Microbiology 208 Final Exam: Multiple Choice Questions and Answers, Exams of Microbiology

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In 1994 a civil war in Rwanda displaced 3.9 million people, many of whom fled to refugee camps in Goma, Zaire. Conditions in refugee camps led to rapid spread of infectious diseases including a disease causing severe, watery diarrhea. Microbes isolated from the stool samples of these patients with Gram stained showed a curved, Gram negative microorganism to be present. This microbe was identified as Vibrio cholerae. Based on this information and what you know from chapter 3, what can you conclude? - Correct Answers V. cholerae has a two plasma membranes that surround a peirplasmic space and a peptidoglycan cell wall. Select all of the conclusions that can be drawn from Pasteur's experiments w the S-shaped flasks? - Correct Answers Microorganisms can be present in nonliving mater, such as air, liquids, and solids. Microbes can be blocked from accessing favorable growth conditions. Microbial life can be destroyed by heat. Bacteria without a capsule are easier for the host's immune systems to kill than bacteria with a capsule. Why? - Correct Answers The capsule prevents phagocytosis and increases bacterial virulence. A virus's ability to infect an host cell depends primarily upon the - Correct Answers presence of receptor sites on the host cell membrane. Why do bacteria grow at less than their optimum doubling time during the lag phase? - Correct Answers During lag phase, bacteria are synthesizing molecules to prepare for rapid cell growth. Which of the following pairs of microbe classification terms and optimal growth temperatures is mismatched? - Correct Answers thermophile, 25°C There were five major cholera outbreaks in the 1800's that occurred all over the world and killed nearly 40 million people. During this time period,

cholera can be classified as a(n) _____ disease. - Correct Answers pandemic Which of the following violates Koch's postulates? - Correct Answers V. cholera bacteria can be isolated from both cholera patients and healthy individuals. A house fly transmits tularemia by carrying tularensis on its feet. This is an example of - Correct Answers mechanical transmission. How could disease transmission be stopped at the portal of exit? - Correct Answers covering the mouth when sneezing AND wearing a condom. Which of the following is NOT a reservoir of infection? - Correct Answers All of these answers can be a reservoir of infection. A positive antibody test for HIV infection would be a _____ of infection. - Correct Answers sign At the start of 2015, 36.5 million people were living with HIV in the world. If 2 million people contract HIV in 2015, what was the prevalence of HIV in the world at the end of 2015? (Assume the world population at the end of 2015 was 7.5 billion) - Correct Answers 38.5 million/7.5 billion A Healthcare-Association Infection is - Correct Answers acquired during the course of hospitalization. Endotoxins are - Correct Answers part of the gram-negative cell envelope. A physician transmits Influenza from one patient to another patient because of viral contamination on the stethoscope. The flu was transmitted _____ via _____. - Correct Answers indirectly, fomite The first step for directly linking a microbe to a specific disease according to Koch's postulates is to - Correct Answers obtain a sample of blood or other body fluid from a diseased animal. In which of the following patterns of disease does the patient experience no signs or symptoms? - Correct Answers incubation

Scenario 14. During a six-month period, 239 cases of pneumonia occurred in a town of 300 people as a result of Coxiella burnettii infections. Before the outbreak, 2000 sheep were kept 30 miles northwest of the town, 95% of sheep tested were positive for C. burnetii. Wind blew from the northwest, and rainfall was 0.5 cm compared with 7 to 10 cm during each of the previous three years. The method of transmission of the disease in Situation 14.1 was - Correct Answers vehicle. What is the correct definition of an endemic disease? - Correct Answers a disease that is constantly present in a population Which of the following is an example of an opportunistic infection? - Correct Answers After taking an antibiotic you develop thrush, an infection caused by overgrowth of the normal microbe C. albicans in your mouth. At the start of 2015, 36.5 million people were living with HIV in the world. If 2 million people contract HIV in 2015, what was the incidence of HIV in the world in 2015? (Assume the world population at the end of 2015 was 7. billion) - Correct Answers 2 million/7.5 billion Chlamydia is the most common reportable sexually-transmitted infection (STI) in the United States. - Correct Answers True Two different flu virus strains infected a pig at the same time, recombined into a new flu virus, and the new flu virus infects a human. What will occur after this antigenic shift now that the new flu virus is in the human population? - Correct Answers The new flu has RNA genome from both original strains. Which person would likely have the most mild disease following an Epstein- Barr infection? - Correct Answers An otherwise healthy toddler. Which list of three terms best describes innate immunity? - Correct Answers quick, nonspecific, and unchanged from birth M. tuberculosis can adhere to the lung tissue or can reside inside the cytoplasm of a human macrophage cell. Which of these forms of M. tuberculosis infection would be targeted by CD8+ cytotoxic T cells? - Correct Answers M. tuberculosis inside a macrophage

