Given a scientific passage and an answer, generate a question for the given answer.
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Question: Passage: The Universe contains about a hundred billion galaxies. Answer: about a hundred billion

Answer: Approximately how many galaxies are there in the universe?

Question: Passage: The haploid gametophyte produces the gametes, or sperm and egg, by mitosis. Remember, gametes are haploid, having one set of chromosomes. Answer: mitosis

Answer: By what process does the haploid gametophyte produce the gametes?

Question: Passage: Learning is a change in behavior that occurs as a result of experience. Answer: learning

Answer:
What word describes a change in behavior that occurs as a result of experience?