Micro exam 1 PDF

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Exam 1 1. What best describes a ‘ Microbe’ ? (Lecture 1) a. A form of life that is relatively simple. b. A form of life that can make an animal sick. c. A form of life that requires a microscope to observe. d. A form of life that consists of a single cell. Answer: _____

2. The size of a typical bacterium is approximately 1 micron (also known as a μm or micrometer). To observe a bacterium, at a minimum one requires… (Lecture 1) a. Normal 20/20 vision. b. A light microscope. c. An electron microscope. d. It’ s not possible to observe bacteria, even with the most powerful microscopes. Answer: _____

3. All of us are composed of approximately equal numbers of human and microbial cells (3 x 1013 each). The microbial cells in a human body are distributed…(Lecture 1) a. primarily in the upper intestinal tract (stomach and small intestine). b. primarily in the lower intestinal tract (the large intestine/colon). c. primarily on the surface of the skin. d. evenly along all surfaces of the skin and intestinal tract. Answer: _____

4. Earth is over 4 billion years old. Microbes…(Lecture 1) a. have existed for about 0.1 billion (100 million) years. b. have existed about as long as animals (0.6 billion years).

c. have existed for about 1.5 billion years. d. have existed for about 3.8 billion years. Answer: _____

5. Microbes were discovered about ____ years ago but were shown to cause diseases ____ years ago. (Lecture 1) a. 100 ; 40 b. 350 ; 140 c. 3,500 ; 350 d. 10,000 ; 1,000 Answer: _____ 6. Which situation of death represents best that the immune system plays a critical role for our survival? (Lecture 2) a. Murder victim by strangulation. b. Death in car accident. c. Death following septicemic plague. d. Death of an HIV/AIDS patient by an opportunistic microbe. Answer: _____

7. Which of the pairs below portrays a barrier function that was breached by the indicated pathogen prior to the infection? (Lecture 2) a. Mucociliary escalator –influenza b. Action of lysozyme in tears –HIV c. Stomach acidity –Yersinia pestis d. Antimicrobial molecules produced by the skin –Vibria cholera

Answer: _____

8. Which statement about blood and its components is correct? (Lecture 2) a. It contains more white blood cells than red blood cells per ml.

b. Health professionals analyze some of its cells and serum components to assess the status of the immune system. c. Every infection leads to pathogens traveling in the blood system. d. Only the cells, but not the serum, contain immunologically important components. Answer: _____

9. The immune system is able to protect us from many infectious diseases with both microscopically small and large pathogens, but its brilliant complexity makes it susceptible to “ programming errors”that cause a disease itself. An example for such a disease is: (Lecture 2) a. Provision of immunity following vaccination. b. Defeat of cancerous cells. c. Allergic response. d. HIV infection. Answer: _____

10. What is a unique ability of the adaptive immune system that the innate immune system cannot provide? (Lecture 3) a. It has “ millions”of cells waiting in the body to become activated by the pathogen. b. It kills pathogens. c. Cells are recruited to the site of an infection. d. It generates immunological memory. Answer: _____

11. Macrophages can perform many functions, EXCEPT (Lecture 3) a. migrate to the draining lymphnodes. b. take up bacterial pathogens and digest them. c. recognize bacterial products such as LPS. d. “ plugg”the holes of an injured barrier.

Answer: _____

12. The plague bacterium, Yersinia pestis, infects humans via the bite of a flea. How does this pathogen prevent an aggressive inflammatory response at this initial point of infection? (Lecture 3) a. It stops making LPS so not to activate toll like receptors (TLRs). b. It makes an altered form of LPS that has reduced binding to TLRs. c. It uses a protein injection system to paralyze immune cells. d. It releases a toxin that causes the surrounding tissue to become very salty. Answer: _____

13. In the early phase of infection immediately following gaining access to the tissue (i.e., just after the flea bite), how does Yersinia pestis avoid getting killed by the resident macrophages? (Lecture 3) a. It invades these macrophages and immediately kills them. b. It uses a protein injection system to paralyze these macrophages. c. It invades these macrophages but avoids being exposed to the contents of the lysosome. d. It releases a toxin that kills macrophages and other immune cells. Answer: _____

14. Later in infection once it had traveled to the lymph node, Yersinia pestis, switches strategy and starts to… (Lecture 3) a. It stops making LPS so not to activate toll like receptors (TLRs). b. It makes an altered form of LPS that has reduced binding to TLRs. c. It uses a protein injection system to paralyze immune cells. d. It releases a toxin that causes the surround tissue to become very salty. Answer: _____

15. All the following describe Gram positive and Gram negative bacteria EXCEPT: (Lecture 4) a. Gram positive bacteria have a much thinner peptidoglycan layer. b. Only Gram negative bacteria possess an outer membrane. c. They differ in how well they retain crystal violet stain; this is the basis of the Gram stain. d. Both Gram negatives and positive can cause diseases in humans. Answer: _____

