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

Q: Resonance is the term for the use of two or more lewis structures to represent the covalent bonding in a molecule.

A: What is the term for the use of two or more lewis structures to represent the covalent bonding in a molecule?
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Q: The ileocecal valve, a sphincter, is usually in a constricted state, but when motility in the ileum increases, this sphincter relaxes, allowing food residue to enter the first portion of large intestine.

A: The ileocecal valve, a sphincter, is usually in a constricted state, but when motility in the ileum increases, this sphincter relaxes, allowing food residue to enter the first portion of what?
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Q: Sickle cell diseas is caused by receccisve allele.

A:
Sickle cell diseas is caused by what?
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