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

Q: The long, threadlike extensions of the nerve cell help transmit nerve impulses.

A: Which part of the nerve cell helps transmit nerve impulses?
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Q: Competive exclusion princple explains why two different species cannot occupy the same niche in the same place for very long.

A: What explains why two different species cannot occupy the same niche in the same place for very long?
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Q: The two parathyroid glands are located behind the thyroid gland.

A:
The two parathyroid glands are located behind what gland?
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