Something funny that I noticed when reading your Bible quote is that it never says straight out that the fruit is an apple! Perhaps it says earlier in the text or perhaps it's just your version of the Bible, but it's still kinda odd... I actually don't think it pinpoints the fruit as an apple in my Swedish version either.
I don't think the any Bible says apple... (scratches head)... but I am not sure...
I think it is just something they say to help tell it to children... just like the Noah and the ark..... they didn't really take only 2 a piece... it was 7 clean and 2 unclean (i think)... but I guess they just change it around to help children learn the Bible stories.. and then we grow up keeping that wording with us...