Prokaryotic Diversity

Chapter 4: Prokaryotic Diversity Chapter 4: Prokaryotic Diversity * = Correct answer Multiple Choice 1. Which is the best example of a population? A. all the microbes living in a particular area B. all the microbes of a particular domain living in a particular area C. all the microbes of a single species living in a particular area* D. all the microbes living within the same host Difficulty: Moderate ASM Standard: 20 2. Microbial ecology is defined as the study of which of the following? A. competitive interactions between microbes B. cooperative interactions between microbes C. interactions between individuals of a single species D. interactions between microbial populations and their environment* Difficulty: Easy ASM Standard: 20 3. Which term best describes the relationship between pathogenic bacteria and humans? A. amensalism B. commensalism C. parasitism* D. predation Difficulty: Moderate ASM Standard: 23 4. Which of the following is not a class within the phylum Proteobacteria? A. Alphaproteobacteria B. Betaproteobacteria C. Deltaproteobacteria D. Omegaproteobacteria* Difficulty: Easy ASM Standard: N/A 5. Which of the following correctly characterizes Epsilonproteobacteria? A. They are atypical (not gram positive or gram negative). B. They are gram negative.* C. They are gram positive. Page 1 of 17 Chapter 4: Prokaryotic Diversity D. They are gram variable. Difficulty: Easy ASM Standard: 34 6. Which describes bacteria that require low concentrations of oxygen to survive (less than that in the current atmosphere)? A. facultative anaerobes B. microaerophiles* C. obligate aerobes D. obligate anaerobes Difficulty: Easy ASM Standard: 11, 22 7. Cyanobacteria produce which of the following? A. hydrogen sulfide gas B. large quantities of ammonia C. oxygen* D. sulfuric acid Difficulty: Easy ASM Standard: 11, 22 8. Which of the following bacterial groups is thought to be most closely related to the last universal common ancestor? A. Alphaproteobacteria B. cyanobacteria C. deeply branching bacteria* D. green filamentous bacteria Difficulty: Easy ASM Standard: 5 9. Which of the following is a phylum in Domain Archaea? A. Crenarchaeotae* B. Deinococcus C. Mycoplasma D. Thermotogae Difficulty: Easy ASM Standard: 5 10. Which genus contains the nitrogen-fixing bacteria that live in legume nodules? A. Bacillus B. Escherichia Page 2 of 17 Chapter 4: Prokaryotic Diversity C. Rhizobium* D. Vibrio Difficulty: Moderate ASM Standard: 11, 24 11. Approximately what percentage of prokaryotes are thought to be pathogens? A. <1%* B. 12% C. 26% D. 48% Difficulty: Moderate ASM Standard: 23 12. Two species of bacteria live in near each other and use similar food resources. Which type of biological interaction does this describe? A. a competitive interaction* B. a cooperative interaction C. a mutualistic interaction D. a parasitic interaction Difficulty: Moderate ASM Standard: 23 13. Which of the following is a source of vitamin K for humans? A. Bacteroides thetaiotetraiotamicron digests foods, which release vitamin K. B. Escherichia coli in their digestive tract produces vitamin K.* C. S. epidermidis releases vitamin K from dead cells. D. their diet only Difficulty: Moderate ASM Standard: 23, 24 14. The human microbiome consists of which of the following? A. all microbes present on or in the body* B. pathogenic microbes only C. resident microbes only D. transient microbes only Difficulty: Moderate ASM Standard: 23 15. The most common bacterial genus found in plaque on teeth is which of the following? A. Fusobacterium* B. Haemophilus Page 3 of 17 Chapter 4: Prokaryotic Diversity C. Lactobacillus D. Streptococcus Difficulty: Moderate ASM Standard: 23 16. Who authored A Manual in Determinative Bacteriology, published in 1923? A. David Bergey* B. Robert Koch C. Barry Marshall and Robin Warren D. Louis Pasteur Difficulty: Moderate ASM Standard: N/A 17. Which of the following cannot be classified as either gram positive or gram negative on the basis of the Gram staining protocol? A. Bacillus B. Escherichia C. Mycoplasma* D. Vibrio Difficulty: Moderate ASM Standard: N/A 18. Bordetella