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.

Question: When does exchange of dna segments happen between non-sister chromatids of homologous chromosomes? Answer: during crossing-over
Exchange of dna segments happens between non-sister chromatids of homologous chromosomes during crossing-over.

Question: What type of function does the long bone perform? Answer: work as lever
The long bone work as lever.

Question: What element is a biochemical compound based on? Answer: carbon

Carbon element is a biochemical compound based on.