Given a scientific passage and an answer, generate a question for the given answer.

Q: Passage: Centrioles are rod-like structures made of short microtubules. Nine groups of three microtubules make up each centriole. Two perpendicular centrioles make up the centrosome . Centrioles are very important in cellular division, where they arrange the mitotic spindles that pull the chromosome apart during mitosis. Answer: centrioles

A: What are the rod-like structures made of short microtubules that play an important part in cellular division?
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Q: Passage: Acidity is measured on a pH scale. Rain that is 5.0 or less on that scale is considered acid rain. Answer: ph scale

A: Acidity is measured on what kind of scale?
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Q: Passage: Spermatogenesis produces four haploid sperm cells, while oogenesis produces one mature ovum. Answer: ovum

A:
While spermatogenesis produces four haploid sperm cells, oogenesis produces one mature what?
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