Charles Darwin:
a. inferred the patterns of common ancestry without a mechanistic understanding of genes and heredity.
b. developed a hypothesis about past events that later became testable.
c. argued that humans descended from another primate species and once walked on all fours.
d. All of the above.
B
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When species of a single large population slowly evolves over generations into a new species, this an example of
A. adogenesis. B. cladogenesis. C. anagenesis. D. monospeciation. E. punctuated equilibrium.
Cytotoxic T cells destroy cancerous cells by
A. forming the membrane attack complex. B. releasing vesicles containing perforin. C. activating natural killer cells. D. opsonization. E. secreting cytokines.
J. H. Connell proposed that competition occurred between barnacle species; he based that on:
a. the observed distribution of the species and environmental measurements. b. laboratory test he had concluded. c. a conversation with other scientists. d. the observation that they were in the rocky intertidal. e. laboratory observations of their fighting behavior.
Ion concentration differences produce an action potential creating a signal. The difference between a weak signal and an intense signal is
A. weak stimuli only open sodium gates, strong signal also open potassium gates. B. the frequency at which an axon fires. C. the action potential is graduated and a weak signal causes a small change in polarity. D. a strong signal does not allow repolarization but sends a constant flow of ions. E. All of the choices are correct.