2007 Final Exam

Bio 118
Final Exam                        
23 April 2007

At the end of the exam bring the following to the proctor at the front of the room:

                  Your scantron
                  Your exam sheet
                  Your student ID or equivalent

Make sure the form number on the scantron matches that on the exam sheet!


Good luck to you all.

1. The average human being with a healthy immune system
a)Carries no bacteria at all (i.e. is sterile from a bacteriological point of view)
b)Carries some bacteria, but only non-pathogenic ones
c)Carries some bacteria, but only pathogenic ones
d)Carries a mix of pathogenic and non-pathogenic bacteria and would be sicker if they were all removed
e)Carries a mix of pathogenic and non-pathogenic bacteria and would be healthier if they were all removed

2. What is an antibody?
a)A cell that can be infected by HIV
b)A complex molecule that can recognize a specific antigen
c)A chemical that kills bacteria
d)A cell that engulfs and digests foreign substances in the blood
e)A drug that inhibits viruses by blocking their ability to replicate their nucleic acid.

3. During the late 1800’s many Europeans believed that human diseases were caused by poisonous vapors rising from rotting material that were capable of initiating disease in people who breathed them.Such vapors were known as
a)The four humours
b)Earth, wind, fire, and water
c)Evil spirits
d)Nocturnal emissions

4. When you go for an HIV test and an ELISA test is performed, the test is looking for the presence of
a)HIV viral particles in the blood
b)HIV-derived nucleic acid (RNA) in the blood
c)HIV-specific antigens in the blood
d)HIV-specific DNA inserted into the chromosomes of the T and B cells in lymph nodes
e)HIV-specific antibodies in the blood

5. Which of these would be characteristic of Bubonic Plague?
a)Black-appearing swellings of lymph nodes
b)Disfiguring pustules that form on the face and torso and that leave disfiguring scars for life on the survivors of the infection
c)A latent stage of several years during which there are no symptoms followed by a steady progression of symptoms leading to death unless treated
d)Severe diarrhea
e)A “healthy carrier” state with individuals who never show symptoms, but remain infectious

 6. As of January 2006, the percentage of the total HIV infections that occurred by “casual contact” in North America was
b)About 0.01%
c)About 0.1%
d)About 1%
e)About 4-5%

7. If you sprayed a pasture with pathogenic bacteria and found that the field was still dangerous 100 years later, that bacterium was probably the cause of
a)Typhoid Fever

8. The only disease organism ever to have been completely eradicated from the earth is
a)Salmonella typhi
b)Vibrio cholerae
c)Variola major
d)Bacillus anthracis
e)Treponema pallidum

9. The most common mode of HIV transmission worldwide is
a)Injection drug use
b)Breast milk
c)Sexual intercourse
d)Insect bites
e)Blood transfusions

10. Which of these is true of every known virus
a)It causes a disease in some plant, animal, or microbe
b)It is enclosed by a layer of cell membrane
c)It carries both some protein and some nucleic acid
d)It can survive drying and exposure to sunlight for decades or even centuries
e)It can be killed by the same antibiotics that kill bacteria

11. With what disease do we associate the old adage “One night with Venus, the rest of your life with Mercury?”
a)Genital Herpes

12. Cleve Jones, Larry Kramer, and Paul Popham would best be described as
a)Public health workers
b)Research scientists
c)Elected politicians
d)AIDS activists
e)Physicians who treat(ed) AIDS patients

13. One “modern” disease resembles syphilis in two ways: it is caused by a germ that is related to the syphilis germ, and it goes through several stages with different symptoms.That disease is
b)Lyme Disease
c)Legionnaire’s Disease
d)Toxic shock syndrome
e)Avian influenza

14. In his investigations of Typhoid Mary’s role in the outbreak of Typhoid Fever in Oyster Bay, George Soper concluded that the most likely source of the contamination that led to the infection of the household members was
c)Bed linens
d)Aerosols from coughs and sneezes
e)Shared toilet facilities

