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beigeeel743Lv1

28 Sep 2019

Koch's postulates were developed to identify specific microbial causes of disease. Is the following statement regarding Koch's postulates True or False?

One type of microbe for which it might be difficult to demonstrate Koch's postulates is viruses, because these cannot be "isolated and grown in pure culture".

What does it mean to be isolated and grown in pure culture?

Is this question true or False?

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Hubert KochLv2

28 Sep 2019

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QUESTION 7

Which statement most accurately describes the evolutionaryrelationships among the three domains?

		Bacteria and Archaea diverged from a common ancestor morerecently than they diverged from their common ancestor withEukarya
		Bacteria and Eukarya diverged from a common ancestor morerecently than they diverged from their common ancestor withArchaea
		Eukarya and Archaea diverged from a common ancestor morerecently than they diverged from their common ancestor withBacteria
		All three domains diverged from a common ancestor at the sametime.

10 points

QUESTION 8

Bird influenza is an emerging disease. If you were given thetask of using Koch's postulates of finding the pathogen causingbird flu, what sequence of procedures should you use?

		(1) Inoculate a healthy bird with the suspected pathogen to seewhether it becomes sick, (2) compare symptoms of that bird withthose of a bird known to have the disease, (3) isolate the pathogenfrom both birds in pure culture and stain them to see whether theyare both Gram-positive, and (4) make a vaccine from the pureculture of one bird and inject it into another to see if itrecovers.
		1) Take blood samples from a sick bird, (2) isolate the pathogenin pure culture, (3) treat the bird for the disease and when itrecovers take a second blood sample, and (4) test the blood tocheck whether it no longer contains the pathogen.
		1) Inject a bird with the suspected pathogen, (2) inject anotherbird with a control that doesn't contain the suspected pathogen,(3) repeat with more birds, and (4) plate out samples of blood fromboth kinds of birds to see if you can isolate the pathogen in pureculture.
		(1) Check whether the suspected pathogen is present in sickbirds, then (2) isolate the pathogen from an infected bird and growit in pure culture, (3) inoculate cells from pure culture into ahealthy bird to see whether it causes the disease, and (4) attemptto isolate the suspected pathogen from the inoculated bird.

10 points

QUESTION 9

The evolution of organisms that use oxygen in their respirationwas possible only because of the action of a group of bacteria thatproduced oxygen and changed the Earth's atmosphere from an anoxicone to one rich in oxygen. That group of bacteria was:

		cyanobacteria
		spirochaetes
		proteobacteria
		Staphylococcus

10 points

QUESTION 10

Microcystis aeruginosa is a species of cyanobacteria.What CANNOT be true of this species?

		It synthesizes organic molecules.
		It is an obligate anaerobe
		Its cells contain an extensive thylakoid
		It uses ammonia to produce proteins.

1. Select which of the following are mechanisms used by pathogens to avoid host defenses and to successfully colonize the host.

A. Producing siderphores to obtain iron from the host for growth

B. producing adhesins for damaging host cells

C. Avoiding IgA proteases for avoiding secretory IgA

D. Avoiding secretory IgA by rapid turnover of pili

E. Producing toxic substances to suppress host responses

2. People considered obese have a different normal flora in the gastrointestinal tract compared to people who are considered lean.

A. true

B. false

3. Which of the following is NOT a mechanism used by pathogens for avoiding or surviving phagocytosis?

A. Killing macrophages and neutrophils

B. Colonizing the phagocyte

C. inhibiting opsonization

D. Inhibiting phagocte chemotaxis

E. these are all methods of avoiding or surviving phagocytosis

4.Which of the following immune responses is best suited to prevent a virus from infecting a cell?

