TASK DEFINITION: Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
PROBLEM: Mesoderm type of cell layer do flatworms have.

SOLUTION: What type of cell layer do flatworms have?

PROBLEM: Evolution occurs by natural selection, a process whereby better-adapted members pass along their traits, according to darwin.

SOLUTION: Evolution occurs by what process whereby better-adapted members pass along their traits, according to darwin?

PROBLEM: Life cycle is the term for the span in the life of an organism from one generation to the next.

SOLUTION:
What is the term for the span in the life of an organism from one generation to the next?