15. The term “Bug Chaser” refers to
a)Scientists who track down the cause of bacterial, viral, and fungal diseases
b)People who ostracize individuals with HIV/AIDS and drive them from their schools and neighborhoods
c)Law firms that seek out HIV/AIDS victims and file frivolous lawsuits in hopes of getting cash settlements to which they are not entitled
d)People who are trying to become infected with HIV
e)Men who regularly have sex with other men but deny being homosexual

16. The death of two adolescents (and severe disability of another) from Creutzfeldt-Jakob Disease in the UK, all within a one-year period, “sounded alarm bells” because
a)They were all in the same hospital at the same time, raising the possibility of a new epidemic arising
b)All three were from rich, powerfully connected families
c)A direct link was made between a particular food processing plant and each of the three, showing that the food supply was contaminated
d)Creutzfeldt-Jakob Disease is extremely rare in young people
e)Their youth raised a “human interest” element in media coverage that finally brought serious attention to a problem that had been obvious for some time

17. We are certain the “Typhoid Mary” was a healthy carrier of Typhoid Fever because
a)The New York City Public Health Laboratory identified Salmonella typhi in her stool samples over an extended period of time
b)Epidemiological tracking showed that she was present in at least six households where Typhoid Fever occurred
c)Soon after she was identified as a possible source of Typhoid Fever outbreaks, she developed a very serious case of Typhoid Fever herself
d)Both her parents had died of Typhoid Fever and two of her three siblings also suffered severe cases of Typhoid Fever
e)Her symptoms, as described at the time, match perfectly the symptoms of Typhoid Fever as we know them now

18. HIV-2 differs from HIV-1 in a number of properties. Among these is the fact that
a)HIV-2 is more common in the US than HIV-1
b)HIV-2 appears to have originated in pigs whereas HIV-1 appears to have originated in monkeys
c)Persons infected with HIV-2 progress to AIDS more slowly than persons infected with HIV-1
d)HIV-2 infections can be cured but HIV-1 infections cannot
e)HIV-2 uses DNA as its genetic material whereas HIV-1 uses RNA

19. Who was Selma Dritz?
a)A European surgeon who contracted HIV while working in Africa and was one of the first people in Europe to die of AIDS
b)A physician in New York City who lobbied for more support for AIDS research while still treating AIDS patients
c)A researcher in France who was the first to see HIV in the electron microscope
d)A public health worker in San Francisco who kept track of connections between different AIDS patients in the San Francisco Bay area
e)A comedienne who raised more private money for AIDS research one year than the entire federal budget for AIDS research in that year

20. If your tuberculin skin test results in a large, red welt, that means that
a)You are a carrier of drug resistant tuberculosis germs
b)You have had active tuberculosis at some time
c)You have been exposed to tuberculosis and infected by the germ
d)You have never been infected with tuberculosis germs
e)You are no longer immune to tuberculosis and need to be re-vaccinated

21. What is the CD4 protein?
a)A protein lacking in people who have been repeatedly exposed to HIV but never infected
b)A protein present on a small number of cell types that is absolutely required for HIV infection
c)A protein present on macrophages but not on T cells that is responsible for the conversion of HIV from M-tropic to T-tropic
d)A protein present on T cells but not on macrophages that is responsible for the conversion from M-tropic to T-tropic
e)A protein on HIV that recognizes the CCR5 receptor

22. In the absence of any treatment whatsoever, which of the following has the lowest mortality (probability that an infected individual will die of the infection)?
a)Typhoid Fever
b)Cholera (influenza is the real answer because rehydration therapy is a treatment, but some of you may have misunderstood “absence of any treatment whatsoever”)

23. The most common opportunistic infection of AIDS patients is
a)Kaposi’s sarcoma
b)Pneumocystis carinii pneumonia
c)Oral candidiasis (Thrush)

24. The proper use of a latex condom during sexual intercourse can reduce transmission of HIV
a)To zero
b)By a factor of between 3 and 10
c)By a factor of about 100
d)By a factor of about one thousand
e)To about 1 in 2 million

