I just had a lecture about nucleosynthesis in stars and supernovae, but a couple of things I don't understand:

1. Why is there a relatively lower amount of Beryllium and Boron produced in stars?

2. During a type II supernova, free neutrons are released which collide with Iron nuclei and are absorbed to form heavier isotopes. The neutrons may then go on to spontaneously decay into a proton and electron to produce a heavier element. My question is, do neutrons regularly decay when bound to a nucleus? What effect does that have when, say, that nucleus or atom is a part of a molecule which is part of a human body?

don't really know about #1, but for #2 in general all of the particles decay at some rate (even protons have a half life). I believe some isotopes of the heavier elements tend to be more unstable so they tend to undergo radioactive decay more readily. With regards to the human body, my opinion would be that most of the elements that comprise the human body (C,H,O,N,P) are stable enough that radioactive decay isn't an issue.