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: Producers are organisms that produce food for themselves and other organisms. 
Fact 2: Autotrophs are organisms that can make their own food.
An autotroph is a producer that can produce food for itself.

Fact 1: Mammals generate heat mainly by keeping their metabolic rate high. 
Fact 2: Humans use food to generate body heat.
food keeps mammals' metabolic rates high.

Fact 1: freezing means changing from a liquid into a solid by reducing heat energy. 
Fact 2: Frostbite is the freezing of body parts.

Reducing heat energy of body parts results in frostbite.