Not a bassoon player but, first thing is to listen. Get recordings of the excerpts, or find some on YouTube*. Listen to hear what these should sound like.
If you can get the whole part practice the music before the excerpt and after the excerpt. You will be amazed at how differently you will look at the music in relation to what you play before and after. Remember that musicality is better than technical proficiency. Although they do want a certain level of technical ability, they do want to hear you play musically.
*Regarding Youtube - be careful of what you find. Big name orchestras are good. Be careful with john smith's version, he may not know enough about the style or period to play it correctly.
Re: Orchestra auditions 14:21 on Wednesday, August 12, 2009