25. The program that eventually evolved into the Tuskeegee Study would have
a)Involved many fewer test subjects than the Tuskeegee Study
b)Been confined to the southern states
c)Focused on alcohol abuse almost exclusively
d)Required a larger military force than was used in the Tuskeegee Study
e)Intentionally infected the test subjects

26. One of the earliest drugs used to treat AIDS was

27. When the Secretary of Health and Human Services announced that an American team had isolated the virus that causes AIDS, there was an uproar of protest.The truth of the matter is that
a)Robert Gallo and his colleagues actually were the first to isolate the virus
b)Luc Montagnier and his colleagues were the first to isolate the virus and the virus Gallo isolated was actually Montagnier’s
c)Robert Gallo’s group and Luc Montagnier’s group isolated different HIV strains almost simultaneously
d)The virus that the American team isolated was not HIV, but rather another unrelated herpes virus that was carried by the AIDS patient from which the sample was taken
e)Don Francis’ group had isolated HIV and the secretary gave credit to Robert Gallo’s group

28. In 1997 Richard Rhodes published a book that outlined the hunt for the cause of a disease called Kuru and the links between variant Creutzfeldt-Jakob Disease and Mad Cow Disease in Great Britain.That book is
a)Plagues and Peoples
b)Deadly Feasts
c)Silent Spring
d)The Coming Plague
e)And the Band Played On

29. The name of George Soper will forever be associated with the name of
a)Robert Gallo
b)Ronald Reagan
c)John Snow
d)Robert Koch
e)Mary Mallon

30. Which of these would you find if you had an HIV virion to look at
a)A prion
b)Two pieces of single-stranded RNA
c)A bacterium
d)A piece of double-stranded DNA
e)A protein-free entity

31. Which form of genetic material is used by all humans, all bacteria, and even some viruses?
a)Double stranded DNA
b)Double stranded RNA
c)Single stranded DNA
d)Single stranded RNA

32. If a single bacterium were to split into three new bacteria every twenty minutes, how many bacteria would there be after 2 hours?
e)more than 2,000

33. T cells (especially T4 helper cells) are an important component of our blood because they can (among other things)
a)Activate macrophages to be more aggressive
b)Carry oxygen to the tissues
c)Lead to regeneration of bone and bone marrow
d)Can resist infection by HIV
e)Can cross the blood-brain barrier with ease

34. The antibody factories in the body are the mature versions of
a)B cells
b)T4 helper cells
c)T8 killer cells
e)Red Blood cells

35. The acidity of the fluids in your stomach is a partial defense against infection by
a)Mycobacterium tuberculosis
b)Vibrio cholerae
c)Treponema pallidum
d)Bacillus anthracis
e)Influenza virus

36. At present (2007) your risk of contracting HIV from a blood transfusion is about one in
a)Two hundred thousand
b)Two million
c)Twenty million
d)Two hundred million
e)Two billion

37. The rise of capitalism is sometimes linked to the effects of
a)The depopulation of Europe by the Black Death
b)The importation of syphilis from the New World
c)The depopulation of North America by Old World diseases
d)The influenza pandemic of 1918-1919
e)The discovery of bacterial causes of many diseases by Koch and Pasteur

38. The current number of people worldwide who are living with HIV infections is in the
a)Hundreds of thousands
c)Tens of millions
d)Hundreds of millions

39. A few years ago, a white powder was sent through the US Mail, and the result was that several people died and others were gravely ill.What organism was contained in the white powder?
a)Salmonella typhi
b)Vibrio cholerae
c)Yersinia pestis
d)Bacillus anthracis
e)Variola major

40. If smallpox broke out in Ann Arbor and no vaccination were available, what fraction of the population would die?
a)Less than 1%
b)About 1%
c)About 5%
d)About 30%
e)About 95%

41. In the time before seroconversion (scoring positive in the ELISA test), an HIV-infected individual is probably
a)Not infectious
b)Less infectious than a seropositive individual
c)About as infectious as a seropositive individual
d)More infectious than a seropositive individual
e)Resistant to infection by viruses other than HIV

