First of all, what is the difference between scales and modes? Aren't both used for making up lines?
Also, which modes best suit each style of music?

If I am making up a Jazz line, is there any note within the scale I shouldn't use for a passing tone?

Do a search for scales and modes, lots of info already posted. Try Here:

C Mixolydian (http://www.talkbass.com/forum/showthread.php?s=&threadid=52844)

or here:

Pacman's method (http://www.talkbass.com/forum/showthread.php?s=&threadid=50170)

or here:

What's the difference (http://www.talkbass.com/forum/showthread.php?s=&threadid=54075)

Here's an article on basic beginning bassline construction:

http://www.talkbass.com/html/modules.php?name=News&file=categories&op=newindex&catid=1

Originally posted by LoreBard

If I am making up a Jazz line, is there any note within the scale I shouldn't use for a passing tone?

Yeah - any one that doesn't fit! ;)