Why is gene regulation necessary in the development of multicellular organisms? use a specific example to support your argument.

Gene regulation refers to the regulation of expression of a particular gene in a cell that is, it increases or decreases the expression of a particular set of genes in a particular cell.  

In multicellular organisms, gene regulation plays a crucial role in cell differentiation and maturation.  

It enables the formation of different types of cells or tissues from a single type of stem cells that is, it enables the formation of a multicellular organism from a single cell zygote.

For example, muscle cells, nerve cell, skin cell et cetera all arise from a single-celled zygote. It is possible due to highly regulated gene expression.

All cells contain the same genetic information (DNA) but different sets of genes are expressed in different specialized cells.

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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i'd say that the moon rock is about 2.2 billion years old.