrome C. Shiga toxin iii. assembles into membrane pores, resulting in cell rupturing D. Streptococcus pyogenes mitogenic iv. degrades membrane phospholipids exotoxin Answers: A. iv., B. iii., C. i., D. ii. Difficulty: Difficult ASM Standard: 23 Fill in the Blank
45.
pathogens always cause disease. Answer: Primary (alternative answers: True, Frank) Difficulty: Easy ASM Standard: 23
46.
pathogens can cause disease when the host is immunocompromised. Answer: Opportunistic Difficulty: Easy ASM Standard: 23
47.
permit pathogens to cause disease. Answer: Virulence factors Difficulty: Easy ASM Standard: 8, 22, 23
48.
are molecules, receptors, or surface structures necessary for attachment to a host cell. Answer: Adhesins Difficulty: Moderate ASM Standard: 8, 23
49.
are anatomic locations where pathogens can pass into host tissue. Answer: Portals of entry Difficulty: Easy ASM Standard: 23
50. A(n) is a biological poison produced by certain pathogens. Answer: toxin Difficulty: Easy ASM Standard: 23 51.
are exotoxins that can trigger a cytokine storm. Answer: Superantigens Difficulty: Easy ASM Standard: 23
52.
is a yellowing of the skin and eyes due to the lysis of erythrocytes resulting from infection with either hepatitis B virus or Plasmodium falciparum.
Answer: Jaundice Difficulty: Easy ASM Standard: 23 53.
are extracellular structures in bacteria that are involved in conjugation and can be used as adhesins. Answer: Pili Difficulty: Easy ASM Standard: 8, 23
54. A(n) is when an influenza virus acquires a new hemagglutinin neuraminidase spike protein from another influenza virus coinfecting the same host cell. Answer: antigenic shift Difficulty: Moderate ASM Standard: 10, 18, 23 Short Answer 55. Explain the similarity and difference between iatrogenic and nosocomial diseases. Sample Answer: Both could occur in the hospital setting. However, iatrogenic diseases are the direct result of a medical procedure, whereas nosocomial diseases are simply acquired in a hospital setting. Difficulty: Easy ASM Standard: 23 56. Why are not all communicable diseases contagious? Sample Answer: Communicable diseases can be transmitted from person to person. How contagious it is depends upon how the pathogen is transmitted. For example, a sexually transmitted disease is contagious only between sexually active individuals. However, someone who is not sexually active would most likely not acquire the disease. Difficulty: Moderate ASM Standard: 23 57. Name three different types or classes of noninfectious diseases. Sample Answer: Any of the following are noninfectious diseases: inherited, congenital, degenerative, nutritional deficiency, endocrine, neoplastic, and idiopathic. Difficulty: Moderate ASM Standard: 23
58. On the axes below, sketch and identify the five periods of disease progression, and show the severity of symptoms at each stage.
Sample Answer: See below:
Difficulty: Moderate ASM Standard: 23 59. (a) Which part of the body does Helicobacter pylori colonize? (b) What is the virulence factor produced by H. pylori that allows it to survive in that location?
Sample Answer: H. pylori persists in the stomach by producing urease, which raises the pH of the stomach. Difficulty: Moderate ASM Standard: 13, 22, 23 60. Explain the similarity and difference between chronic and latent infections. Sample Answer: A chronic disease lasts for months or years. Latent diseases last for years, but are distinguished from chronic diseases by a lack of active replication during extended dormant periods. Difficulty: Moderate ASM Standard: 23 61. What is the parenteral route? Sample Answer: The parenteral route refers to any way into the body bypassing the skin and mucous membranes. Thus, it refers to routes into the body other than through the respiratory tract, gastrointestinal tract, or genitourinary tract. It typically it refers to entry into the host through breaks in the skin due to wounds, insect bites, animal bites, and needle pricks. Difficulty: Moderate ASM Standard: 23 62. (a) Explain what a capsule is and how it functions as a virulence factor. (b) Besides bacteria, do any pathogenic eukaryotic microorganisms produce a capsule? Sample Answer: The capsule is a type of glycocalyx. The glycocalyx is a coating of molecules external to the bacterial cell wall, typically made of sugars and/or proteins. The capsule is a highly organized type of glycocalyx. It acts as a virulence factor because it assists attachment of pathogens to a host and protects the pathogen against phagocytosis. Fungi and protozoa also produce capsules. Some helminths produce extracellular polysaccharide glycans that allow them to evade the immune system, functioning in that way like the capsules produced by other pathogenic microbes. Difficulty: Difficult ASM Standard: 8, 9, 13, 23 63. What are the four steps of pathogenesis? Sample Answer: exposure (contact), adhesion (colonization), invasion, infection Difficulty: Easy ASM Standard: 23 64. Describe two ways bacterial pathogens can initiate endocytosis into a nonphagocytic host cell.