pertussis is an example of which group of organisms? A. Cytophaga-Flavobacterium-Bacteroides B. high G+C bacteria C. Proteobacteria* D. spirochetes Difficulty: Moderate ASM Standard: N/A 19. Treponema pallidum, the causative agent of syphilis, is an example of which group of organisms? A. CFB group B. planctomycetes C. proteobacteria D. spirochetes* Difficulty: Moderate ASM Standard: N/A 20. Which of the following correctly describes the microscopic morphology of Bacteroides? A. gram-negative bacilli* Page 4 of 17 Chapter 4: Prokaryotic Diversity B. gram-negative cocci C. gram-positive bacilli D. gram-positive cocci Difficulty: Moderate ASM Standard: N/A 21. Which best describes the metabolic activities of purple sulfur bacteria? A. They are capable of nitrogen fixation, fixing nitrogen gas into nitrates and ammonia. B. They are heterotrophic and break down organic compounds to obtain energy. C. They use light energy to oxidize hydrogen sulfide, producing sulfur and sulfuric acid.* D. They use light energy to oxidize organic compounds such as sugars. Difficulty: Moderate ASM Standard: 11 22. How do Archaea differ from Bacteria? A. Archaea are found exclusively in extreme habitats. B. Archaea have ether linkages in their cell membranes.* C. Archaea have peptidoglycan cell walls. D. Archaea lack a nucleus. Difficulty: Moderate ASM Standard: 8 23. Which of the following correctly describes the metabolism of methanogens? A. They oxidize CO2. B. They oxidize H2S. C. They produce CH4.* D. They produce N2 gas. Difficulty: Moderate ASM Standard: 11 24. Which best describes Halobacterium salinarum? A. It is a type of methanogen. B. It is abundant in temperate environments. C. It is an example of the deeply branching bacteria. D. It is one of the oldest archaea.* Difficulty: Moderate ASM Standard: 5 25. Which of the following is the correct classification for the methanogens? A. Archaea* B. low G+C bacteria Page 5 of 17 Chapter 4: Prokaryotic Diversity C. Proteobacteria D. spirochetes Difficulty: Moderate ASM Standard: 11 26. Which best describes Crenarchaeota? A. aquatic archaea abundant in oceans* B. aquatic bacteria abundant in oceans C. archaea that cause dental disease D. pathogenic bacteria that infect animals Difficulty: Moderate ASM Standard: 11 27. The LPSN refers to which of the following? A. a guide to bacterial identification B. a list of approved bacterial names* C. a taxonomic key to aid identification of bacteria D. an overview of current bacterial systematics Difficulty: Difficult ASM Standard: N/A 28. Which of the following is not a genus of Betaproteobacteria? A. Bordetella B. Chlamydia* C. Leptothrix D. Thiobacillus Difficulty: Difficult ASM Standard: N/A 29. Which of the following bacterial genera is microaerophilic? A. Bdellovibrio B. Campylobacter* C. Klebsiella D. Pseudomonas Difficulty: Difficult ASM Standard: 11, 20, 22 30. Rhodospirillum, a genus capable of fixing nitrogen, is a type of which of the following? A. green nonsulfur bacteria B. green sulfur bacteria Page 6 of 17 Chapter 4: Prokaryotic Diversity C. purple nonsulfur bacteria* D. purple sulfur bacteria Difficulty: Difficult ASM Standard: 11 31. Which genus, believed to be the deepest-branching archaeal genus, has flagella and is strictly anaerobic? A. Methanosarcina B. Pyrolobus C. Sulfolobus D. Thermoproteus* Difficulty: Difficult ASM Standard: 5, 20 32. Which best describes the class Halobacteria? A. archaeans that require highly saline environments* B. archaeans that require methane-rich environments C. bacteria that require highly arid environments D. bacteria that require highly saline environments Difficulty: Difficult ASM Standard: 20 33. Methanobrevibacter oralis is an example of which type of organism? A. a bacterium that takes advantage of the conditions caused by immunosuppression, as can occur during cancer treatment B. a pathogenic archaean C. a pathogenic bacterium D. an archaean that takes advantage of the conditions caused by periodontal disease to grow; may or may not affect disease progression* Difficulty: Difficult ASM Standard: 23 34. A toga is which of the following? A. a structure