......cells express MHC class I molecules on their surface so that they can display ....... antigens that are ..... - Correct Answers All nucleated cells intracellular are infecting them Which of the following would alter a B cell's ability to bind to an antigen? - Correct Answers A DNA mutation that causes an alteration in the B cell receptor. Figure 1 shows the antibody response in a host following antigen exposure. Based on the figure, you can conclude that the antigen in the initial exposure and in the secondary exposure was _____. - Correct Answers the same antigen Streptococcal infections are extracellular. What adaptive immune cells are important in protecting against strep? - Correct Answers T-helper cells and B-Cells What type of vaccine is the live, weakened measles virus? - Correct Answers attenuated whole-cell vaccine All of the following events occur to elicit an antibody response. Put them in the order they occur from step 1 to step 5. - Correct Answers 1- the antigen-Presenting... 2- Part of the digested antigen 3- The helper T cell recognizes 4- T helper T cell produces 5- B cell is activated An example of artificial active immunity would be - Correct Answers chickenpox vaccine triggering extended immunity to chickenpox. Which of the following contribute to the specificity of adaptive immunity? - Correct Answers Each B and T cell has a unique receptor that recognizes antigen. In an experiment, an animal was injected with two different antigens. After several days, B lymphocytes were removed from the animal and the individual B cells were placed in separate small containers. Then the

original two antigens were placed in the containers with each B cell. What results would you expect to observe? - Correct Answers Some B cells produced an antibody to one of the antigens and not both of them. Some of the B cells did not produce antibodies to any of the antigens. How do helper T-cells (CD4+) and cytotoxic T-cells (CD8+) work together?

• Correct Answers Helper T-cells produce cytokines to activate cytotoxic T cells and other cells of the immune system. In vaccination, a person is exposed to material that is antigen but not pathogenic. - Correct Answers True Which of the following statements are FALSE? - Correct Answers Before surgery, the patient's skin must be disinfected. Moist heat destroys organisms by denaturing proteins - Correct Answers True ______ is very toxic but is commonly used to disinfect hospital equipment and kills microbes by inactivating their proteins. - Correct Answers Formaldehyde ______ is very toxic but is commonly used to disinfect hospital equipment and kills microbes by inactivating their proteins. - Correct Answers Formaldehyde A sample of E. coli has been subjected to heat for 17 minutes and all of the cells in the sample are destroyed. Which of the following terms best describes this event? - Correct Answers thermal death time Which of the graphs in the figure best depict the effect of placing a culture of bacteria in an autoclave at time x? - Correct Answers b Which of the following regarding antimicrobial control agents is FALSE? - Correct Answers Alcohol is most effective at 100% concentration. Why does milk eventually spoil despite being pasteurized? - Correct Answers Pasteurization reduces the microbe count in the milk and doesn't achieve sterilization.

