TASK DEFINITION: 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.
PROBLEM: Fact 1: hearing is used for sensing sound by animals. 
Fact 2: All cats are animals.

SOLUTION: hearing is used for sensing sound by cats.

PROBLEM: Fact 1: bacteria cause food poisoning. 
Fact 2: Food is flash-frozen to kill parasites and bacteria.

SOLUTION: Flash freezing food can prevent illnesses that result from poisoning.

PROBLEM: Fact 1: Mutations that lead to cancer usually occur in genes that control the cell cycle. 
Fact 2: Mutations in genes that control the cell cycle are found in virtually all cancer cells.

SOLUTION:
mutations are found in genes.