Given a scientific passage and an answer, generate a question for the given answer.

Let me give you an example: Passage: A frameshift mutation is a deletion or insertion of one or more nucleotides that changes the reading frame of the base sequence. Deletions remove nucleotides, and insertions add nucleotides. Consider the following sequence of bases in RNA:. Answer: nucleotides.
The answer to this example can be: A frameshift mutation is a deletion or insertion of one or more of what that changes the reading frame of the base sequence?
Here is why: The science passage defines frame mutation and the main compoment here is nucleotides. Hence the generated question is apt.

OK. solve this:
Passage: For many decades, scientists have known that atoms consist of electrons and other particles called protons and neutrons. Recently they found that there are even smaller particles in atoms. Scientists call these extremely tiny particles by the funny name of quarks. As you can see in this diagram, there are several different kinds of quarks, called up quarks, down quarks, top quarks, bottom quarks, charm quarks, and strange quarks. In this chapter you'll learn about these unusual particles and also other particles inside the atom. Answer: neutrons
Answer:
For many decades, scientists have known that atoms consist of electrons and other particles called protons and?