When a bond forms between units of a macromolecule a water molecule is lost what is this process called

The correct answer will be dehydration synthesis.

Explanation:

Dehydration reaction is the formation of larger molecules by the removal or loss of water molecule. It is a subset of condensation reactions in which two functional groups combine to form a covalent bond releasing water molecule as by-product.

This reaction is found in synthesis of many biological molecules like carbohydrates, proteins, triglycerides and nucleotides. as well as in industries like the formation of the alkenes which are used as base chemicals are formed by the dehydration of alcohols.

Thus, dehydration synthesis is the correct answer.

a "theory" a suggestion that is not 100 % accurate, or a figure. some people say its a theory because they of all the passed theory's about one subject. it depends sometimes theory might be accurate and sometimes they are.

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.