What is made of a single long molecule dna a. allele b. nucleus c. chromosome d. protein

The correct answer is option C, Chromosome

Explanation:

The structure of chromosome consists of DNA forming a tightly coiled structure around associated proteins mainly histone. The DNA looks like thread like structures which are packaged to form chromosome. So the basic structure of all the chromosomes consists of a DNA molecule and a protein. The double stranded DNA loops around the histones twice to form nucleosome which are considered as building block of chromatin packaging

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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b) the inside picture would look at a very high temperature in a very low ph