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MCB3023 Exam 2 Questions with Solved Correct Answers
1. How do bacteria attach to teeth?
The introductory passage describes the way in which new research showed a highly organized microbial community in dental plaque. The mouth can be an inhospitable environment with digestive enzymes in saliva and materials constantly moving through that can physically detach microbes. How does the dental plaque stay in place?: Saliva glycoproteins form a film to which bacteria can attach. Bacteria may use dextran as an adhesive. Bacteria may use capsule adhesins to adhere to glycoproteins.
2. Biofilms on teeth
Dental plaque consists of a biofilm, with bacteria carefully arranged in a community. What are the advantages of forming a biofilm?: Biofilms provide protection from immune attack.
3. What steps are involved in the formation of dental plaque? Put the steps in order from the first to
last.: 1. A thin film of glycoproteinis deposited on teeth by saliva
2. S. sobrinus uses capsule adhesins to attach toglycoproteins, and S. mutansuses dextran to attach to
enamel within crevices.
3. Bacteria ferment glucose,producing lactic acid.
4. Dental caries form
5. Periodontal disease or other infections can develop.
4. is an archaen found in dental plaque: Methanobrevibacter oralis
5. is a common bacterial species found in dental plaque.: Streptococcus sobri- nus
6. is the condition in which bacteria are found in the blood.: Bacteremia
7. is the condition in which bacteria are reproducing in the blood and spread- ing.: Septicemia
8. is needed for dental plaque formation, because it is used to produce bacte- rial capsules.: Sucrose
9. is fermented to produce the lactic acid that dissolves enamel on teeth.: Glu- cose
10. are produced as acid dissolves tooth enamel: Caries
11. Although it had been thought that dental plaque consisted primarily of streptococci, more recent
research showed that a variety of microbes are present. According to the chapter, what approaches were used to identify these additional microbes and to determine their three-dimensional structure in the biofilm?: phylogenetic probes/fluorescent in situ hybridization
12. Correctly identify the basic series of events that occurs in microbial patho- genesis.: 1)Exposure
2)invasion
3) Multiplication
is composed of polysaccharides that are similar to those found in the host; thus, the immune system does not recognize it as foreign.
20. Which of the following microorganisms actually grows inside the macrophage?:
Tuberculosis bacterium
21. How does the protozoan Trypanosoma evade detection by the immune system?: It can
change the surface antigens frequently, preventing the immune system from tracking it.
22. What are leukocidins?: Molecules that are capable of destroying phagocytes
23. Measles viruses are capable of inactivating host defenses by: suppressing the immune system
24. Meningitis and gonorrhea are caused by: Neisseria species.
25. How do superantigens enable pathogens to hide from the immune system if they actually
stimulate the immune system?: They cause the immune system to produce an exaggerated response, distracting it from the actual pathogen.
26. How can capsules enable bacteria to evade the immune system?: Capsules block the complement
biding sites on the surface of the pathogen.
27. Label the steps involved in tissue invasion.: Step 1 - hyaluronidase producer attaches to epithelia
Step 2 - production of hyaluronidase Step 3 - pathogen invades the deeper tissue
28. Which of the following features of Salmonella prevent it from being phago- cytosed?: Flagella
29. Where do Salmonella pathogens grow and replicate in the infected host?-
: Inside phagocytes
30. Where is the site of Shigella attachment in the host?: M cells
31. How do Shigella cells move between host cells?: They can polymerize actin molecules from the
epithelial cells into tail-like structures that propel them from one cell to another.
32. What is the etiologic agent of typhoid?: Salmonella
33. Identify the steps involved in diphtheria toxin activity.: 1. Diphtheria toxin
2. Receptor binds AB toxin and internalised it to cytoplasm
3. Toxin cleaved to yield part A
4. Toxin catalyses addition of ADP to EF
5. EF2- ADP blocks elongation step of translation.
34. An exotoxin that has the ability to kill or damage host cells is referred to as a(n): cytotoxin.
35. Which domain of the A-B toxin binds to cell surface receptors on the host cell?: B domain
36. How are superantigens different from other types of exotoxins?: Superanti- gens cause an
overstimulation of the host immune system.
37. A person who attended a picnic early in the day develops a very high fever and is unresponsive
by the evening. This person most likely has been exposed to a(n): superantigen.
38. A patient who has been hospitalized with uncontrolled muscle spasms has probably been infected
with bacteria that secrete a(n): neurotoxin.
40. When would endotoxins be released from a bacterial cell?: When the cell dies
41. Which of the following would be the first sign of an infection that resulted in the release of
endotoxin?: Fever
42. Why is a release of endotoxin into the bloodstream potentially deadly?: It can lower blood
pressure and cause the patient to go into shock.
