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

[EX Q]: When an atom gains or loses an electron it becames a(n) ion.
[EX A]: When an atom gains or loses an electron it becames an?

[EX Q]: Cell -> tissue -> organ -> organ system sequence represents the correct levels of organization for multicellular organisms.
[EX A]: Which sequence represents the correct levels of organization for multicellular organisms?

[EX Q]: All of the land drained by a river system is called its basin, or the "wet" term watershed
[EX A]:
All of the land drained by a river system is called its basin, or what "wet" term?