This question is not clear, but I think I understand what you are asking. The difference between alleles of a gene is that some alleles may be dominant or recessive. If one gene has more dominant alleles than another, than it will be more visible.
Internal means its on the inside
external means its on the outside
so an internal regulator is when the proteins respond to events on the inside of a cell
and an external regulator is when the proteins respond to events outside the cell
All of the above should be the answer since mutation is is a change of the DNA sequence that are resulted from DNA copying mistakes made during cell Division, or even exposure to ionizing radiation
