Biology 2261Name
Spring 1999 First Examination
Be sure to put yourname on the mark-sense sheet.
Put your name on the exam booklet. Both the exam booklet and the mark-sense sheet must be turned in at the end of the period.
You may write in the exam booklet, but only the mark-sense sheet will be graded. No other paper, scratch paper, etc., may be used.
Students must turn in the exam before leaving the room for any reason. A student may not continue working on the exam after having left the room.
Multiple Choice. 50 questions, 2 pt each.
1.Which of the following statements best summarizes Koch’s postulates?
(a)Bacteria and other simple microorganisms can spontaneously form from simple chemical interactions in nonliving organic matter.
(b)To demonstrate that a disease condition is caused by an infectious microorganism, one must identify the microorganism in a statistically significant (5% confidence level) proportion of the diseased population.
(c)Bacteria and other simple microorganisms do not form from spontaneous generation in nonliving matter, but from reproduction of living microbial cells.
(d)To demonstrate that a disease condition is caused by an infectious microorganism, one must isolate the microorganism from an infected individual, infect a healthy experimental animal with a pure culture of the microorganism, demonstrate the development of the disease symptoms in the experimental animal, and re-isolate the same microorganism from the experimental animal.
(e)To prevent the spread of infectious disease, infected individuals must be isolated from healthy individuals, and contaminated clothing and other objects must be sterilized.
2.In bacteria, antibiotic resistance and ability to conjugate are usually encoded by
(a)chromosomal DNA(d)viral DNA
(b)plasmid DNA(e)nuclear DNA
(c)ribosomal RNA
3.A disease that is normally present in a certain percentage of a population is a(n)
(a)communicable disease(d)epidemic disease
(b)contagious disease(e)endemic disease
(c)noncommunicable disease
4.Certain strains of the bacterium Corynebacterium diphtheriae contain an extra gene that codes for an exotoxin. These strains can cause a severe infection called diphtheria. Other strains that do not have the gene for the exotoxin produce no infection in humans. Which of the following statements best describes the relationship between strains that produce the exotoxin and those that do not?
(a)Strains that produce the toxin are acute, and strains that do not produce the toxin are chronic.
(b)Strains that produce the toxin are primary, and strains that do not produce the toxin are secondary.
(c)Strains that produce the toxin are localized, and strains that do not produce the toxin are systemic.
(d)Strains that produce the toxin are virulent, and strains that do not produce the toxin are nonvirulent.
(e)Strains that produce the toxin are epidemic, and strains that do not produce the toxin are endemic.
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The following information pertains to questions 5 - 8.
In each of the following questions, a description of a microorganism is given. Based on the description, determine which of the following choices best describes the microorganism.
(a)The microorganism is prokaryotic.
(b)The microorganism is eukaryotic.
(c)The microorganism is a virus.
5.The organism responsible for anthrax consists of rod-shaped cells. Each cell is surrounded by a thick layer of highly cross-linked peptidoglycan. The DNA of the cell is a circular DNA molecule found in the nucleoid region of the cell’s cytoplasm. Cellular respiration is carried out by proteins located in the cell’s plasma membrane.
6.Rickettsia rickettsii is responsible for the condition known as Rocky Mountain Spotted Fever. Although this organism grows only within an infected host, it has its own DNA and RNA to direct the synthesis of its protein and to control its cell division. Its DNA is found in the nucleoid region of its cytoplasm, but there is no nuclear membrane surrounding the DNA.
7.Euglena gracilis is a member of the kingdom Protista. It is a free-living organism often found on the surfaces of ponds. The most notable feature of this single-celled organism is its chloroplast, a membrane-enclosed organelle that absorbs light energy and uses it to manufacture carbohydrates. The organism is motile by means of a flagellum that moves back and forth in a whip-like motion to propel the organism forward.
8.When the pathogen responsible for dengue fever penetrates its host cells, its RNA is released from the protein shell. Within the host cell, the dengue RNA directs the synthesis of protein and RNA molecules that are assembled into many more infectious dengue particles.
