Problem:

Q: What are the earliest and simplest vertebrates?   A:
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A: fish


Problem:

Q: What basic structure holds plants upright, bears leaves and other structures, and transports fluids between roots and leaves?   A:
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A: stem


Problem:

Q: What waves do radio and television use?   A:
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A: radio waves


Problem:

Q: What part of blood releases clotting factors?   A:
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A: