Combine the given two facts to write a concluding fact. Note that there should be some parts of the first and second facts that are not mentioned in this conclusion fact. Your combined fact should be the result of a chain between the two facts. Chains form when two facts connect together to produce a concluding fact. An example of a chain is: "pesticides cause pollution" (fact1) + "pollution can harm animals" (fact2) → "pesticides can harm animals" (conclusion fact). Parts of the concluding fact overlap with the first and the second fact. To construct such a  concluding fact, a useful way is to borrow the subject from one fact and the ending conclusions from another fact.

Fact 1: Chemical bonds form when substances react with one another. 
Fact 2: All substances are composed of molecules.
Chemical bonds form when molecules react with one another.

Fact 1: Evolution occurs by a process called natural selection. 
Fact 2: Adaptation and natural selection are discussed.
Evolution occurs by a process of adaptation.

Fact 1: Food consists of organic molecules that store energy in their chemical bonds. 
Fact 2: Chemical bonds are electrical in nature.

Food consists of organic molecules that store electrical energy.