✔ 最佳答案
the ideal of digestion is to increase the surface area by reducing the size. When the "bit" become so small, where the molecular size become less then 1000, our body can absorb it by diffusion.
so starch become simple sugar with molecular size approx 100
so protein become amino acid with molecular size approx 100
and fat become fatty acid, or phospholipid with molecular size approx 100-1000...
regarding the nucleic acid, if i remember correctly, ACTG have small molecular weight, about 100-400? when the DNA is break down to ACTG, by some protease enzyme, it will absorbe accordingly.
regarding phospholipid, well, we break down the fat to fatty acid in the form of phospholipid, it is then absorb by mean MYCELL in the small intestine.
I don't think we absorb phosphorus, but phosphoric acid...