Explain pesticides resistance. how does it accur? why is it a concern?

Pesticide resistance at a population level, as opposed to just a few individual pests within a species, can occur after repeated exposure to a single type of pesticide. ... When a resistant population occurs, the pesticide is no longer useful for managing that specific pest and other management options must be sought out.

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.  

read more on -

the answer would be..

b. sucking