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: Plasmodesmata connect to cytoplasms in the plant cell.

A: What do plasmodesmata connect to in the plant cell?
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Q: The human body has as many as two trillion lymphocytes, and lymphocytes make up about 25% of all of leukocytes.

A:
The human body has as many as two trillion lymphocytes, and lymphocytes make up about 25% of all of what?
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