The several hundred species of picture-winged fruit flies of the Hawaiian Islands are genetically very similar, yet they all differ markedly from their ancestral population in Asia. This is probably accounted for by
A. disruptive selection.
B. the founder effect.
C. directional selection.
D. gene flow.
E. sexual selection.
Answer: B
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Transcriptional regulation in eukaryotic cells requires the coordinated action of many proteins that interact with one another and with DNA sequences near the gene
A. true B. false
An action potential is propagated down an unmyelinated neuronal plasma membrane because it stimulates voltagegated
____ channels adjacent to it. (Choose the most accurate answer.)
a. Na+ b. Ca2+ c. K+ d. Na+ and Ca2+ e. K+ and Ca2+
Which of the following is a common reason for hybrid infertility?
a. They express mechanical incompatibility. b. They are found to be ecologically isolated. c. A common reason for hybrid infertility is the failure of chromosomes to pair properly during meiosis. d. They fail to reach sexual maturity.
Which statement about parasitism is true?
a) The host is generally smaller than the parasite. b) There are examples of parasites in every kingdom of life. c) Parasites are always severe and kill the host. d) All parasites will remain attached to their host for the entire life span of the host. e) All parasites require a single host for their life cycle.