Almost all of the products of the digestion are absorbed through the wall of the small intestine

This statement is true. The small intestine facilitates absorption of most of digestion products. Approximately 90% absorption takes place here. The following are absorbed:

Water

Fats

Amino acids

Glucose

Water soluble vitamins including C and B12

Fat soluble vitamins including A,D, E and K

Some minerals including Sodium, Potassium, Calcium, Magnesium and iron

Bile (a thick alkaline fluid secreted by the liver  and stored in the gall bladder)

In the large intestine, the remainder of sodium and potassium that were not absorbed in the small intestine are absorbed as well as water, acids and bases.

identify the dna change shown in the diagram and explain how that change can result in the increased genetic diversity often seen among siblings.