______ is the preservation of beef jerky from microbial growth by removal of water and is a ____ form of microbial control. - Correct Answers Desiccation, bacteriostatic In order to prepare instruments for surgery, it is necessary to sterilize them which is - Correct Answers removal of all microbial life. You use a germicide to destroy various types of microbes on surfaces in your house. You have to leave the germicide on the kitchen counter for 1 minute to kill all of the enveloped viruses contaminating it from the chicken you prepared for dinner. If you want to use the same chemical in the bathroom to kill the sporulating Clostridium bacteria in the toilet, you should ____ the incubation time with the same chemical. - Correct Answers increase Cattle feed mixed with 106 coli was subject to heating at 55°C, 60°C, and 65°C. The number of E. coli remaining in the feed after heating for 120 seconds is shown below. Estimate the thermal death time for the E. coli in cattle feed at 65°C. - Correct Answers >120 seconds Which of the following is TRUE about clonal selection? - Correct Answers Each lymphocyte has specificity to only one antigen and will react to only that antigen. B cells are activated by a(n) _____ to become plasma cells. - Correct Answers antigen B cells, macrophages, and dendritic cells differ from other human cells in that they express ______ on their surface. - Correct Answers MHC-II receptors A phagocyte with a DNA mutation that prevented formation of a functional Toll-like receptor would have difficulty with which specific step of phagocytosis? - Correct Answers adhering to the microbe What does an antigen bound to MHC I on the surface of a cell indicate about that cell? - Correct Answers The cell is infected with an endogenous antigen.

In general, what sorts of pathogens may be able to more successfully attack a patient with an inability to synthesize B lymphocytes? - Correct Answers Extracellular antigens Which of the following is NOT a mechanism of defense against microbial infection in the skin? - Correct Answers Hair follicles prevent entry of microbes into host tissues. What type of immunity results from vaccination? - Correct Answers artificially acquired immunity Neutrophils, dendrites, and macrophages are all innate immune cells that are capable of _____. - Correct Answers phagocytosis. Which of the following is the best definition of epitope? - Correct Answers specific regions on antigens that interact with antibodies Which of the cells listed below can present extracellular antigens on Class II MHC proteins? - Correct Answers B cells or macrophages Newborn immunity resulting from the transfer of antibodies across the placenta is - Correct Answers naturally acquired, passive immunity. Which of the following contribute to the specificity of adaptive immunity? - Correct Answers Each B and T cell has a unique receptor that recognizes antigen. The function of the "ciliary escalator" is to - Correct Answers trap microorganisms in mucus and move them away from the lower respiratory tract. A child falls and suffers a deep cut on her leg. The cut went through her skin and she is bleeding. Which of the following defense mechanisms will try to eliminating contaminating microbes immediately? - Correct Answers phagocytosis and the inflammatory response Phagocytes utilize all of the following to help locate and contain microorganisms EXCEPT - Correct Answers lysozyme

All of the following occur during inflammation. What step occurs first? - Correct Answers Chemical signals are released by pathogens and injured tissues. Which of the following statements regarding antibody function is FALSE? - Correct Answers They can penetrate host cells to bind endogenous antigens How does a phagocyte "know" it is in contact with a pathogen instead of another body cell? - Correct Answers Phagocytes recognize Pathogen- Associated Molecular Patterns (PAMPs) on the surface of pathogens. What process generates many B cells that are activated against specific antigens? - Correct Answers Clonal selection Innate immunity includes all of the following EXCEPT - Correct Answers production of antibody. Innate immunity includes all of the following EXCEPT - Correct Answers production of antibody. Select all of the following that would either enhance or reduce a phagocyte's ability to bind to a microbe. - Correct Answers Initiation of the complement cascade results in the microbe being coated in the complement protein C3b. A DNA mutation that causes alteration in the phagocyte's Toll-Like Receptors. The microbe acquired the ability to make a capsule. What makes IgM particularly effective at controlling the spread of an infection in a host? Select all that apply. - Correct Answers It is the first type of antibody produced by the adaptive immune system. Its multiple antigen binding sites enable it to agglutinate many microbes at once.

