BIO 311C Textbook

<p>I was looking on the co-op website to see what book I would need for bio 311c. Specifically for Fritz, it only says 9th edition. Does it make a difference if I use the 8th edition textbook for her class? Also, the website would only let me look at books under the summer term. Is there a difference between possible books for summer and fall term? Thanks.</p>