Treponema pallidum is the bacterium that causes syphilis. The gram-negative spirochete has never been cultured on bacteriological media. Select the statement that most accurately describes this disease-causing microbe.
A. Koch's postulates cannot be fulfilled for this disease.
B. There is no satisfactory way to identify the disease without being able to grow it.
C. There is no way to perform an epidemiological study on this disease.
D. Because the bacterium cannot be grown, there is no way to characterize the organism as to staining features, biochemical test reactions, molecular testing, etc.
Answer: A
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Which of the following characteristics distinguished T cells from B cells?
A. B cells produce immunoglobulin while T cells do not. B. B cells originate in the bone marrow while T cells do not. C. B cells form memory cells while T cells do not. D. B cells are lymphocytes while T cells are not.
If a drug interferes with the activities of transfer RNA, which one of the following is likely to occur?
A. DNA will not be able to make copies of itself. B. Proteins will not be produced. C. Mutations will occur to the DNA. D. Messenger RNA will not be manufactured.
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.
In which phase of the bacterial cell cycle do the cells grow most quickly?
A) log B) stationary C) fluctuation D) adaptation E) lag