43. H2S that these newly described organisms use is at the highest concen- tration in anoxic marine
habitats because produce it as an end product of anaerobic respiration, oxidizing H2 or small organic compounds with sulfate as the terminal electron acceptor.: Sulphate-reducing bacteria
44. The general term for organisms that have to use preformed organic mol- ecules is ,
whereas the general term for those that can use CO2 to synthesize organic molecules are .: heterotrophs/autotrophs
45. Rates of NH3 oxidation in nature are probably controlled by archaeal
.: nitrifiers
46. The microbes that decompose permafrost carbon to release CH4 and CO2 are most specifically
examples of .: chemoorganotrophs
47. New organic compounds are produced from inorganic substrates by
(such as plants) and .: photolithotrophs/chemolithotrophs
48. Oxic environment: Nitrification. Sulfide
oxidation.
49. Anoxic environment: Methanogenesis. Iron
reduction. Sulfate reduction.
50. The introductory passage describes the way that microbes can produce CH4 and CO2 in melting
permafrost, especially in saturated, anoxic depres- sions. Although other types may also be present, what microbes are most likely present to make these products in these conditions?: Methanogens are probably present as they produce CH4 and CO2 in anoxic environments.
51. The aerobic process that uses ammonium (NH4+) as an energy source is referred to as:
nitrification
52. A process that results in anaerobic ammonia (NH3) oxidation, uses nitrite (NO2-) as the electron
acceptor, and produces N2 as the product is the reaction.: anammox
53. The use of nitrate (NO3-) as an electron acceptor with formation of multiple gaseous end
products (N2, N2O, or NO) is: denitrification
54. An assimilatory process in which N2 is converted to ammonia (NH3) for incorporation into
organic nitrogen-containing molecules is: nitrogen fixation.
55. Many organisms release ammonium (NH4+) from degradation of nitro- gen-containing organic
materials. This process is referred to as: ammonifica- tion.
response: Type I hypersensitivity
61. is also known as delayed-type hypersensitivity and occurs when Th1 cells activate
macrophages.: Type IV hypersensitivity
62. Do you think that the consumption of raw milk could also reduce the risk of autoimmune
diseases such as type I diabetes (T1D) and systemic lupus erythematosus (SLE)?: Probably not, because the introductory passage describes effects on type 1 hypersensitivities. T1D and SLE are not caused by type 1 hypersensitivities.
63. Innate immune response: Pathogen associated molecular patterns(PAMPs) Pattern recognition
receptors(PRRs)
64. Adaptive immune response: Major Hiscompatibility Proteins. T-cell Receptors.
(TCRs) Innumoglobulins.
65. undergo degranulation to release their contents, which cause inflamma- tion.: Mast cells
66. develop from certain B cells (not all) and secrete antibodies.: Plasma cells
67. bind antigen, but only when it is presented by a structure on another cell: T cell receptors
68. presents peptides to T cells and is only found on specific types of nucle- ated cells.: Class II
MHC
69. include B cells, dendritic cells, and macrophages.: APCs
70. are released by plasma B cells and interact with antigens.: Igs
71. presents peptides to T cells and is found on the membranes of all nucleated cells.: Class I MHC
72. Individuals with two different alleles at an MHC protein locus express both genes and, therefore,
have both proteins on their cell membranes. This is an example of: codominance
73. Class I MHC proteins are encoded by three loci that are related (they are a result of gene
duplication). The existence of these three related loci-encoding Class I MHC proteins is an example of: Polygeny
74. Having multiple alleles expressed within a population, such as with MHC proteins, is an example
Step - 3 Plasma cell secreate antibodies that recognize virus
86. Part A - Correctly sort the steps involved in cell-mediated immunity Part complete
Put the steps involved in cell-mediated immunity in order.: 1.) In the lymph nodes, cytotoxic T cells encounter dendritic cells displaying epitope on MHC-I. The Tc cell is activated
2.) The active cytotoxic T cell (TCL) leaves the lymph node "looking" for infected host cells displaying the
same epitope on their MHC-I. The CTL uses its surface receptors to recognize the infected cell
3.) The CTL secretes specialized molecules to penetrate the infected host cell causing
programmed death
87. Antigen processing and presentation: is a way for a cell to give information about its activities.
88. Why would a body cell that is not a phagocyte need to present antigens?-
: Non-phagocytic body cells can become infected with a virus.
89. How do phagocytes communicate to other cells what they have captured?-
: They present antigens from engulfed foreign cells.
90. Where are MHC molecules located on a cell?: On the surface of the cell
91. What is a feature of the small fragments presented by MHC-I proteins?: -
They are small peptides, roughly 8-10 amino acids long.
