What factors led to the commercial extinction of northern cod?

Regulations safeguarding cod stocks did not evolve alongside the world's ability to harvest fish, and governments or international bodies sometimes assigned quotas based on economic factors rather than ecological ones. Although conservation became an increasing concern after the 1960s, officials consistently overestimated the size of cod stocks and, as a result, also overestimated the amount of cod fishers could harvest at sustainable levels.

the answer that best describes the relative refractory period in the neuron is the resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.

the refractory period is the time during which another stimulus given to the neuron will not lead to a second potential. thus, because na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials.  

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i'd say that the moon rock is about 2.2 billion years old.