He process of turning molecules that are ingested into forms that are compatible with the organism is

I believe this process is known as Assimilation. In this process nutrients are absorbed into the body after digestion in the intestine and its transformation in biological tissues and fluids. Assimilation is different from absorption as absorption involves the process of moving food from the digestive system into the blood system for the transportation to all body parts, while assimilation is the uptake of nutrients into cells and tissues and consequent building up into mores complex substances.