For each of the following, tell whether it is rare or common in the fossil record, and why.
1. marine-dwelling organisms
2. desert-dwelling organisms
3. flowers
4. recent organisms

1. The fossil records of the marine dwelling organisms are relatively common. As the aquatic species die their body falls to the bottom of the sea. These dead bodies get buried in the sediments in comparison to the terrestrial species. Due to this the decomposition process of the marine species gets slow down, and thus, are found commonly in fossil records.  

2. The fossil records of desert-dwelling species are relatively rare. As the body of the dead desert animal remains upon the sand until it gets buried naturally, which is a time-consuming procedure. This time is enough for the microorganisms to act as decomposers. Thus, fossil formation becomes rare.  

3. The fossil records of flowers are relatively common. It is due to the fact that the flowers comprise pollen grains and the pollen grains exhibit hard outer covering formed of two layers.  

4. The fossil records of the recent organisms are found commonly. The fossils of species that were found millions of years ago are more likely to be found in the rocks. As the species get buried between the rocks, therefore, the oxygen is very negligible or low in order to decompose the body of the species. The fossils present in the rocks get eroded with time or gets transformed into other forms due to heat or pressure.  

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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