How is a T-cell receptor different from a B-cell receptor? - Correct Answers T-cell receptors must have antigen broken down inside a cell and presented to them by a Major Histocompatibility Complex (MHC) molecule. Your neighbor's child has been diagnosed with a disease that causes the child to make no antibodies. Which of the following functions is this child still able to perform at normal levels? - Correct Answers Stop viruses from binding to cells. Put these steps in order:1. B cell receptor on surface of B cells binds antigen.2. Antigen breakdown products bind major histocompatibility complex protein and are "displayed" on B cell surface.3. Antigen-antibody complex is internalized and processed.4. B cell is activated to divide and differentiate into plasma cells and memory cells. - Correct Answers 1, 3, 2, 4 What is required for a B cell to differentiate into a plasma cell? Select all that apply. - Correct Answers Cytokines released by a CD4+ T cell after the B cell displays an antigen. The B cell receptor binds to antigen. The B cell receptor binds to antigen Select all of the TRUE statements about antigen presentation of intracellular and extracellular antigens. - Correct Answers Intracellular antigens are presented on MHC I proteins but extracellular antigens are presented on MHC II proteins. Intracellular antigens are inside a host cell but extracellular antigens are outside and must be brought into the host cell. Cytotoxic T cells recognize intracellular antigens but helper T cells recognize extracellular antigens. an interaction between two immune cells and an antigen is shown in the figure. MCHO and T cell receptor are sticking out from the surface of cell 1 and 2 respectively and interacting with each other as shown. Identify the immune cells - Correct Answers cell 1: nucleated cell, cell2: CD8 T cell

A patient has a lesion on their thigh that is infected with MRSA. MRSA bacteria are coated in a capsule and are able to survive in the cytoplasm of the phagocyte to prevent their destruction by phagocytosis. Which steps in phagocytosis are MRSA able to inhibit? - Correct Answers Formation of the phagolysosome (not sure) maybe adherence and formation of the phagolysosome which non-specific innate defense mechanism is mismatched with its associated body structure or body fluid? - Correct Answers Complement proteins present in the urine can initiated the destruction of pathogens The initial immune response to an antigen ............ The secondary immune response to the same antigen involves....... - Correct Answers Slow memory B and T cells How is a B-cell receptor similar to an antigen? - Correct Answers Antibodies and B-cell receptors can both bind to antigen why does antibody concentration fade over time with acquired passive immunotherapy but increase over time with acquired active immunotherapy? Select all that apply - Correct Answers Passive immunotherapy is direct injection of antibodies that can break down over time Active immunotherapy is direct injection of antigen so the person's own immune system responds to make antibodies How is a B-cell receptor similar to an antibody? - Correct Answers B-cell receptors and antibodies are bound to the surface of cells AND antibodies and B-cell receptors both bind to antigen Autoimmune disorders are characterized by immune destruction of self tissues. The underlying basis of these disorders is - Correct Answers an oversecretion of antibodies from memory B cells a man develops a respiratory infection caused by a virus. He is not given antibiotics and subsequently recovers after about two weeks. Which best explains why his body destroyed some of his own cells during the viral infection? - Correct Answers The complement cascade is initiated by viral proteins in the host and ultimately results in the death of host

Table 7.1 A disk-diffusion test using E. coli gave the following results: Disinfectant Zone of inhibition (mm) A 0 B 3. C 10 D 5 In Table 7.1, the zone of inhibition is a measure of - Correct Answers the diameter of the area where E. coli growth is prevented. What can you conclude about Neisseiria gonnorrhoeae - Correct Answers The cell wall .......... in the figure, which diagram of a cell wall possesses lippolysaccharide molecules responsible for symptoms associated with infection? - Correct Answers b which of the following statements describe Gram-negative bacteria? - Correct Answers contains lippolysaccharides Burt is attempting to recreate pasteur's famous............ - Correct Answers Burt did not bring the broth to a full boil but left it at low heat for a long period of time which of the following is the best definition of generation time? - Correct Answers The length of time needed for a cell to divide the circulating substances that effect the hypothalamus and initiate fever are - Correct Answers pyrogens once inside the phagocyte, how are microbes killed? - Correct Answers lysozyme and digestive enzymes break apart the microbe in the phagolysosome the function of "ciliary escalator" is to - Correct Answers physically prevent the microorganism from exiting the host which of the following most accurately describes how a pathogen bacterium might be affected by antibodies? - Correct Answers the antibodies may

block proteins necessary for the pathogen to bind to host, may coat the bacterium or may agglutinate bacteria human breast milk contains lactoferin...... - Correct Answers first, second and third lines of defense figure 1 shows the antibody response in a host following antigen expore.....

• Correct Answers the same antigen