Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Vesicles are basic tools of the cell for organizing metabolism, transport, and storage of molecules.
What are basic tools of the cell for organizing metabolism, transport, and storage of molecules?

Fermat’s principle states that light will always take the path of the least amount of time.
Fermat’s principle states that light will always take the path of least amount of?

Like the strings of cello, anything that vibrates produces waves of energy.

Like the strings of cello, anything that vibrates produces waves of what?