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

[EX Q]: Embryos usually don't survive if they have extra or too few of these genetic units?
[EX A]: Embryos usually don't survive if they have extra or too few of these genetic units?

[EX Q]: The action of flushing the toilet, performed multiple times daily, is the single biggest use of water in the home.
[EX A]: What action, performed multiple times daily, is the single biggest use of water in the home?

[EX Q]: Compounds like sodium chloride form structures called crystals.
[EX A]:
Compounds like sodium chloride form structures called what?