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

Q: Carried through body happens if cancer cells enter the blood stream.

A: What happens if cancer cells enter the blood stream?
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Q: Population is an important level of organization in ecology and the unit of microevolution.

A: What is an important level of organization in ecology and the unit of microevolution?
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Q: Inflammatory response is the second line of defense.

A:
What is the second line of defense?
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