All of the following circumstances, except can produce new combinations of genetic traits in sperm and eggs that are different from the parents.
a) errors during meiosis
b) errors during mitosis
c) crossing over during meiosis
d) mutations due to exposure to chemicals

The correct answer is B.) errors during mitosis

cramming before a final is bad because it makes a student's stress level higher. students who embrace cramming to get through a final exam week find themselves struggling to perform consistently, once the brain adjusts to prolonged sleep deprivation.

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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