In the early 1900s, cities such as Philadelphia reduced the incidence of typhoid fever by
A) isolating human carriers.
B) using tertiary water treatment systems.
C) filtering municipal drinking water through sand-bed filters.
D) requiring residents to boil drinking water.
E) mass vaccination of residents.
C
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"Flesh-eating" Streptococcus pyogenes is considered a newly emerging disease
Indicate whether this statement is TRUE or FALSE.
Which of the following agents is a known cause of
mutations? a. nonionizing radiation b. ionizing radiation c. transposons d. chemicals in cigarette smoke e. all of these
Which of the following observations supports the "good genes" hypothesis to explain male/male competition and female choice?
A. The color and quality of male sage grouse air sacs, used in courtship displays, are extremely sensitive to parasitic infections B. Ring-tailed lemurs mate only during the autumn breeding season, and females are not receptive to males at other times of the year C. Female widowbirds prefer males with the longest tails, but males with longer tails are more susceptible to predation D. Human males with symmetrical faces are considered more attractive than those with asymmetrical faces
Which molecule combines with proteins to form both the large and small ribosomal subunits?
A. rRNA B. RNA polymerase C. tRNA D. miRNA E. DNA