Copper in soil is usually toxic to plants, but some plants that grow near copper mines evolve copper tolerance. when copper-tolerant plants are grown in copper-free soil, they are outcompeted by the non-tolerant genotype. which of the following principles does this scenario exemplify?
a.
the evolution of tolerance to copper resulted in a dependence on copper
b.
evolution always maximizes the improvement or progress of a species
c.
evolutionary changes can be advantageous under some environmental conditions but disadvantageous under others
d.
resistant phenotypes always out-compete non-resistant phenotypes

C. Evolutionary changes can be advantageous under some environmental conditions but disadvantageous under others

Explanation:

Evolution means to change something to survive, but that is under specific context. If we change the context, maybe that evolution is not advantegerous on the new scenario or context.

In this case, the plant evolve to survive copper in soli. If the soil has no more copper, that evolution is no longer needed.

what are the choices?

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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