Why is this technique Punnett squares used to calculate the probability of genotypes and phenotypes of one child. In other words, why is it inappropriate to say "Two out of four of their children will have brown hair? Please help meee

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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answer///unconditioned stimulus;