<span>Food molecules like lipids, proteins and polysaccharides are broken down enzymatically via digestion process, which occurs in our intestine cells (digestive system). Those large polymeric molecules are broken down into their monomer subunits—proteins into amino acids, polysaccharides into sugars, and fats into fatty acids and glycerol. Formed small organic molecules are now ready for the oxidation (a process that produces ATP and consumes O2) which occurs partly in the cytosol and in the mitochondrion. Oxidation processes include glycolysis and citric acid cycle which are differently required in different tissues. Nervous system (nerve cells) rely almost entirely on a constant supply of <span>glucose<span> from the bloodstream. In contrast, liver cells supply glucose to actively contracting muscle system which needs a lot of ATP energy.</span></span></span>
Birds and butterflies don't have a common ancestor because one is a member of a insect and the other is well a bird. They both have different body structure. One has bones and the other has an exoskeleton. hope this helps
There would be more evidence spread out through space to be noticed by scientists and it seems like a stretch to go as far back as 4 billion years ago.
(I mean really? That much before the DINOSOURS died? I don't think so)