A. complement cascade

B. inflammation

C. Virus-specific antibodies

D. Fever

E. phagocytic cells

5. Which of the following is NOT a method used by pathogens for penetrating skin or mucous membranes?

A. Injection of effector proteins that induce endocytosis

B. Exploiting antigen-sampling processes

C. these are all mechanisms for penetrating skin or mucous membranes

D. Exploiting an injury

E. Production of endotoxin

6. Antibodies, which are produced as part of the adaptive immune response, can sometimes be damaging rather than beneficial. People suffering from an autoimmune disease called antiphospholipid antibody syndrome (APS) make antibodies that bind to phospholipids. Some of the signs and symptoms affected individuals experience are blood clots, stroke, heart attack, and kidney damage. What is the likely cause of these symptoms?

A. the anti-phospholipid antibodies cuse immune complexes that lodge in the affected organs

B. The person fails to make protective antibodies

C. The anti-phospholipid antibodies weaken certain organs that contain fat

D. the person makes antibodies that bind inappropriately to bacterial capsules, preventing phagocytosis of these cells

E. Cell damage caused by binding of these antibodies initates inappropriate coagulation events which inferfere with blood flow in affected organs.

7. Only Gram-positive bacteria produce exotoxins

A. true

B. False

8. Which of the following members of the normal microbiota inhibit the growth of Candida albicans?

A. Lactobacilus species

B. Staphylococci species

C. E. coli

D. Neisseria species

E. Propionibacterium species

9. Would an antibody response against the B subunit of an A-B toxin protect against the effects of the toxin?

A. yes. if antibodies bind to the B protion, the toxin can no longer bind to target cells and will thus not affect those cells

B. No, even if antibodies bindto the B portion of the toxin, it is the A portion that actually causes damage to the cell

C. This question cannot be answer. The immune system does not mount a strong response against proteins, so this situation is unlikely to occur.

D. Yes, if antibodies bind to the B protein, that portion of the toxin does not become activated, and thus does not damage the host cell

E. No, even if antiibodies bind to the B portion of the toxin, the toxin is still taken into the host cell by phagocytosis, damaging that cell

10. Please select the correct definition of balanced pathogenicity.

A. A host-parasite relationship in which the parasite persists in the host, causing maximal harm. The pathogen becomes more virulent while the host becomes increasingly susceptible.

B. A mechanism that allows bacteria to transfer gene products directly into host cells, inducing changes such as altering the cell's cytoskeleton structure

C. A generated balance in the microbiome that may be caused by taking antimicrobial medication. it generally helps the host maintain optimal health

D. A situation in which an abnormally high number of T-helper cells are stimulated, causing a massive release of cytokines.

E. A host-parasite relationship in which the parasite persists in the host while causing minimal harm. The pathogen becomes less virulent while the host becomes less susceptible

11. Bacteria may survive phagocytosis by

A. preventing encounters with phagocytes AND preventing fusion of two pathogosomes

B. avoiding recognition and attachment of lymphocytes AND lysinf the phagosomes

C. preventing fusion of the lysosome with the phagosome AND mimicking host molecules

D. lysing the phagosome AND mimicking host molecules

E. preventing fusion of the lysosome with the phagosome AND lysing the phagosome

12. In two of Koch's postulates (#2 and #3), a pure culture of the organism is required. Which of the following would NOT be a possible consequence of using a contaminated culture?

A. these would all be consequences of using contaminated cultures

B. Even though there's a contaminating microbe present, as long as the original suspect microbe is also present, the disease should still manifest in test animals and the organism should still be recoverable from test animals. As such, there's really no consequence to using a contaminated culture

C. The problem is that one microbe may be toxic to other. It may have killed all of your suspect microbe in the culture. Therefore, you can't be sure that you're infecting your test animals with the microbe you suspect is causing the illness, or if it's only the sec. microbe.

D. you can't necessarily attribute the illness directly to the microbe in question; it may in fact be caused by the contaminating microbe

E. There's the possibility that the test animal might be acutely susceptible to the contaminating microbe, but completely resistant to the microbe you suspect causes the illness of interest. As such, when you introduce it into the test animal, it could confuse your final results.

