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

If two populations do not mate and produce fertile offspring, separate species result.
If two populations do not mate and produce fertile offspring, what results?

The sun delivers power to the chemical factory chloroplasts.
What delivers power to the chemical factory chloroplasts?

Food chewed evenly during mastication moisten and lubricate the lining of the mouth and this?
Food chewed evenly during mastication moisten and lubricate the lining of the mouth and this?