TASK DEFINITION: Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
PROBLEM: Temperature and ph level are important in the activity of an enzyme.

SOLUTION: Temperature and what other environmental factor are important in the activity of an enzyme?

PROBLEM: The reverse process of moving material into a cell is the process of exocytosis.

SOLUTION: The reverse process of moving material into a cell is the process of what?

PROBLEM: Fractional crystallization is the separation of compounds on the basis of their solubilities in a given solvent.

SOLUTION:
What is the separation of compounds on the basis of their solubilities in a given solvent?