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

Q: The pressure of a sample of gas is measured with an open-end manometer.

A: The pressure of a sample of gas is measured with an open-end what?
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Q: Pyramid ecosystem is used to show energy flow through the trophic levels.

A: What is used to show energy flow through the trophic levels?
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Q: An allele that's always expressed over another is a dominant allele.

A:
What's the term for an allele that's always expressed over another?
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