People who wash their hands frequently during cold season typically have fewer colds than those who do not. This observation suggests cold viruses can be transmitted by
A) fomites.
B) mechanical vectors.
C) biologicalvectors. transmission.
D) direct contact.
E) both direct contact and fomites.
E
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Sickle-cell anemia is an example of what type of mutation?
A. silent B. missense C. nonsense D. frameshift E. base pair deletion
Plant activities that follow a biological clock so that they are based on cycles of about 24 hours are ____
a. gravitropisms
b. photoperiodisms c. thigmotropisms d. circadian rhythms e. phototropisms
The structure labeled "A" in the figure is a(n)
a. club-shaped reproductive cell. b. zygote. c. ascus. d. gill from the underside of a mushroom. e. spore sac.
The relatively high percentage of individuals in West Africa who are heterozygous for the sickle cell trait is an
example of _____. a. natural selection b. genetic drift c. spontaneous mutational spread d. heterozygote disadvantage e. the founder effect