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

[Q]: Radioactivity is the release of particles and/or energy from the nucleus of an atom.
[A]: What is the release of particles and/or energy from the nucleus of an atom described as?


[Q]: The mitochondria organelles are known as the "power plants" of the cell.
[A]: What organelles are known as the "power plants" of the cell?


[Q]: In heart muscle, acetylcholine released by neurons activates a signal transduction pathway.
[A]:
In heart muscle, what released by neurons activates a signal transduction pathway?