Describe how the effects of directional selection can be offset by gene flow.
What will be an ideal response?
If directional selection eliminates one allele, but new migrants replace it, the frequencies may stay the same.
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An important functional role of the endocrine system is to
a. provide mechanisms for rapid responses to changes in the body. b. allow for mechanisms to control gene action. c. inhibit nervous system action on muscles and glands. d. maintain a constant, yet dynamic internal fluid environment. e. fight infection.
If an injection to the mouse contains live R strain Streptococcus pneumonia, _____
a. the mouse will die b. live S strain will be detected in the mouse's blood c. the mouse will live d. no live R strain will be detected in the mouse's blood e. the live R strain bacteria will develop pathogenicity
The sequence of eras beginning with the earliest era and processing forward to the most recent era in the geologic time scale is
A. Archean - Mesozoic - Cenozoic. B. Cenozoic - Archean - Mesozoic. C. Archean - Paleozoic - Proterozoic. D. Mesozoic - Cenozoic - Paleozoic. E. Paleozoic - Mesozoic - Cenozoic.
Syphilis and Lyme disease and strikingly similar in which of the following aspects?
A. Their modes of transmission are similar B. Both diseases display three, distinct phases C. Both causative agents can be cultured D. The diseases show cross-immunity