16. Jose is a microbiologist studying Yersinia pestis using a mouse model of infection. He makes an educated guess that a particular Yersinia pestis gene (let’ s call it ‘ gene X’ ) may encode a virulence factor. Jose then makes a mutant strain that lacks gene X. In the mouse infection model, this mutant strain has approximately the same Lethal Dose 50% (LD50) as the ‘ wild-type’ strain (that possesses a normal gene X).Based on this finding, what can Jose conclude?(Lecture 4) a. Gene X encodes a virulence factor (at least by this method of testing). b. Gene X does not encode a virulence factor (at least by this method of testing). c. There is not enough information to decide if Gene X encodes a virulence factor. d. Jose was mistaken to think that LD50 measurements have anything to do with virulence factors. Answer: _____

17. We discussed how a ‘ genetic screening’approach can be used to discover bacterial virulence factors. What was the critical step in this approach? (Lecture 4) a. Isolating pathogens from sick individuals. b. Identifying genes in the bacterial chromosome that were similar to known virulence factors in other pathogens. c. Transferring small pieces of the bacterial chromosome from the pathogen to an unrelated bacterium. d. Determining the LD50 of the pathogen.

Answer: _____ 18. The pathogen Vibrio cholerae causes the disease cholera. What is the chronological order of events that occur during this disease? (Lecture 4) a. A toxin is ingested → The toxin causes the intestines to constrict → Disease symptoms caused by blockage of intestine b. The pathogen is ingested → A toxin is released that causes the pathogen to ‘ stick’to the cells lining the intestine → Disease symptoms are then caused by the pathogen producing pili that kill intestinal cells c. The pathogen is ingested → Pili help the pathogen to ‘ stick’ to the cells lining the intestine → The pathogen releases a toxin → Disease symptoms are caused by the toxin making the lumen of the gut less salty d. The pathogen is ingested → Pili help the pathogen to ‘ stick’ to the cells lining the intestine → The pathogen releases a toxin → Disease symptoms are caused by the toxin making the lumen of the gut more salty Answer: _____

19. Helicobacter pylori is a neutralophile which means it survives and grows best at neutral pH (~7). In the late 1980s it was puzzling how this bacterium could be a stable inhabitant of the stomach of most humans. What is the clever trick of how Helicobacter pylori ‘ solves’this problem? (Lecture 5) a. It invades the cells lining the stomach thereby shielding itself from the stomach acid. b. It actually makes its way to the gall bladder and from there can continually be reintroduced into the intestinal tract. c. It synthesizes urea which is used to neutralize stomach acid. d. It breaks urea down and one of these breakdown products, ammonia, neutralizes stomach acid. Answer: _____

20. According to the CDC website, bacterial meningitis is a relatively ____ disease that can be caused by ____ pathogen(s). (Lecture 5) a. mild; only one b. mild; several different

c. severe; only one d. severe; several different Answer: _____

21. All of the following statements are true about Salmonella-caused gastroenteritis and typhoid fever in humans EXCEPT: (Lecture 5) a. Both S. enterica Typhimurium and S. enterica Typhi use a type 3 secretion system (encoded by SPI-1) to invade cells. b. Both S. enterica Typhimurium and S. enterica Typhi use a type 3 secretion system (encoded by SPI-2) to grow inside macrophages. c. S. enterica Typhimurium is usually contained with the initial infection area whereas S. enterica Typhi can, at least in a small percentage of infected individuals, escape from the initial infection site and colonize other tissue. d. S. enterica Typhimurium and S. enterica Typhi can only cause acute disease, neither can ever establish a chronic disease.

Answer: _____

22. Which statement explains why microbiologists who work in the food-producing industry pay particularly close attention to Listeria monocytogenes? (Lecture 5) a. It can be genetically modified. b. It is an intracellular pathogen. c. Listeria can grow at 4°C (refrigerator). d. Listeria can cross the intestinal and placental barriers. Answer: _____

23. An infectious agent thought to be a virus is isolated. Which of the following characteristics indicate that it is NOT a virus? (Lecture 6) a. Is surrounded by an envelope

b. It is dependent on the host cells for energy production c. Contains both RNA and DNA d. Contains enzymes Answer: _____

24. A unique characteristic of prions not shared with any other infectious agents is that they (Lecture 6) a. Do not cause human disease b. Are composed solely of protein c. Generate metabolic energy d. Are mostly plant pathogens Answer: _____

25. Regarding rabies virus (Lecture 6) a. It spreads in the body after infection via the bloodstream b. A live virus vaccine is required to be given to all children of school age c. When the virus reaches the central nervous system and the symptoms of the disease are apparent, is almost always fatal d. In the USA, the main source are mice Answer: _____

26. The influenza flu virus (Lecture 7) a. uses its hemagglutinin protein to bind to host cells and infect them. b. uses its hemagglutinin protein to infect red blood cells. c. causes minor disease symptoms as compared to other viruses that infect the respiratory tract. d. has its genomic information organized within a circular plasmid inside its nucleocapsid.

