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: What kind of system do echinoderms possess? Answer: water-based circulatory
[EX A]: Echinoderms possess a water-based circulatory system.

[EX Q]: Question: What is the term for the exchange of genetic material between non-sister chromatids of homologous chromosomes? Answer: crossing-over
[EX A]: Crossing-over is the term for the exchange of genetic material between non-sister chromatids of homologous chromosomes.

[EX Q]: Question: What part of the sperm contains the nucleus? Answer: head
[EX A]:
The head of the sperm contains the nucleus.