To deliver appropriate oxygen for respiration and cell mitosis.
It actually refers to the genetic traits, which change during time, because if you stop to think about it, surely, dogs 400 years ago were not the same as the dogs we see today since they have had changes in their genetic sequences, which adapted them to live better and even new species have appeared (or simply have been "made" which even so, depends on a genetic change).
Hope it helped,
BioTeacher101
Well the energy is stored in NADH and FADH2 during the krebs cycle and convert it to chemical bond energy in the form of ATP. In Eukaryotas, this reaction takes place on the inner mitochondrial membrane.
