The evolutionary force of tends to increase genetic variation within a population but decrease genetic variation between populations, while the evolutionary force of tends to decrease genetic variation within a population but increase genetic variation among populations.

The evolutionary force of MIGRATION tends to increase genetic variation within a population but decrease genetic variation between populations, while the evolutionary force of GENETIC DRIFT tends to decrease genetic variation within a population but increase genetic variation among populations.

Explanation:

Migration is the movement of individuals from one population to another and results in a transfer of alleles from one population to another. When the immigrated individuals interbreed, they add new alleles to the gene pool of the recipient population. Therefore, migration increases the genetic variations within the population. When sufficient alleles flow from one population to another by migration, they become more similar genetically.  

Genetic drift refers to random changes in the allele frequencies of a small population by any chance event. Genetic drift may eliminate an allele of a gene irrespective of the adaptive nature of another allele. Therefore, genetic drift reduces the genetic variations within a population but tends to increase the genetic differences among different populations.

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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a few examples of ethical concerns involving genetically engineering of humans include

-privacy of genetically tested people

- potential side effects

-long term effects