1) What is the most efficient and cost-effective way to control infectious diseases? A) variolation C) passive immunotherapy using immunoglobulins B) active immunization by vaccination D) immune testing E) autoimmunization 2) Variolation was first used _______ A) to immunize the Chinese against smallpox. B) to protect individuals against the plague during the Middle Ages. C) to spread smallpox throughout the Native American populations. D) to treat individuals exposed to hepatitis. E) for research purposes in the 20th century. 3) Almost a century after Edward Jenner introduced successful vaccination, Louis Pasteur developed vaccine(s) against A) anthrax. B) human cholera. C) rabies. D) influenza. E) both anthrax and rabies. 4) Pathogens may be attenuated for use in vaccines by ______ A) raising the pathogen for several generations in tissue culture cells. B) genetic manipulation. C) treatment with formaldehyde. D) genetic manipulation coupled with treatment with formaldehyde. E) genetic manipulation and/or raising the pathogen for several generations in tissue culture cells. 5) Which of the following statements regarding an inactivated vaccine is FALSE? A) It can be produced with deactivated whole microorganisms. B) It can be produced from antigenic fragments of a pathogen. C) It is safer than an attenuated vaccine. D) It is made from mutated forms of the pathogen. E) It is made from pathogens that cannot replicate. 6) Which of the following substances is commonly used to inactivate microbes before using them for vaccination? A) formaldehyde B) aluminum C) mineral oil D) saponin E) aluminum phosphate 7) What type of vaccine is the hepatitis B vaccine? A) inactivated whole pathogen B) attenuated vaccine C) toxoid vaccine D) a recombinant vaccine composed of a single antigen of the hepatitis virus E) a vaccine produced by treating the virus with formaldehyde 8) An infectious disease researcher isolates the pathogen responsible for an emerging disease. The microbe is grown in the lab for many generations. A preparation of the laboratory-grown microbe is treated with ionizing radiation and then tested for its potential as a vaccine. What type of vaccine is this? A) attenuated B) subunit C) combination D) toxoid E) inactivated whole 9) OPV, the attenuated oral poliovirus vaccine, is no longer administered in the U.S.A. because it A) is very toxic. B) does not provide good immunity. C) can revert to wild-type virulence. D) can be spread to contacts. E) can be spread to contacts and can revert to wild-type virulence. 10) Hybridomas are factories for antibodies and are produced by _____ A) combining two virus-infected cells. B) fusing plasma cells with myeloma cells. C) repeated culture of a pathogen until it loses its virulence. D) combining a viral infected cell with a bacterial infected cell. E) combining two bacterial infected cells. 11) The study and diagnosis of antigen-antibody interactions in the blood is known as _____ A) immunology. B) hematology. C) serology. D) cytology. E) histology. 12) Which type of antibody assay is represented in this figure? A) an indirect ELISA C) an indirect immunofluorescence assay B) a direct ELISA D) a western blot E) an immunodiffusion assay 13) Titration is a serological procedure that A) identifies the causative microbe of an infectious disease. B) determines the amount of an antibody in the blood. C) must be done before the western blot test to diagnose HIV. D) is used for blood grouping. E) has been replaced by genetic engineering in isolating the antigen of a pathogen. 14) A woman uses a home pregnancy test kit that tests for hCG hormone in urine. She knows this is a type of antibody assay from the kit brochure. Antibodies reacting with the hormone produce two lines on the test strip. What specific type of antibody assay does this represent? A) a direct immunofluoresence test C) an immunochromatographic assay B) a complement fixation test D) an ELISA E) a neutralization assay 15) The complement fixation test uses red blood cells as the target for complement activation. Test serum containing antibodies is combined with a known amount of antigen in a tube, and then the RBCs and antibodies against the RBCs are added. A positive result for the complement fixation test would be A) a line of precipitate near the bottom of the tube. C) loss of color in the tube. B) a cloudy solution in the tube. D) a fluorescent precipitate. E) a solution that is clear due to precipitation of RBCs.

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