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The following information pertains to questions 9 - 11. Thioglycolate broth is a differential medium used to determine the oxygen requirements of bacteria. When a test tube of thioglycolate broth is prepared, an oxygen gradient is established. This means that there is a high concentration of oxygen at the surface of the broth, less oxygen in the middle of the tube, and no oxygen at the bottom of the tube. The following choices are used for questions 9 - 11.
(a)strict aerobe(d)aerotolerant anaerobe
(b)strict anaerobe(e)microaerophile
(c)facultative anaerobe
9.If cells of a bacterial species grow equally well throughout a thioglycolate broth tube, to which group does the species belong?
10.If cells of a bacterial species grow in one narrow band somewhere in the middle of the tube between the surface and the bottom of the tube, to which group does the species belong? (Note: the bacteria do not grow on the surface nor on the bottom, but in a narrow band in the middle.)
11.If cells of a bacterial species grow throughout a thioglycolate broth tube, but they grow better at the top of the tube than at the bottom of the tube, to which group does the species belong?
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The following information pertains to questions 12 and 13.
The graph below shows the growth rate of a certain bacterial speciesat different temperatures. In this graph, a larger growth rate value indicates that the bacteria grew faster (divided more frequently) at that temperature.
12.Based on the data, which of the following terms best describes the organism?
(a)Extreme thermophile
(b)Moderate thermophile
(c)Mesophile
(d)Psychrophile
(e)Halophile
13.Based on the data, which of the following conclusions can you reach?
(a)The cells of this bacterial species cannot survive at temperatures above 75C.
(b)The cells of this bacterial species cannot survive at temperatures below 45C.
(c)Both (a) and (b) are valid conclusions based on the data.
(d)Neither (a) nor (b) are valid conclusions based on the data.
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14.Which of the following regions of the human body is free of normal flora under normal conditions of health?
(a)upper respiratory tract(d)more than one of the above
(b)skin surfaces(e)none of the above
(c)large intestine
15.Which of the following best describes the structure of peptidoglycan?
(a)a polymer of glycerol or ribitol linked by phosphate groups
(b)a polymer of alternating glucosamine and ethanolamine units linked by ester bonds
(c)a polymer of -hydroxybutyrate units linked by pentapeptide bridges
(d)a polymer of alternating N-acetylglucosamine and N-acetylmuramic acid units linked by glycosidic bonds
(e)a polymer of O chain polysaccharide and core polysaccharide attached to a Lipid A molecule
16.How does the peptidoglycan layer of archaeobacteria differ from that of the gram-negative bacteria?
(a)It is much thicker.(d)More than one of the above
(b)It is much more highly crosslinked.(e)None of the above.
(c)It has strands of teichoic acid inserted into it.
17.Adjacent chains of peptidoglycan may be covalently crosslinked by
(a)short chains of lipopolysaccharide molecules.
(b)short chains of amino acids.
(c)metachromatic granules
(d)More than one of the above.
(e)None of the above.
18.Phenylketonuria is an inborn error of metabolism in humans that results from the genetic inability to make an enzyme necessary for the break down of the amino acid phenylalanine. Consider the following statements about phenylketonuria.
I.Phenylketonuria is a disease.
II.Phenylketonuria is a chronic infection.
III.Phenylketonuria is a primary infection.
IV.Phenylketonuria is an noncommunicable infection.
V.Phenylketonuria is an endemic infection.
(a)All statements (I, II, III, IV, and V) are true.
(b)Only statements I and II are true.
(c)Only statements I and III are true.
(d)Only statements I, II, and III are true.
(e)Only statement I is true.
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The following choices are used for questions 19 - 20.
(a)reservoir of infection(d)animal vector
(b)fomite(e)aerosol
(c)human carrier
19.Which is the best (most specific) term to describe an insect which carries pathogenic microbes on its feet from garbage to human food sources?
20.Which is the best (most specific) term to describe an inanimate object that is contaminated with pathogenic microbes?
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21.The period of time between the colonization of a pathogen into its host and the appearance of the initial symptoms of infection is called the
(a)prodromal period(d)incubation period
(b)convalescent period(e)decline period
(c)invasive period
22.Which of the following statements is true?
