Virulence may be measured experimentally at the host level by the ________, which measures the number of pathogens that kills 50% of an experimental group of hosts within a specified amount of time.
Fill in the blank(s) with the appropriate word(s).
lethal dose 50
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What method was used to inoculate the plate shown here?
CDC
A. Swab plate B. Pour plate C. Streak plate D. Spread plate
Individuals entering the room of a patient with Legionnaires' disease should wear a mask to prevent acquiring the disease from exposure to the patient.
Answer the following statement true (T) or false (F)
Four of the following characterize a population in genetic equilibrium. Which one is the exception?
a. large population size b. no mutations c. differential reproduction d. absence of gene flow e. random mating
If you were given a bacterial strain with a mutation in the promoter region of the trp operon the most likely effect would be
A. lack of expression of just the first gene in the operon. B. interference with RNA polymerase binding. C. enabling the trp operon to be expressed in the absence of tryptophan. D. derepression of the trp operon. E. to block the repressor from binding.