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: Gametes then unite in fertilization and form a diploid zygote. 
Fact 2: Zygotes are diploid and undergo cell division to become an embryo.

SOLUTION: Gametes then unite in fertilization and eventually become an embryo.

PROBLEM: Fact 1: Mammals conserve body heat with their hair or fur. 
Fact 2: Mammals Hair or fur covers the bodies of most mammals.

SOLUTION: Mammals conserve body heat with their fuzzy, protective covering.

PROBLEM: Fact 1: Viruses often infect bacteria. 
Fact 2: Phages, or bacteriophages are viruses that infect bacteria.

SOLUTION:
Bacteriophages infect bacteria.