The Miller and Urey experiment (or Urey–Miller experiment) was an experiment that made organic compounds out of inorganic ones by applying a form of energy. Paraphrase - what was the purpose of the Miller-Urey experiment (what were they trying to prove)?

The goal of the Miller-Urey experiment was to test the idea that through basic, natural chemical reactions, the complex molecules of life (in this case, amino acids) may have emerged on our young world. The experiment was a success in generating during the simulation amino acids , the building blocks of life.  

They were trying to prove that the formation of life was preceded by chemical evolution.

Explanation:             MILLER-UREY EXPERIMENT

    The Miller-Urey experiment (or Miller experiment) was a chemical experiment that simulated the conditions thought to be present on early Earth at the time (1952) and under those conditions tested the chemical origin of life. At that time, the experiment sponsored Alexander Oparin's and J. B. S. Haldane 's belief that putative conditions favored chemical reactions on the primitive Earth that synthesized more complex organic compounds from simpler inorganic precursors. It was conducted in 1952 by Stanley Miller, supervised at the University of Chicago by Harold Urey, and published the following year as the classic experiment investigating abiogenesis.

Water (H2O), methane ( CH4), ammonia ( NH3) and hydrogen ( H2) were utilized in the experiment. Within a sterile 5-liter glass flask linked to a 500 ml flask half-full of water, the chemicals were all sealed. To cause evaporation, the water in the smaller flask was heated and the water vapour was allowed to reach the larger flask. In order to simulate lightning in the water vapor and gaseous mixture, continuous electric sparks were shot between the electrodes and then the simulated atmosphere was cooled again so that the water condensed and trickled into a U-shaped trap at the bottom of the apparatus.

The solution gathered at the trap had turned pink after a day, and the solution was deep red and turbid after a week of continuous operation. The boiling flask was then removed and mercuric chloride was applied to avoid microbial contamination. By adding barium hydroxide and sulfuric acid, the reaction was discontinued and evaporated to eliminate impurities. Using paper chromatography, Miller detected five amino acids found in the solution: glycine, α-alanine and β-alanine were positively identified, while aspartic acid and α-aminobutyric acid (AABA) were less certain, due to the spots being faint.

Therefore, Miller's experiment was trying to prove the formation of diverse organic molecules from inorganic molecules.

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 -