42. Which of these has the smallest number of genes?
a)A bacterium
b)A human
c)A tree
d)A yeast
e)A virus

43. The Europeans who came to the New World found no dinosaurs there.This is because
a)There never were any dinosaurs in the New World; they were restricted to the Old World
b)They died out before humans evolved
c)They died out because of human diseases brought by the first humans who crossed into the New World via Alaska
d)They died out because of diseases brought by the “Columbian Exchange” before the Europeans ever saw them
e)They were exterminated by early hunters soon after the technological innovation known as the “Clovis Spear Point”

44. Kaposi’s Sarcoma was one of the common clinical manifestations of AIDS, especially among gay men.What is Kaposi’s sarcoma?
a)A fungal infection of the mouth and throat
b)A cancer that shows itself as purple patches on the skin
c)A bacterial infection that results in the developmental on the skin of tumor-like lumps that are well supplied with blood vessels
d)A swelling of the lymph nodes
e)A profound weight loss coupled with “night sweats”

45. The first country in the New World to experience a high incidence of HIV/AIDS was
c)Puerto Rico

46. What is the Wasserman test?
a)Another name for the tuberculin skin test
b)A complement fixation assay for syphilis
c)An ELISA test for HIV
d)An antibody assay for Typhoid Fever (also called a Widal reaction)

47. The father of “shoe leather epidemiology,” famous for his map showing the location of every case of a particular disease, is
a)Louis Pasteur
b)Robert Koch
c)Alexander Yersin
d)George Soper
e)John Snow

48. Someone who is “on the down low” is
a)A man who is having sex with other men
b)A person who is suffering from depression related to AIDS dementia
c)A person who is losing control of his or her life because of injection drug use
d)Any person at the bottom of a socio-economic hierarchy
e)A person living with AIDS

49. Bovine spongiform encephalopathy (BSE or “Mad Cow Disease”) was not considered to be a risk to the human population because
a)Scrapie was known not to affect humans
b)Anthrax was not seen in Great Britain except for the experiments on Gruinard Island
c)Stomach acid rapidly inactivates the causative agent
d)It is caused by a prion

50. Filtration of water supplied to cities was a key step in eliminating most of the outbreaks of several diseases, including
a)Typhoid Fever
c)Bubonic Plague

51. The number of new HIV infections per yearin the United Statesis about

52. Where was the disease Kuru first identified?
c)New Guinea
d)New Zealand
e)Central Africa

53. What made Francoise Barre so special?
a)She was the first “healthy carrier” of typhoid fever in the US
b)She was the first “healthy carrier” of typhoid fever in the world
c)She is the woman who first grew HIV (which she and her colleagues called LAV)
d)She noticed an unusually high number of orders for a restricted drug and was the first person at the CDC to suspect that something new (AIDS) was happening in New York
e)She was the first person in the world whose diagnosis of Typhoid Fever was confirmed by a bacteriological test

54. Arye Rubinstein’s views about AIDS were not believed in the early days of the AIDS epidemic in the United States.Where would you have been most likely to find Ayre Rubenstein at that time?
a)A pediatrics ward in New York
b)A bath house in New York or California
c)A research lab in France
d)A Red Cross blood bank office
e)Doing fieldwork for the CDC

55. The man who first identified the bacillus that causes Tuberculosis was
a)Robert Koch
b)Louis Pasteur
c)George Soper
d)John Snow
e)Alexander Yersin

56. The influenza that caused the 1918-1919 pandemic was unusual in that it killed
a)20-40 year olds instead of infants and old people
b)20-40 year olds in addition to infants and old people
c)Infants and old people instead of 20-40 year olds
d)Infants and 20-40 year olds instead of old people
e)Old people and 20-40 year olds instead of infants

