TASK DEFINITION: Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
PROBLEM: Monatomic ions form when a single atom gains or loses electrons.

SOLUTION: What form when a single atom gains or loses electrons?

PROBLEM: Volvox sphere has a distinct front and back end.

SOLUTION: What has a distinct front and back end?

PROBLEM: Amount of yearly rainfall causes the greatest change in a grassy field over time.

SOLUTION:
Which causes the GREATEST change in a grassy field over time?