produced by the fungus Tolypocladium inflatum that has medicinal uses B. an outer membrane found in a taxon within the deeply branching bacteria* C. an outer peptidoglycan layer found in a taxon within the proteobacteria D. an unusual cell wall found in some archaeans Difficulty: Difficult ASM Standard: 8 True/False Page 7 of 17 Chapter 4: Prokaryotic Diversity 35. The bacterial species found associated with the human body are very similar from one individual to another. Answer: False Difficulty: Easy ASM Standard: 21, 23 36. The phototrophic bacteria do not form a distinct taxonomic group. Answer: True Difficulty: Easy ASM Standard: 5, 11 37. Although Archaea cannot be classified as gram positive or gram negative, all Bacteria can be classified into one of these two categories. Answer: False Difficulty: Moderate ASM Standard: 5 38. Spirochetes are generally easy to culture in the laboratory. Answer: False Difficulty: Moderate ASM Standard: 11, 36 39. The deeply branching bacteria contain species that have evolved most recently. Answer: False Difficulty: Moderate ASM Standard: 5 40. All the bacteria classified within the genus Bacillus are capable of forming endospores. Answer: True Difficulty: Moderate ASM Standard: 8 41. Mycoplasmas are bacteria that lack cell walls. Answer: True Difficulty: Moderate ASM Standard: 8 Page 8 of 17 Chapter 4: Prokaryotic Diversity 42. Phototrophic bacteria may have carotenoids, which are the red and orange pigments also used as accessory pigments by plants. Answer: True Difficulty: Difficult ASM Standard: 11 43. The class Bacilli includes both rod-shaped and spherical bacterial species. Answer: True Difficulty: Difficult ASM Standard: N/A Matching 44. Match each type of association with the best definition. A. amensalism i. neither organism affects the other B. commensalism ii. both organisms benefit C. mutualism iii. one organism benefits and the other is harmed D. neutralism iv. one organism is harmed and the other is not affected E. parasitism v. one organism benefits and the other is not affected Answers: A. iv., B. v., C. ii., D. i., E. iii. Difficulty: Moderate ASM Standard: 20, 23 45. Match each type of association with the best example. A. amensalism i. A mold produces a chemical that kills bacteria without apparently benefiting. B. commensalism ii. A helminth takes up residence in a human digestive tract, consuming nutrients. C. mutualism iii. Flagellates live in the gut of termites, feeding on the wood consumed by the termite and allowing the termite access to nutrition and energy in wood that they could not otherwise digest. D. parasitism iv. Aerobic bacteria in the human colon consume oxygen, making it possible for anaerobic species to survive. Answers: A. i., B. iv., C. iii., D. ii. Difficulty: Moderate ASM Standard: 20, 23 46. Match each genus with the appropriate class of Proteobacteria. A. Alphaproteobacteria i. Myxobacterium B. Betaproteobacteria ii. Rickettsia C. Deltaproteobacteria iii. Neisseria D. Epsilonproteobacteria iv. Escherichia E. Gammaproteobacteria v. Helicobacter Page 9 of 17 Chapter 4: Prokaryotic Diversity Answers: A. ii., B. iii., C. i., D. v., E. iv. Difficulty: Moderate ASM Standard: N/A 47. Match each low G+C bacterial genus with the best description of its morphology. A. Clostridium i. chains or pairs of cocci B. Enterococcus ii. pairs of cocci, not chains C. Mycoplasma iii. gram-positive rods D. Streptococcus iv. relatively small, pleomorphic Answers: A. iii., B. ii., C. iv., D. i. Difficulty: Moderate ASM Standard: 34 48. Match each genus of Actinobacteria with its best description. A. Actinomyces i. facultative anaerobes; can live in soil and can be associated with periodontal disease B. Bifidobacterium ii. found in the human vagina and associated with vaginosis C. Corynebacterium iii. associated with legumes and fix nitrogen D. Frankia iv. can be aerobes or facultative anaerobes; form palisades E. Gardnerella v. anaerobic bacteria common in the human gut Answers: A. i., B. v., C. iv., D. iii., E. ii. Difficulty: Moderate ASM Standard: 20, 23 49. Match each group of bacteria with its best description. A. deeply