57. Which of these is most likely reduce the probability of transmission of HIV from female to male during vaginal intercourse?
a)Spermicidal lubricants like Nonoxynol 9
b)Circumcision of males
c)”Circumcision” of females
d)The presence of other competing bacterial or viral infections
e)The ambient temperature

58. Throughout most of the period of the Tuskeegee Study, the test subjects were told that they were being treated for
a)Bad blood
b)Iron deficiency anemia
e)Slim disease

59. For what fraction of AIDS patients is the current multi-drug treatment effective?
a)Less than 10%
b)About 30%
c)About 50%
d)About 70%
e)More than 95%

60. Which of the following is NOT true of Don Francis?
a)He was trained as a virologist
b)He worked for the CDC
c)He worked in the program that eradicated smallpox
d)He died of AIDS

61. The Secretary of Health and Human Services who, during the Reagan Administration, argued over and over that the scientists were getting all the money they could use, even though she knew that to be untrue was
a)Francoise Barre
b)Mary Guinan
c)Margeret Heckler
d)Mathilde Krim
e)Grethe Rask

62. Amyloids (associated with kuru) are made of
b)Nucleic acids
c)Dead human cells
d)Dead bacteria
e)Dead viruses

63. The main role in the immune response of a dendritic cell is to
a)Secrete chemicals that cause a particular T cell to undergo clonal expansion
b)Carry antigens to the lymph nodes where they can interact with B and T cells
c)Cause T cells that might recognize your own tissues to commit suicide before leaving the thymus
d)Carry antibodies to the site of an infection or inflammation
e)Determine whether an immature T cell will mature into a T4 helper cell or a T8 killer cell

64. One of your body’s defenses against microbial invaders is the complement system.The role of complement is to
a)Punch holes in the cell membrane of invaders
b)Produce antibodies
c)Engulf invaders and digest them
d)Cause clonal expansion of specific classes of T cells
e)Present antigens to T cells

65. Stanley Prusiner was a scientific competitor of
a)Luc Montagnier
b)Robert Koch
c)Carlton Gajdusek
d)Herman Biggs
e)Robert Gallo

66. Blindness sometimes occurs as a result of AIDS. This blindness is most often the result of an opportunistic infection by
a)Mycobacterium tuberculosis (TB)
b)Mycobacterium avium complex (MAC)
c)Cytomegalovirus (CMV)
d)Human Herpes Virus 8 (HHV8)
e)Candida albicans

67. Fecal-oral transmission is the most common route for transmission of
a)Typhoid Fever
c)Bubonic Plague

68. Which of these are least alike (i.e. most distantly related evolutionarily)?
a)An Oak Tree and a human being
b)A human being and Candida albicans
c)Candida albicans and Salmonella typhi
d)A chimpanzee and a starfish
e)A dinosaur and a bird

69. In the absence of antibiotics, the effectiveness of “rehydration therapy” in treating Cholera is about
a)Zero (less than 2%)
e)95% or more

70. With which of these disease organisms is the greatest number of people currently infected (i.e. currently have the organism in them)?
a)Salmonella typhi
b)Vibrio cholerae
c)Mycobacterium tuberculosis
d)Treponema pallidum

71. What is the primary difference between Bubonic Plague and Pneumonic Plague
a)Their causative agent (a bacterium vs. a virus)
b)Their route of transmission (flea bites vs. aerosols)
c)Their geography (Asia vs. Europe)
d)Their history (Pneumonic during Roman Empire, Bubonic after 1346)
e)Bubonic is the disease after the first infection, Pneumonic is a reoccurrence years later when your immune system weakens from age, nutrition, or other diseases

72. Which of these diseases is caused by a toxic protein (a toxin) that is secreted by a pathogenic bacterium?

73. The most lethal pandemic of influenza in history occurred
a)Just before the fall of the Roman Empire
b)During the mid 1300’s
c)Near the end of the Napoleonic Wars
d)At the end of World War I
e)At the end of World War II

74. The terms “variolation” and “vaccination” originated in connection with what disease?a)Typhoid Fever

75. A virus that makes a DNA copy of its RNA is called
a)A retrovirus
b)A pathogenic virus
c)A cancer virus
d)An AIDS virus
e)A bacterial virus

76. The term “Columbian Exchange” generally refers to
a)The hostages left by Columbus with the natives on Santo Domingo when he took several of the native nobility back to Europe
b)The high correlation between cocaine usage and HIV infection in the US
c)The transport of slaves from the Old World to the New World and the transport of gold from the New World to the Old World
d)US support for Panama’s independence from Columbia in exchange for the right to build the Panama Canal
e)The transport of plants, animals, and diseases native to the Old World to the New World and those native to the New World to the Old World

77. The first American cases of the disease we now know as AIDS were identified in
a)The early 1990’s
b)The early 1980’s
c)The early 1970’s
d)The early 1960’s
e)The early 1950’s

78. HIV/AIDS is characterized by an initial infection with mild symptoms that are often missed or misdiagnosed, followed by a long latent period with no symptoms whatsoever, followed by the onset of serious symptoms which, if untreated, lead invariably to death.This is also true of
a)Typhoid fever

79. With which socio-political movement of the 1930s and ’40s would the “Tuskeegee Study” be associated?
c)Women’s suffrage
d)Social hygiene

80. Typhoid Mary was ultimately returned to North Brother Island because
a)She was unable to pay her rent and was charged with vagrancy
b)She had returned to cooking and caused another outbreak of Typhoid Fever
c)She escaped from custody in a minimal security confinement center
d)She was dead and wished to be buried there
e)She needed to be protected from angry mobs who had threatened her life

81. The ultimate cause of the Cholera outbreak in Golden Square, London was contaminated water in the Broad Street Pump.The source of that contamination was later found to be
a)Infiltration of the drinking water with water from the Thames river, downstream of London
b)Broken pipes from a water company that did not purify its water
c)A baby’s diaper and wastewater that leaked from a nearby cesspool
d)Sailors of the Baltic Sea fleet who drank from the pump and contaminated it
e)Rainwater that disturbed the construction site, which in turn had disturbed an old burial ground dating back to the plague years.

82. The disease “Kuru” was first identified by
a)Carlton Gajdusek
b)Robert Koch
c)John Snow
d)George Soper
e)Richard Rhodes

83. The germ that causes Typhoid Fever can enter (and remain in) a carrier state because
a)Some people have no T4 cells that recognize it and thus cannot raise a specific immune response to it
b)It lodges in tissues that are not well-supplied with blood or lymph and thus rarely come in contact with cells and proteins of the immune system
c)It prevents fusion of the lysosome with the phagosome and thus escapes destruction in the phagocyte
d)It can cross the blood-brain barrier and thus be maintained in a compartment where normal inflammatory responses do not occur
e)It forms spores that can persist in the body for years or even decades because the spores are resistant not only to heat and drying, but also to cellular defenses.

84. Africa is the continent where the first
a)Healthy carrier of Typhoid Fever in the world was identified
b)Outbreaks of the current H5N1 Avian Influenza were detected
c)Human infections by HIV occurred
d)Documented case of what we now know as Bubonic Plague occurred
e)Cases of “Spanish Flu” occurred

85. People who lack a particular protein on the surface of their cells are almost never infected with HIV despite multiple sexual contacts with an infected partner.That missing protein is
d)Reverse transcriptase

86. Even before AIDS was identified, Sandra Ford at the CDC noticed an unusually high number of orders for a special drug, pentamidine, and wondered why so many people in New York were coming down with
a)Cytomegalovirus infections
b)Kaposi’s sarcoma
d)Pneumocystis carinii pneumonia
e)Mycobacterium avium complex

87. A macrophage is able to take up a whole bacterium, digest it to small pieces, attach those pieces to a “self” molecule (also called MHC), and then put this combination of “self” and small piece onto the surface of a cell.This process is called
b)T-cell maturation
c)Antigen presentation
d)Antibody binding
e)Complement fixation

