micro lecture exam 3 (taylor) Flashcards


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1

1. The emergence of new infectious diseases is probably due to all of
the following except

the need of bacteria to cause disease.

2

2. All members of a group of ornithologists studying barn owls in
the wild have had salmonellosis (Salmonella gastroenteritis). One
birder is experiencing her third infection. What is the most likely
source of their infections?

They are contaminating their hands while handling the
owls and nests.

3

3. Which of the following statements is false?

E. coli never causes disease.

4

4. Which of the following is not one of Koch’s postulates?

The disease must be transmitted from a diseased animal to a
healthy, susceptible animal by direct contact.

5

5. Which one of the following diseases is not correctly matched to its
reservoir?
a. influenza—human
b. rabies—animal
c. botulism—nonliving
d. anthrax—nonliving
e. toxoplasmosis—cats

influenza—human

6

On September 6, a 6-year-old boy experienced fever, chills, and
vomiting. On September 7, he was hospitalized with diarrhea and
swollen lymph nodes under both arms. On September 3, the boy had
been scratched and bitten by a cat. The cat was found dead on
September 5, and Yersinia pestis was isolated from the cat. Chloramphenicol
was administered to the boy from September 7, when
Y. pestis was isolated from him. On September 17, the boy’s
temperature returned to normal; and on September 22, he was
released from the hospital.
6. Identify the incubation period for this case of bubonic plague ?

September 3–5.

7

On September 6, a 6-year-old boy experienced fever, chills, and
vomiting. On September 7, he was hospitalized with diarrhea and
swollen lymph nodes under both arms. On September 3, the boy had
been scratched and bitten by a cat. The cat was found dead on
September 5, and Yersinia pestis was isolated from the cat. Chloramphenicol
was administered to the boy from September 7, when
Y. pestis was isolated from him. On September 17, the boy’s
temperature returned to normal; and on September 22, he was
released from the hospital.
7. Identify the prodromal (beginning) period for this disease ?

September 6–7.

8

A Maryland woman was hospitalized with dehydration; Vibrio
cholerae and Plesiomonas shigelloides were isolated from the patient.
She had neither traveled outside the United States nor eaten raw shell
fish during the preceding month. She had attended a party 2 days
before her hospitalization. Two other people at the party had acute
diarrheal illness and elevated levels of serum antibodies against Vibrio.
Everyone at the party ate crabs and rice pudding with coconut milk.
Crabs left over from this party were served at a second party. One of
the 20 people at the second party had onset of mild diarrhea; specimens
from 14 of these people were negative for vibriocidal antibodies.
8. This is an example of ?

vehicle transmission.

9

A Maryland woman was hospitalized with dehydration; Vibrio
cholerae and Plesiomonas shigelloides were isolated from the patient.
She had neither traveled outside the United States nor eaten raw shell
fish during the preceding month. She had attended a party 2 days
before her hospitalization. Two other people at the party had acute
diarrheal illness and elevated levels of serum antibodies against Vibrio.
Everyone at the party ate crabs and rice pudding with coconut milk.
Crabs left over from this party were served at a second party. One of
the 20 people at the second party had onset of mild diarrhea; specimens
from 14 of these people were negative for vibriocidal antibodies.
9. The etiologic (cause)agent of the disease is?

Vibrio cholerae.

10

A Maryland woman was hospitalized with dehydration; Vibrio
cholerae and Plesiomonas shigelloides were isolated from the patient.
She had neither traveled outside the United States nor eaten raw shell
fish during the preceding month. She had attended a party 2 days
before her hospitalization. Two other people at the party had acute
diarrheal illness and elevated levels of serum antibodies against Vibrio.
Everyone at the party ate crabs and rice pudding with coconut milk.
Crabs left over from this party were served at a second party. One of
the 20 people at the second party had onset of mild diarrhea; specimens
from 14 of these people were negative for vibriocidal antibodies.
10. The source of the disease was?

crabs.

11

The removal of plasmids reduces virulence in which of the
following organisms?