(a)Endotoxins produce varied effects such as neurotoxic or protein inhibition effects, but exotoxins produced generalized irritation and inflammation of epithelial surfaces.
(b)Endotoxins are found attached to the cell wall of certain bacteria, but exotoxins are secreted toxins that may exhibit their effect independently of the presence of the bacteria.
(c)Exotoxins include the neurotoxins of botulism and tetanus, while endotoxins include the enterotoxin of Staphylococcus aureus.
(d)More than one of the above statements are true.
(e)None of the above are true.
23.Metachromatic granules are composed of
(a)sulfur(d)polysaccharide
(b)lipid(e)protein
(c)phosphate
24.The O side chain antigen is a component of
(a)the outer membrane of the gram-negative cell wall.
(b)the hook-and-rotor assembly of a bacterial flagellum.
(c)the spore coat of a bacterial endospore.
(d)the inner leaflet of a bacterial plasma membrane.
(e)the photosynthetic electron transport chain of a chlorplast.
25.In bacteria that possess flagella, a change of direction in movement is accomplished when
(a)ions are pumped through porin protein channels, causing the electrical polarity of the cell surface to change from positive to negative.
(b)ions are pumped through porin protein channels, causing the electrical polarity of the cell surface to change from negative to positive.
(c)electrons are transported through a series of membrane proteins, causing an increase in the cytoplasmic concentration of ATP.
(d)the rudder proteins of the flagellar basal body undergo a conformational change, altering the angle between the flagellar filament and the cell surface.
(e)the direction of the flagella’s spin reverses, causing the cell to tumble and change its orientation in a random fashion.
26.This person, in the 1800s, suggested that hand-washing by physicians could reduce the transmission of infection to women during labor and delivery.
(a)van Leeuwenhoek(d)Semmelweis
(b)Koch(e)Snow
(c)Pasteur
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The following information pertains to questions 27 - 29.
A healthy child was exposed to a virulent strain of the bacterium Hemophilus influenzae.
27.Within several days, she developed severe pharyngitis due to the Hemophilus infection. Which of the following statements best describes the Hemophilus infection at this point?
(a)It is a primary, systemic infection.(d)It is a secondary, localized infection.
(b)It is a primary, localized infection.(e)It is an acute, subclinical infection.
(c)It is a secondary, systemic infection.
28.After two more days, the infection spread to her bloodstream. She developed bacterial septicemia and meningitis. Which of the following statements best describes the Hemophilus infection at this point?
(a)It is a primary, systemic infection.(d)It is a secondary, localized infection.
(b)It is a primary, localized infection.(e)It is an acute, subclinical infection.
(c)It is a secondary, systemic infection.
29.While in the hospital, the sick child was exposed to the human respiratory syncytial virus (RSV). The virus infected her lungs causing viral pneumonia. There was no evidence that the RSV virus had spread beyond her lungs. Which of the following statements best describes the RSV infection?
(a)It is a primary, systemic infection.(d)It is a secondary, localized infection.
(b)It is a primary, localized infection.(e)It is an acute, subclinical infection.
(c)It is a secondary, systemic infection.
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30.Look at the names of each of the bacteria listed below.
I.Bacillus megaterium
II.Group A streptococcus
III.tuberculosis
IV.Diphtheria bacillus
V.Staphylococcus epidermidis
Which of the names is (are) written according to the formal rules of systematic binomial nomenclature?
(a)II and IV only(d)I and V only
(b)I, III, and V only(e)I, IV, and V only
(c)I, III, IV, and V only
31.A system of classification in which organisms are grouped together to reflect genetic similarity and evolutionary relatedness is a
(a)binomial system(d)parthogenic system
(b)phenetic system(e)phylogenetic system
(c)nomenclature system
32.A sample of mucous from the trachea of a healthy volunteer was collected by having the volunteer cough up the mucous and spit it into a sterile cup. A colony count revealed the presence of 6500 viable bacterial cells per ml of mucous. A second sample was taken from the same volunteer on the same day, but it was taken by withdrawing it directly from the trachea using a sterile syringe. In the second sample, a colony count revealed that no bacteria were present. Which of the following statements gives the most likely explanation of these results?
