Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Q: Living organisms are made up of biochemical type of carbon-based compounds.

A: Living organisms are made up of what type of carbon-based compounds?
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Q: Seismologists originally measured the intensity of an earthquake with the mercalli scale.

A: How did seismologists originally measure the intensity of an earthquake?
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Q: Lack of fertilization causes the menstrual cycle to be repeated.

A:
What causes the menstrual cycle to be repeated?
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