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.
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Question: Fact 1: Energy is passed up a food chain or web from lower to higher trophic levels. 
Fact 2: Plants represent the first trophic level.

Answer: Energy is passed up a food chain from plants.


Question: Fact 1: Butter is a fat that is a solid at room temperature. 
Fact 2: Some fats are more likely to cause heart disease.

Answer: butter can lead to heart disease.


Question: Fact 1: Plastics are made from petroleum and produce toxic waste. 
Fact 2: Toxic wastes create special problems.

Answer:
Petroleum based products create special problems.