What event immediately precedes the nerve firing an action potential?
A. Depolarization is initiated.
B. The threshold potential is reached.
C. Volted-gated Na+ channels close.
D. Volted-gated K+ channels open.
E. The membrane becomes hyperpolarized.
B
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Four of the five terms involve fungus and food. Select the exception:
a. mold, blue cheese b. fermentation, soy sauce c. yeast, bread d. truffles, host trees e. soil fungus, penicillin
The semilunar valves are located between the
a. left and right atria. b. left ventricle and left atrium. c. both ventricles and the arteries that lead away from them. d. right atrium and right ventricle. e. left and right ventricles.
Which of the following processes does not generate genetic variation during sexual reproduction?
A) Crossing over B) Independent assortment C) Random fertilization D) All of the processes above generate genetic variation
Which statement is true about speciation on island archipelagos?
A. Species clusters are less common. B. Speciation by polyploidy is most common. C. Ecological competition may cause new species to go extinct slowing speciation. D. Speciation is slow because it depends on emigration from the mainland. E. Most speciation occurs allopatrically.