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.

Example Input: Fact 1: soil is formed by weathering. 
Fact 2: Soils are formed by breakdown of rock.
Example Output: Weathering is the breakdown of rock.

Example Input: Fact 1: Complex chemistry is needed to carry out all the functions of life. 
Fact 2: Life functions of cell growth and reproduction are seen.
Example Output: Complex chemistry is needed to carry out cell growth and reproduction.

Example Input: Fact 1: Fertilization occurs when a sperm and an egg fuse to form a diploid zygote. 
Fact 2: Familiar types of gamete include the female ovum , or egg cell, and the male sperm cell.
Example Output:
Fertilization occurs when the male and female gametes fuse to form a diploid zygote.