Which of the following circumstances is/are of concern in an attempt to fulfill Koch's postulates?

a. Infected animals do not show the same symptoms as infected humans.
b. The suspected pathogen is present in healthy humans.
c. An axenic (or "pure") culture cannot be obtained.
d. All of the above are of concern.


Answer: D

Biology & Microbiology

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A. true B. false

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The average annual temperature among geographic regions is plotted on the x-axis of a graph and the spiciness of local food in that region is plotted on the y-axis

If the hotness of local food increases as the average annual temperature increases, then what can be concluded? A) The spiciness of local food does not correlate with the regional average annual temperature. B) Food is spicy in warm climates because the warm temperatures make local foods more spicy. C) The relationship between the two variables shows causation but is not correlation. D) Spiciness of food and annual average temperature are correlated, but causation is not implied.

Biology & Microbiology

What is the smallest number of ultracentrifugation steps needed to separate nuclei from ribosomes in a cellular lysate?

a. Two b. One c. Four d. Seven

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Which biological process determines the probability that particular alleles will be found inany given gamete?

A. mutation B. meiosis C. cell cycle D. protein synthesis

Biology & Microbiology