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

[EX Q]: Lichens are not a single organism, but rather an example of a mutualism.
[EX A]: Lichens are not a single organism, but rather an example of a what?

[EX Q]: The cells in the follicle undergo physical changes and produce a structure called a corpus luteum.
[EX A]: The cells in the follicle undergo physical changes and produce a structure called a what?

[EX Q]: Because of the wave character of matter, the idea of well-defined orbits gives way to a model in which there is a cloud of probability.
[EX A]:
Because of the wave character of matter, the idea of well-defined orbits gives way to a model in which there is a cloud of what?