TASK DEFINITION: Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
PROBLEM: Prokaryotes group of simple organisms recycles nutrients and has been on earth since long before multicellular life appeared.

SOLUTION: What group of simple organisms recycles nutrients and has been on earth since long before multicellular life appeared?

PROBLEM: Stimulation of triglyceride breakdown is the first direct action of growth hormone.

SOLUTION: What is the first direct action of growth hormone?

PROBLEM: In living systems, diffusion of substances into and out of cells is mediated by the plasma membrane.

SOLUTION:
In living systems, diffusion of substances into and out of cells is mediated by the what?