branching bacteria i. large group of gram-negative bacteria that includes five diverse classes B. high G+C bacteria ii. gram-positive group that includes the Actinobacteria C. low G+C bacteria iii. gram-positive group that includes the Bacilli D. nonproteobacteria iv. many thrive at high temperatures and in harsh environments; believed to have similarities with ancient bacteria E. Proteobacteria v. gram-negative bacteria including the spirochetes, GFC group, and planctomyces Answers: A. iv., B. ii., C. iii., D. v., E. i. Difficulty: Difficult ASM Standard: 34 Fill in the Blank 50. ________ is the domain that includes the Crenarchaeota and Euryarchaeota. Page 10 of 17 Chapter 4: Prokaryotic Diversity Answer: Archaea Difficulty: Easy ASM Standard: N/A 51. The class ________ consists of high G+C bacteria. Answer: Actinobacteria Difficulty: Easy ASM Standard: N/A 52. Green and purple bacteria perform photosynthesis using green, purple, or blue pigments called ________. Answer: bacteriochlorophylls Difficulty: Moderate ASM Standard: 11 53. Purple sulfur bacteria use ________ as their source of carbon. Answer: carbon dioxide Difficulty: Moderate ASM Standard: 23, 24 54. Variability in cellular shape, as exemplified by mycoplasmas, is described by the term ________. Answer: pleomorphic Difficulty: Moderate ASM Standard: N/A 55. The ________ is a class of Proteobacteria characterized by oligotrophy and that includes chlamydias and the rickettsias. Answer: Alphaproteobacteria Difficulty: Moderate ASM Standard: N/A 56. Organisms that must live within the cells of their hosts are ________ pathogens. Answer: obligate intracellular Difficulty: Moderate ASM Standard: N/A 57. The Halobacteria are classified within the archaeal phylum ________. Answer: Euryarchaeota Page 11 of 17 Chapter 4: Prokaryotic Diversity Difficulty: Moderate ASM Standard: N/A 58. A special growth medium called ________ agar is required to culture members of the genus Neisseria. Answer: chocolate Difficulty: Moderate ASM Standard: 33, 36 59. The medically important genus Salmonella is classified within the ________ family of the Gammaproteobacteria. Answer: Enterobacteriaceae Difficulty: Difficult ASM Standard: N/A Short Answer 60. What is the term for different strains within a bacterial species, also called serotypes? Sample Answer: Different strains within a bacterial species are called serovars. Difficulty: Easy ASM Standard: N/A 61. Which genus of Gammaproteobacteria is associated with infections in patients with cystic fibrosis? Sample Answer: Pseudomonas spp. is especially important as a cause of infections associated with cystic fibrosis. Difficulty: Easy ASM Standard: 23 62. What is unusual about the morphology of myxobacteria? Sample Answer: Myxobacteria are social and capable of forming multicellular structures called fruiting bodies. Difficulty: Easy ASM Standard: N/A 63. How do cyanobacteria obtain energy? Sample Answer: Cyanobacteria are photosynthetic and can convert light energy from the sun to chemical energy they can use. Difficulty: Easy Page 12 of 17 Chapter 4: Prokaryotic Diversity ASM Standard: 11 64. What is the major way that purple nonsulfur and purple sulfur bacteria differ? Sample Answer: Purple sulfur bacteria use hydrogen sulfide for oxidation and purple nonsulfur bacteria use hydrogen for oxidation. Difficulty: Moderate ASM Standard: 11 65. Why are bacteria in the CFB group classified together even though they are phylogenetically diverse? Sample Answer: Although this group is phylogenetically diverse and not monophyletic, they share important similarities. They share some DNA sequences, are gram-negative rods, and grow anaerobically by fermentation. Difficulty: Moderate ASM Standard: N/A 66. What is the role of Bacteroides in the human gut and what are the effects of antibiotic use on them? Sample Answer: Bacteroides lives in a mutualistic relationship with humans. Humans provide nutrients and the Bacteroides help prevent the establishment of pathogenic bacteria in the human gut. When Bacteroides populations are decreased because of antibiotic use, the risk increases of harmful species