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: Viruses cannot reproduce by themselves. 
Fact 2: Viruses include the Tobacco Mosaic Virus.
The Tobacco Mosaic Virus cannot reproduce by itself.

Fact 1: Babies that are very large or very small at birth are less likely to survive. 
Fact 2: Poor nutrition while in the womb is the major reason why babies are small at birth.
Babies who had poor nutrition while in the womb are less likely to survive.

Fact 1: Molecules of DNA are encoded with instructions that tell cells what to do. 
Fact 2: Genes are parts of DNA molecules.

Genes are instructions that tell cells what to do.