what do these idioms mean,please?

[Lama1]

an apple of discord
until / till / to the bitter end
be at the bottom of
could you please provide examples?
thanks

[Mister Micawber]

an apple of discord - a point of disagreement, causing argument or conflict
until / till / to the bitter end -- until the final conclusion
be at the bottom of - be the basis of, be the original cause of

You can find many examples by googling each phrase. If you are unsure of their accuracy, post them here and we will check them for you.
_________________
Native English teacher at Mister Micawber's

[Lama1]

thank you very much for your help,Mister Micawber.