In this task, you are given a question and an answer, you would be asked to create the sentence based on the Question-Answer provided. It should be contained within the Question-Answer provided.

[EX Q]: Question: The atoms of a compound are held together by what type of bonds? Answer: chemical
[EX A]: The atoms of a compound are held together by chemical bonds.

[EX Q]: Question: The outer surface of the heart changes from positive to negative during what? Answer: depolarization
[EX A]: The outer surface of the heart changes from positive to negative during depolarization.

[EX Q]: Question: Which model can be used to trace genetic inheritance? Answer: pedigree chart
[EX A]:
The pedigree chart model can be used to trace genetic inheritance.