20 g O2 x 1 mol O2/32 g O = 0.625 mol O2
I believe its called mitosis. Mitosis is a type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus, typical of ordinary tissue growth. Hope this helps:)
The DNA is identical because all of your cells came from that one cell through mitosis which gives and exact copy of the DNA. All body cells got the complete "instruction manual" for the body, but only uses the proteins needed.
