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

Q: Constructive interference is when two waves combine to create a larger wave.

A: What is it called when two waves combine to create a larger wave?
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Q: Gastro-esophageal sphincter sphincter is located at the stomach end of the esophagus and opens to allow the bolus to enter the stomach.

A: Which sphincter is located at the stomach end of the esophagus and opens to allow the bolus to enter the stomach?
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Q: Plant cells have structures that animal cells lack.

A:
Plant cells have structures that animal cells?
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