92. Which organelle assists directly with the presentation of MHC-I antigens?-
: The endoplasmic reticulum
93. When does MHC-II loading occur?: During the fusion of vesicles containing MHC-II proteins with
vesicles containing digested pathogens
94. Which of the cells listed below can present antigens on Class II MHC proteins?:
Macrophages
95. What is apoptosis?: The process of programmed cell death.
96. What is the function of the CD8 receptor?: Bind to MHC molecules
97. What is the fate of activated cytotoxic T-cells?: They proliferate into a clone of cells specific to the
same antigen; some of these cells then differentiate into long-lived memory T-cells, while others mature to attack infected cells.
98. Which molecule triggers apoptosis?: Granzyme
99. Which event happens first during cytotoxic T-cell activation?: CD8 binds to MHC molecules of
infected cells
100. The introductory passage explains that the amyloid-²pý rotein may function in the innate immune
response. Which of the following best describes another example of innate immunity?: Nonspecific or innate immunity occurs when phago- cytes respond to common features against a variety of pathogens.
109. leukocytes mature in the thymus and are involved in cell-mediated immu- nity.: T cell
110. differentiated lymphocytes, matured from one of the major types, produce immunoglobulins.:
Plasma cell
111. lymphocytes function primarily in innate immunity against viruses and cancer cells.: Natural-
killer cell
112. The A²pý rotein appears to function in the innate immune response. An important component
of the innate immune response is inflammation. Which of the following is an important characteristic of inflammation? Instructions: Choose all possible answers.: The major characteristics of inflammation are erythema, edema, heat, and pain. Chemokines and cytokines play a role in triggering inflammation.
113. A response that is uniquely directed against pathogenic Bordetella per- tussis would involve
what component?: Antibodies
114. First line defenses have what aspect in common with each other?: They are physical barriers
against invading pathogens.
115. Both the innate and adaptive defenses of the immune system work to prevent: the
penetration and colonization by pathogens, and the diseases they cause.
116. If a new bacterial pathogen entered a human body through an accidental needle stick, the first
cell that would try to kill the pathogen would likely be: a phagocyte.
117. Mucous membranes are a part of: innate defense.
118. According to the animation, B cells interact directly with: helper T cells.
119. Which of the following defense systems would be involved in fighting a viral pathogen?: T
lymphocytes
130. Phagocytosis is defined as: the ingestion of solid material by a eukaryotic cell.
131. How is phagocytosis in the immune system different from protozoan phagocytosis?:
Protozoan phagocytosis is used for feeding; phagocytosis by im- mune cells is used to fight infection.
132. An inflammatory response would result from which of the following?: Jel- lyfish sting
133. If a person turns their ankle, how would one determine if damage to the tissue in the ankle has
occurred?: The ankle is red, swollen, and warm to the touch
134. What is the function of inflammation in response to a burn from a hot iron?: To repair the
damaged tissue
135. What direct effect do histamines and leukotrienes have on capillaries?: -
They allow capillary walls to open and become leaky.
136. Diapedesis is: the migration of phagocytes through blood vessels to the site of tissue damage.
137. Why is vasodilation important to tissue repair?: It allows for an increased delivery of oxygen,
nutrients, and phagocytes to the site of damage.
138. Pus is comprised of: dead phagocytes.
139. Which of the following can release histamines?: Cells from damaged tis- sues and the
complement pathway
140. Each of the different activation pathways for complement has advantages and disadvantages
compared to the other two pathways. Which of the follow- ing correctly lists an advantage and a disadvantage of classical activation in response to a new microbial intruder?: Advantage: very
specific. Disadvantage: slow to induce complement.
141. The classical pathway of complement activation begins with binding of: an antibody
142. A microbe has the ability to inhibit complement activation of inflamma- tion, but it cannot
inhibit complement activation of opsonization and cytol- ysis. Therefore, the microbe has produced inhibitors of which complement protein(s)?: C3a and C5a
143. Blood serum contains cells and clotting proteins.: False
144. The and domains of the class II MHC protein interact to form a
peptide-binding site.: ±1 / ²
145. Which of the following is/are MHC class I genes?: HLA-A, HLA-B, and HLA-C
146. Antihistamines are used to treat some allergic symptoms because they neutralize the histamine
mediators that cause rapid dilation of blood vessels and contraction of smooth muscles that initiate the symptoms of systemic anaphylaxis.: True
147. Immunity results from the actions of cells that circulate throughout the body, primarily
through the blood and lymph.: True
148. Individuals with severe combined immunodeficiency syndrome (SCID) have a genetic defect
that prevents proper formation and expression of im- munoglobins and T cells and therefore do not have adaptive immunity.: True
149. Th17 cells are important in the first stages of the adaptive immune re- sponse.: True
150. Assuming that each heavy and light chain has an equal chance to be expressed in each cell,
approximately how many possible antibodies can be expressed?: 3,360,
