Identify the key feature of the action potential that ensures it will travel only one direction.
A. the activation state of the voltage-gated Na+ channel
B. the inactivation state of the voltage-gated Na+ channel
C. the activation state of the voltage-gated K+ channel
D. the inactivation state of the voltage-gated K+ channel
E. the temporary cessation in activity of the Na+/K+ pump
B. the inactivation state of the voltage-gated Na+ channel
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Which of the following statements about patterns of energy use among countries is false?
A. Individuals in larger countries use more energy than individuals in smaller countries. B. Individuals in high-latitude countries use more energy than individuals in equatorial countries in part because of the need to heat buildings. C. Countries where individuals travel more frequently have higher levels of energy use than countries where individuals travel less frequently. D. Individuals in countries with higher standards of living use more energy than countries with lower standards of living. E. Energy use is distributed unevenly among countries.
Most intertidal chitons are considered
a. grazers. b. predators. c. scavengers. d. filter feeders. e. infauna.
Which of the following does NOT describe bacterial flagella?
a. smaller and simpler than eukaryotic flagella b. consist of a helical fiber of protein c. found in all motile bacteria d. powered by a gradient of hydrogen ions e. lacks microtubules.
What must occur before a newly made polypeptide is secreted from a cell?
A) It must be translated by a ribosome that remains free within the cytosol. B) Its signal sequence must target it to the ER, after which it goes to the Golgi. C) Its signal sequence must be cleaved off before the polypeptide can enter the ER. D) Its signal sequence must target it to the plasma membrane, where it causes exocytosis.