Streptococcus mutans

12

What is the LD50 for the bacterial toxin tested in the example
below?
Dilution
(μg/kg)
No. of Animals
Died
No. of Animals
Survived
a. 6 0 6
b. 12.5 0 6
c. 25 3 3
d. 50 4 2
e. 100 6 0

25 3 3

13

3. Which of the following is not a portal of entry for pathogens?

blood

14

All of the following can occur during bacterial infection. Which
would prevent all of the others?

vaccination against fimbriae

15

The ID50 for Campylobacter sp. is 500 cells; the ID50 for
Cryptosporidium sp. is 100 cells. Which of the following
statements is false?

Cryptosporidium is more virulent than Campylobacter.

16

An encapsulated bacterium can be virulent because the capsule

resists phagocytosis.

17

A drug that binds to mannose on human cells would prevent

the attachment of pathogenic E. coli.

18

The earliest smallpox vaccines were infected tissue rubbed into the skin
of a healthy person. The recipient of such a vaccine usually developed
a mild case of smallpox, recovered, and was immune thereafter. What
is the most likely reason this vaccine did not kill more people?

Skin is the wrong portal of entry for smallpox.

19

Which of the following does not represent the same mechanism
for avoiding host defenses as the others?

Rabies virus attaches to the receptor for the neurotransmitter
acetylcholine.

Salmonella attaches to the receptor for epidermal growth factor.

Epstein-Barr (EB) virus binds to the host receptor for
complement.

Surface protein genes in Neisseria gonorrhoeae mutate
frequently

None o the above

d. Surface protein genes in Neisseria gonorrhoeae mutate
frequently.

20

Which of the following statements is true?

The primary goal of a pathogen is to kill its host.

Evolution selects for the most virulent pathogens.

A successful pathogen doesn’t kill its host before it is transmitted.

A successful pathogen never kills its host

A successful pathogen doesn’t kill its host before it is transmitted.

21

Legionella uses C3b receptors to enter monocytes. This

prevents phagocytosis.

22

Chlamydia can prevent the formation of phagolysosomes and
therefore can

avoid being digested.

23

If the following are placed in the order of occurrence, which
would be the third step?
Diapedesis
Digestion
Formation of a phagosome
Formation of a phagolysosome
Margination

Formation of a phagolysosome

24

If the following are placed in the order of occurrence, which
would be the third step?
Activation of C5 through C9
Cell lysis
Antigen–antibody reaction
Activation of C3
Activation of C2 through C4

Activation of C3

25

A human host can prevent a pathogen from getting enough iron by

binding iron with transferrin.

26

A decrease in the production of C3 would result in

increased susceptibility to infection.

27

In 1884, Elie Metchnikoff observed blood cells collected around a
splinter inserted in a sea star embryo. This was the discovery of
a. blood cells.
b. sea stars.
c. phagocytosis.
d. immunity.
e. none of the above

phagocytosis.

28

Helicobacter pylori uses the enzyme urease to counteract a
chemical defense in the human organ in which it lives. This
chemical defense is

hydrochloric acid.

29

Which of the following statements about IFN-α (alpha interferon) is false

It is virus-specific.

30

Which of the following does not stimulate phagocytes?

histamine

31

The type of protection provided by the injection of diphtheria
toxoid.

artificially acquired active immunity

32

The type of protection provided by the injection of antirabies
serum.

artificially acquired passive immunity

33

The type of protection resulting from recovery from an infection.

naturally acquired active immunity

34

A newborn’s immunity to yellow fever.

naturally acquired passive immunity

35

Antibodies that protect the fetus and newborn.

IgA

36

The first antibodies synthesized; especially effective against
microorganisms.

IgM

37

Antibodies that are bound to mast cells and involved in
allergic reactions

IgE

38

Put the following in the correct sequence to elicit an antibody
response: (1) TH cell recognizes B cell; (2) APC contacts antigen;
(3) antigen fragment goes to surface of APC; (4) TH recognizes
antigen digest and MHC; (5) B cell proliferates.

2)APC contacts antigen,3)antigen fragment goes to surface of APC,4) TH recognizes antigen digest and MHC, 1)TH cell recognizes B cell, 5)B cell proliferates.

