Given a scientific question and its correct answer, generate supporting facts for the answer. This supporting fact can be an explanation for the answer to the given question.

Ex Input:
Question: What occurs when two wave crests overlap? Answer: constructive interference

Ex Output:
Constructive interference occurs when two wave crests overlap, doubling the wave amplitude at that location.

Ex Input:
Question: The female reproductive organs include the ovaries, fallopian tubes, uterus, and what? Answer: vagina

Ex Output:
The female reproductive organs include the ovaries, fallopian tubes, uterus, and vagina.

Ex Input:
Question: If an atom gains electrons, it becomes what? Answer: an ion

Ex Output:
If an atom gains electrons, it becomes an ion. Is the ion positively or negatively charged? Explain your answer.