becoming more abundant. Difficulty: Moderate ASM Standard: 14, 22, 23 67. Describe the classification and characteristics of Helicobacter pylori. Why is it of medical importance? Sample Answer: Helicobacter pylori is classified in the Epsilonproteobacteria and is a gramnegative, spiral-shaped rod. It is of medical importance because it is associated with gastritis, stomach ulcers, and cancer of the stomach and duodenum. Difficulty: Moderate ASM Standard: 14, 23 68. Which taxonomic groups of bacteria are considered phototrophic groups? List the groups and provide examples. Sample Answer: The phototrophic bacteria include Proteobacteria and nonproteobacteria. Phototrophic bacteria are found in the Proteobacteria and the nonproteobacteria. They include the green sulfur bacteria, the green nonsulfur bacteria, the purple sulfur bacteria, the purple nonsulfur bacteria, and the cyanobacteria. Difficulty: Moderate ASM Standard: 22 Page 13 of 17 Chapter 4: Prokaryotic Diversity 69. What is the difference between oxygenic and anoxygenic photosynthesis? Sample Answer: Oxygenic photosynthesis produces oxygen and anoxygenic photosynthesis does not. The cyanobacteria use oxygenic photosynthesis, but most prokaryotes use anoxygenic photosynthesis. Difficulty: Moderate ASM Standard: 11, 22 70. What are chlorosomes? Sample Answer: Chlorosomes are structures that resemble organelles and are used for photosynthesis in green sulfur and green nonsulfur anoxygenic phototrophic bacteria. They contain bacteriochlorophyll and are found in bacteria such as members of the genera Chlorobium and Chloroflexus. Difficulty: Moderate ASM Standard: 11 71. What are at least two differences between Archaea and Bacteria?? Sample Answer: Archaeans have ether-linked phospholipids in their cell membranes, whereas bacteria have ester-linked phospholipids. Also, most bacteria have peptidoglycan in their cell walls, whereas archaeans have other materials, such as pseudopeptidoglycan. Difficulty: Moderate ASM Standard: N/A 72. In which environment would purple sulfur bacteria more likely live: acidic, alkaline, or neutral environment? Explain why. Sample Answer: Purple sulfur bacteria oxidize hydrogen sulfide, producing sulfur and sulfuric acid as products. Unless other processes remove or neutralize the acid, their surroundings will tend to be acidic from the sulfuric acid produced. Difficulty: Difficult ASM Standard: 11, 22 73. Why are myxobacteria useful in studying intercellular communication? Sample Answer: Myxobacteria can form multicellular structures known as fruiting bodies. Understanding how the cells communicate with each other to form this complex structure requires understanding intercellular communication. Therefore, myxobacteria provide a system that may be helpful in understanding intercellular communication in other species. Difficulty: Difficult ASM Standard: 22, 25 74. Why do purple sulfur bacteria require sulfites? Sample Answer: These bacteria need sulfites as sources of electrons. Page 14 of 17 Chapter 4: Prokaryotic Diversity Difficulty: Difficult ASM Standard: 11, 22 Brief Essay Essay Question Rubric RATING Failing Criteria Answer does not for provide an evaluation argument. Answer contains inaccuracies. Writing is poor and contains numerous grammatical mistakes and misspellings. POINT VALUE 0 Below Average Answer fails to provide examples to support an argument. Writing is poor and grammatical errors are common. Answer is somewhat incoherent. Competent 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. 