What is the first 25 cm of the small intestine called?

Its called the duodenum.

hope this helps you

This is what i found on google“ the monomers combine with each other via covalent bonds to form larger molecules known as polymers. in doing so, monomers release water molecules as byproducts. this type of reaction is known as dehydration synthesis, which means “to put together while losing water. in the process, a water molecule is formed.” i hope this you

That would be a working theory.