88. In most HIV infected adults, the initial stage (“window period”) before appearance of HIV-specific antibodies in the blood lasts for
e)Indefinitely (most never develop antibodies that will bind to HIV)

89. When speaking of HIV/AIDS, the term “viral load” refers to
a)The number of different opportunistic infections you have had since becoming infected with HIV
b)The number of sexually transmitted infections (related to “gay bowel syndrome”) you had leading up to infection with HIV
c)The molecular weight of the particular strain of HIV with which you have been infected
d)The concentration of HIV in your blood
e)The amount of metabolic energy required above and beyond that required for an uninfected person to stay alive

90. Which of these diseases is caused by a virus?
c)Kaposi’s sarcoma

91. Which of these activities is most likely to lead to transmission of HIVfromyour HIV positive partner?
a)Receptive vaginal intercourse
b)Insertive vaginal intercourse
c)Receptive anal intercourse
d)Brachioproctic manipulation (“Fisting”)
e)Anilingus (“Rimming”)

92. The term “Herd Immunity” implies that
a)Viral diseases can be transmitted from animals to humans, but not from humans to animals
b)The source of the epidemic was a disease that is lethal for humans but harmless to the animals in which it originated
c)If the probability that a given contact between two individuals will result in transmission can be reduced enough, an epidemic will not be self-sustaining
d)A group (“herd”) of animals of a single (domesticated) species is less likely to be susceptible to an epidemic disease than a group (“community”) of animals of many different species
e)A large number of individuals need to become infected for an epidemic to begin in the first place

93. The most common acronym for the multi-drug regimen currently in use to treat AIDS is

94. Typhoid Fever and AIDS are both among the “reportable” diseases.This means that
a)Newspapers and other media are permitted to report not only its outbreak but also the names of the carriers
b)Those diagnosed with these diseases must report at regular intervals to health officers for testing and counseling
c)Physicians are required to report all cases to public health authorities
d)Public health officials are required by law to report any local outbreaks of these diseases above the “normal” background level of incidence
e)Medical journals still accept articles investigating outbreaks of these diseases

95. During the 1970s and 80s there was a serious problem with Hepatitis in the gay male population of San Francisco.Many gay men gave blood samples as part of a study of the spread of the disease and as part of the development of a vaccine against Hepatitis.  An unplanned side-effect of this blood sampling was that
a)It allowed the epidemiological analysis of the spread of HIV, which entered the population during the period when the blood sampling was done
b)It showed that the presence of the hepatitis virus was partially protective against HIV
c)A significant number of the early HIV infections were actually the result of an inadequate sterilization of the needles used to sample blood, resulting in blood transfer from one person to another
d)It identified the genetic marker that is associated with homosexuality in about 30-50% of all homosexual men
e)Men who tested positive for hepatitis lost their health insurance

96. The prion hypothesis claims that a disease can be transmitted by an agent that contains
a)DNA, RNA, and protein
b)Protein and DNA, but no RNA
c)Protein, but no DNA or RNA
d)DNA, but no protein or RNA
e)DNA and RNA, but no protein

97. What caused Mary Mallon’s death
e)Typhoid Fever

98. HIV carries a protein that can insert the DNA copy of HIV’s RNA into the chromosomes of a cell.This protein is the HIV
c)Reverse transcriptase

99. Drugs like streptomycin and penicillin can be effective in inhibiting
a)Bacterial growth
b)Retroviral replication
c)Influenza virus spread
d)Transmission of HIV from mother to child during childbirth
e)Death of T-cells in culture

100. When an antibody binds to an antigen and when a normal PrP is converted into a pathogenic prion, both undergo
a)Degradation in vesicles after the vesicles fuse with lysosomes
b)Conformational change
d)Conversion to a DNA copy and integration in the chromosomes of the cell
e)Perigradular fraglitation

101. The cell-type within the immune system on which all other cell types depend for the signal that leads to clonal expansion is the
a)T4 helper cell
b)T8 killer cell
c)B cell
e)Dendritic cell