TASK DEFINITION: Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
PROBLEM: Most ferns produce the same type of spores and are therefore called homosporous.

SOLUTION: Most ferns produce the same type of spores and are therefore called what?

PROBLEM: Renewable energy sources emit fewer or no greenhouse gases.

SOLUTION: What type energy sources emit fewer or no greenhouse gases?

PROBLEM: Water are most cells surrounded by.

SOLUTION:
What are most cells surrounded by?