1 2 Advanced 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 75. The Epsilonbacteria include two genera of particular medical importance. What are these two genera and why are they important? Answer: Student answers will vary but should include components of the following. The two genera are Campylobacter and Helicobacter. C. jejuni is associated with food poisoning that causes enteritis. H. pylori can be asymptomatic but is also associated with gastritis, ulcers, and cancer of the stomach and duodenum. Difficulty: Moderate ASM Standard: 22, 23 76. each other. Is this likely to occur when two organisms exist in the same location? Explain why this particular type of interaction is difficult to identify and why some argue that it may not exist in nature. Answer: Student answers will vary but should include components of the following. Organisms that live in the same location may have indirect effects on each other that are not easily observable or measured, especially if they use the same resources and space. Even when organisms appear distinct, all the organisms in the community are likely interconnected in some direct or indirect ways. This makes it difficult to conclude that a relationship is completely neutral, with neither organism having any effect on the other. Difficulty: Moderate Page 15 of 17 Chapter 4: Prokaryotic Diversity ASM Standard: 20, 22, 23 77. Mycoplasmas are considered atypical, rather than gram positive or gram negative. Why is it not possible to use a standard Gram stain technique to classify these bacteria? What color would they appear if stained using a Gram stain technique? Answer: Student answers will vary but should include components of the following. Mycoplasmas do not have a cell wall. The Gram stain technique differentially stains bacteria on the basis of whether they have a relatively thick peptidoglycan layer that holds in the crystal violet stain (gram positive) or a thinner peptidoglycan layer with an outer membrane that lets out crystal violet when decolorized with ethanol. Mycoplasmas do not fit into either of these categories because they do not have a cell wall. If stained using a Gram stain technique, they would not have a thick peptidoglycan layer to hold in the crystal violet stain and, therefore, would show the color of the counterstain (usually pink from safranin). Difficulty: Moderate ASM Standard: 32, 34 78. Methanobrevibacter oralis is an archaean that has been identified in patients with periodontal disease. Explain how this finding does not necessarily mean causation and what would be needed to conclude that an archaean was responsible for a particular disease. Answer: Student answers will vary but should include the following. These archaeans have been found in patients with periodontal disease, but research suggests they are taking advantage of the environment produced by the disease rather than being a cause of the disease. This is an example of why it is important to remember that finding a correlation is not the same as showing causation. So far, no archaean has been found to cause disease. If the organism could be isolated from individuals with the disease, and infecting other individuals with the organism caused the disease, then that would provide more substantial evidence of a ulates. For example, it would be unethical to infect someone with a potentially dangerous pathogen. In those cases, it would be important to carefully look for the pathogen in individuals with and without the disease and to examine changes over time associated with having the microbe present, including differences in disease outcomes. Difficulty: Difficult ASM Standard: 23, 28 79. When scientists first proposed that Helicobacter pylori might be associated with stomach ulcers, other scientists were very skeptical of their conclusions. One of the researchers eventually consumed a sample and documented the effects, dramatically showing that the bacterium could cause gastrointestinal symptoms. Why do you think scientists were initially skeptical that a bacterium, rather than stress and lifestyle factors, could be responsible for gastritis, ulcers, and stomach cancer? Answer: Student answers will vary but should include components of the following. The stomach is very acidic, containing digestive enzymes as well, and it had seemed unlikely that bacteria could survive in such a hostile environment. The findings regarding H. pylori led to Page 16 of 17 Chapter 4: Prokaryotic Diversity further research demonstrating that H. pylori and other species can survive in the stomach through a variety of mechanisms. For example. H. pylori modifies its immediate surroundings using enzymes. Difficulty: Difficult ASM Standard: 14, 22, 23 d. Page 17 of 17