39

A kidney-transplant patient experienced a cytotoxic rejection
of his new kidney. Place the following in order for that rejection:
(1) apoptosis occurs; (2) CD8+ T cell becomes CTL; (3) granzymes
released; (4) MHC class I activates CD8+ T cell; (5) perforin
released.

4) MHC class I activates CD8+ T cell, 2) CD8+ T cell becomes CTL, 5) perforinreleased, 3) granzymes released, 1)apoptosis occurs

40

Patients with Chédiak-Higashi syndrome suffer from various
types of cancer. These patients are most likely lacking which
of the following:

NK cells

41

Patient’s serum, influenza virus, sheep red blood cells, and
anti-sheep red blood cells are mixed in a tube. What happens
if the patient has antibodies against influenza?

is hemagglutination-inhibition

42

Patient’s serum, Chlamydia, guinea pig complement, sheep red
blood cells, and anti-sheep red blood cells are mixed in a tube.
What happens if the patient has antibodies against Chlamydia?

d. no hemolysis

43

The examples in questions 1 and 2 are

indirect tests.

44

Which is the third step in a direct ELISA test?

substrate for the enzyme

45

Which item is from the patient in an indirect ELISA test?

anti-Brucella

46

In an immunodiffusion test, a strip of filter paper containing
diphtheria antitoxin is placed on a solid culture medium. Then
bacteria are streaked perpendicular to the filter paper. If the
bacteria are toxigenic,

a line of antigen–antibody precipitate will form.

47

Treatment given to a person bitten by a rabid bat.

rabies immune globulin

48

Test used to identify rabies virus in the brain of a dog.

direct fluorescent antibody

49

Test used to detect the presence of antibodies in a patient’s serum.

indirect fluorescent antibody

50

In an agglutination test, eight serial dilutions to determine
antibody titer were set up: Tube 1 contained a 1:2 dilution;
tube 2, a 1:4, and so on. If tube 5 is the last tube showing
agglutination, what is the antibody titer?

32

51

Desensitization to prevent an allergic response can be accomplished
by injecting small, repeated doses of?

the antigen (allergen).

52

What does pluripotent mean?

Ability of a stem cell to develop into many different cell types.

53

Cytotoxic autoimmunity differs from immune complex
autoimmunity in that cytotoxic reactions

do not involve complement.

54

Antibodies against HIV are ineffective for all of the following
reasons except

the fact that antibodies aren’t made against HIV.

55

Which of the following is not the cause of a natural immunodeficiency?

immunosuppressant drugs

56

Which antibodies will be found naturally in the serum of a
person with blood type A, Rh1?

anti B

57

Localized anaphylaxis

type I hypersensitivity

58

Allergic contact dermatitis.

type IV hypersensitivity

59

Due to immune complexes.

type III hypersensitivity

60

Reaction to an incompatible blood transfusion.

type II hypersensitivity

61

Which of the following pairs is mismatched?

antihelminthic—inhibition of cell wall synthesis

62

All of the following are modes of action of antiviral drugs except
inhibition of protein synthesis at 70S ribosomes.
inhibition of DNA synthesis.
inhibition of RNA synthesis.
inhibition of uncoating.
none of the above

inhibition of protein synthesis at 70S ribosomes.

63

Which of the following modes of action would not be fungicidal?
inhibition of peptidoglycan synthesis
inhibition of mitosis
injury to the plasma membrane
inhibition of nucleic acid synthesis
none of the above

inhibition of peptidoglycan synthesis

64

An antimicrobial agent should meet all of the following criteria
EXCEPT ?

the production of hypersensitivities.

65

The most selective antimicrobial activity would be exhibited by a
drug that?

inhibits cell wall synthesis.

66

Antibiotics that inhibit translation have side effects?

at the 70S ribosomes in eukaryotic cells.

67

Which of the following will NOT affect eukaryotic cells?

inhibition of the mitotic spindle, binding with sterols, binding to 80S ribosomes, binding to DNA, All of the above will affect them.

68

Cell membrane damage causes death because?

cell contents leak out.

69

A drug that intercalates into DNA has the following effects. Which
one leads to the others?

It interferes with DNA replication.

70

Chloramphenicol binds to the 50S portion of a ribosome, which
will interfere with?

translation in prokaryotic cells.