Given a scientific question, generate a correct answer to it.

[EX Q]: Name the fever that is caused by a virus that has antigens similar to molecules in human heart tissues.
[EX A]: rheumatic fever

[EX Q]: Do particles collide more in two reactants when they are both in fluid forms or solid forms?
[EX A]: fluid

[EX Q]: Graded potentials are temporary changes in what, the characteristics of which depend on the size of the stimuli?
[EX A]:
membrane voltage