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

Q: Passage: The last major ice age took place in the Pleistocene. This epoch lasted from 2 million to 14,000 years ago. Earth's temperature was only 5 C (9 F) cooler than it is today. But glaciers covered much of the Northern Hemisphere. In Figure below , you can see how far south they went. Clearly, a small change in temperature can have a big impact on the planet. Humans lived during this ice age. Answer: pleistocene

A: The last major ice age took place in which era?
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Q: Passage: Meiosis is the type of cell division that produces gametes. Answer: meiosis

A: What is the type of cell division that produces gametes?
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Q: Passage: assigned a unique one-, two-, or three-letter symbol. The names of the elements are listed in the periodic table, along with their symbols, atomic numbers, and atomic masses. The chemistry of each element is determined by its number of protons and electrons. In a neutral atom, the number of electrons equals the number of protons. Answer: protons and electrons

A:
The chemistry of each element is determined by its number of what?
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