Answer: _____

27. Upon the infection of an individual with an influenza A virus, (Lecture 7) a. antibodies against hemagglutinin appear within 48 hours in the serum. b. antibodies against hemagglutinin will provide the individual with lifelong immunity against the flu. c. antibodies against neuraminidase can prevent the spread of the virus from one cell to another. d. antibodies against neuraminidase are assessed by the hemagglutination assay. Answer: _____

28. Your 24-year-old UM roommate hasn’ t felt well for the past few days and complains about runny eyes, a sore throat and the beginning of a cough. After staying at home all day today and watching non-stop cable news about a newly emerging swine flu in China, he is convinced that he will die within the next few days. Based on the recent discussion in your Microbes and the Immune System class, you decide to take action and advise him to implement some hygiene measures for your own protection. But you also let him know to stop worrying and change the channel to watch “ Grey’ s Anatomy”instead. All of the following reasons support your optimism, EXCEPT (Lecture 7) a. your roommate is a hypochondriac. b. your roommate is walking around in the apartment while he is watching TV. c. your roommate has a high fever and his muscles and joints are so painful that he doesn’ t leave the bed. d. Florida is depicted in green by the CDC’ s up-to-date map for flu-like infections. Answer: _____ 29. Which pair below fulfills all of the following: 1) It only comprises cells or weapons of the innate immune system; 2) The first cells or weapons participate in the defense of viral infections; and 3) The second cells or weapons participate in the defeat of bacterial infections. (Lecture 7) a. interferon alpha –B-cells/antibodies

b. macrophages –neutrophils c. cytotoxic T-cells –interferon alpha d. NK cells –macrophages Answer: _____

30. How is it possible that an individual with an intact immune system can be infected by influenza viruses within one year after the prior influenza infection? (Lecture 7) a. While true, there are no scientific explanations. b. Mutations in the hemagglutinin and neuraminidase genes render antibodies raised against the prior infection useless. c. Influenza infections persist just like HIV infections. d. Influenza infections block the generation of memory B -cells and T-cells. Answer: _____

31. Rubella virus (Lecture 8) a. Produces mostly a vesicular rash b. Can cause congenital malformations in the fetuses of pregnant mothers c. Is transmitted by arthropods d. Belongs to the Orthomyxovirus family Answer: _____

32. Regarding Paramyxoviruses (Lecture 8) a. Measles mostly infects the salivary glands b. Mumps is the major cause of juvenile diabetes in the U.S.A. c. Respiratory syncytial virus is the most important cause of severe lower respiratory tract infections in small children d. Current vaccines against measles, mumps and rubella have been proven to cause autism in young children Answer: _____

33. Rhinoviruses are Picornaviruses that (Lecture 8) a. Replicate well in the gastrointestinal tract b. Have 3 distinct serotypes c. After a primary viremia they invade the central nervous system d. Are the main cause of common colds

Answer: _____

34. Regarding Arboviruses all of the following statements are true EXCEPT (Lecture 8) a. Include dengue, Zika and yellow fever viruses b. Their natural hosts (reservoirs) can be birds c. Are usually transmitted by mosquitoes and ticks d. They are DNA containing viruses Answer: _____

35. Rotaviruses: (Lecture 8) a. Belong to a family of double stranded RNA containing viruses b. No vaccines are available against this viruses c. Disease can be significant in adults but asymptomatic in infants d. The virus has an outer envelope and cannot resist gastrointestinal conditions Answer: _____

36. Regarding hepatitis viruses (Lecture 8 & 9) a. There is no vaccine available against any Hepatitis virus b. Hepatitis D is a viroid-like agent containing RNA

c. Hepatitis C has a DNA genome d. Hepatitis B only causes mild disease all over the world Answer: _____

37. Naturally occurring smallpox was eradicated from the world because (Lecture 9) a. It has an exclusive human host range with no animal reservoirs or vectors and a single serotype b. Gives consistent disease presentation with visible pustules c. There is a stable, inexpensive, easy to administer vaccine d. All of the above Answer: _____

38. The infectious agent known to cause hand and anal warts and cervical carcinoma is: (Lecture 9) a. Papilloma virus b. Epstein-Barr virus c. Adenovirus d. Cytomegalovirus

Answer: _____

39. An INCORRECT statement about Parvoviruses: (Lecture 9) a. Are the smallest of all the DNA containing viruses b. Possess a single-stranded DNA genome c. Can multiply in resting cells without a need of a helper virus d. B19 is a human parvovirus that causes the “ fifth disease” Answer: _____

40. If you have shingles you must have previously had chickenpox which is caused by (Lecture 9) a. From another person with an acute case of Herpes zoster (varicella) b. A result of a previous infection with varicella (chickenpox) c. From a child with subclinical chickenpox d. From a chicken Answer: _____...