(a)A strong immune response destroyed the normal flora of the lower respiratory tract between the time that the first sample was taken and the time that the second sample was taken.
(b)The lower respiratory tract is free of normal flora. Bacteria from the oral cavity were responsible for bacterial contamination in the first sample.
(c)The bacteria in the first sample developed from the process of spontaneous generation.
(d)All of the normal flora of the lower respiratory tract were expelled when the first sample was taken.
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The following choices are used for questions 33 - 36.
(a)Protein A(d)collagenase
(b)Lipid A(e)flagellin
(c)Protein M
33.Which substance contributes to the adhesion of pathogenic Streptococcus pyogenes cells to host tissue?
34.Which substance acts as a bacterial endotoxin?
35.Which substance contributes to motility?
36.Which substance is a component of the gram-negative bacterial cell wall structure?
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The following choices are used for questions 37 - 38.
(a)coagulase(d)leukocidin
(b)streptokinase(e)hemolysin
(c)hyaluronidase
37.This enzyme triggers clot formation.
38.This enzyme destroys a key carbohydrate component between host cells which loosens the connection between the cells in host tissue.
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39.The staphylococcal enterotoxin
(a)is composed solely of Lipid A.
(b)is among the most heat-resistant of exotoxins.
(c)can be destroyed by placing food in a refrigerator.
(d)produces a condition of rigid paralysis.
(e)is more lethal than the botulism toxin.
40.Proteus vulgaris, a bacterium, is part of the normal colon flora in most people. There is no direct benefit to the person in having this organism in the colon, and it is not pathogenic. Which term best describes the relationship between Proteus vulgaris and the humans it inhabits?
(a)Mutualism(d)Syncytialism
(b)Parasitism(e)Plagiarism
(c)Commensalism
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The following choices are used for questions 41 - 42.
(a)bacillus(d)spirillum
(b)coccus(e)spirochaete
(c)vibrio
41.This term designates flexible, helical-shaped bacterial cells.
42.This term designates comma-shaped bacteria.
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The following choices are used for questions 43 - 44.
(a)streptococcus(d)diplococcus
(b)staphylococcus(e)tetrad
(c)sarcina
43.This term designates spherical bacterial cells arranged in clusters.
44.This term designates spherical bacterial cells arranged in cubical packets of eight cells.
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The following choices are used for questions 45 - 47.
(a)gram-positive bacteria(d)archaeobacteria
(b)gram-negative bacteria(e)mycoplasmas
(c)acid-fast bacteria
45.The cells of this group are difficult to stain due to the high concentration of mycolic acid in their cell walls.
46.The enzyme lysozyme hydrolyzes the bonds between the monomer units of peptidoglycan. Based on this information, which group do you predict should be the most sensitive to the antimicrobial action of lysozyme?
47.Teichoic acid is a cell wall polymer associated with this group.
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48.Which of the following best describes the function of bacterial spores?
(a)They provide a mechanism for bacterial reproduction.
(b)They mediate the process of spontaneous generation in bacteria.
(c)They induce positive and negative chemotactic responses in bacteria.
(d)They help ensure the survival of the species during conditions of nutrient depletion and waste buildup.
(e)More than one of the above.
49.How do the S strain and R strain of Streptococcus pneumoniae differ from each other?
(a)The strains belong to different genera.
(b)The strains belong to different species.
(c)Cells of the S strain are encapsulated and virulent, while cells of the R strain are not encapsulated and not virulent.
(d)Cells of the R strain are encapsulated and virulent, while cells of the S strain are not encapsulated and not virulent.
(e)More than one of the above choices is true.
50.Which of the following statements is FALSE?
(a)Gram-negative cells have an outer membrane containing lipopolysaccharide, while gram-positive cells do not.
(b)Gram-positive cells retain the crystal violet dye and stain purple or violet during gram staining, while gram-negative cells do not.
(c)Gram-positive cells can have teichoic acid in their cell walls, while gram-negative cells do not.
(d)Gram-negative cells have a thick layer of peptidoglycan in their cell wall structure, while gram-positive cells do not.
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