Wow, ummm science was usually a decently strong point for us, so I'll take a stab at this, but it's just my opinion. Feel free to correct.
Actually, couple of questions first:
When you say math, do you mean calculation or theory?
Which questions were going completely over your head? (as in, which packets/from which providers?)
Also, did you already complete the course in AP Chemistry?*
What other science classes have you taken? (I've found that I learned a lot of the information in AP Physics, Bio, and Chem)
Now, to something that can apply to everyone:
Keeping in mind that you're not going to power every single question (not trying to discourage, definitely work at it) I like to look at it this way. Chances are you'll get the answer eventually, at least by the giveaway clue if you've taken any high level chemistry. Not always, but there's a good chance. But if you want to power something, you need more in-depth knowledge about the subject. I'm of the opinion that reading old questions helps, because it exposes you to the kind of stuff that's actually asked, but I do see what you're getting at with "spottiness."
Here's another possible [related] approach: Figure out what crops up a lot. Read a ton of questions about those particular topics (if you don't already know about them), especially focusing on more obscure clues. I've found it helps not just to memorize what the seemingly confusing stuff they're saying, but to actually understand what processes/concepts they are referring to (since a lot of questions mention a certain property or larger concept that the answer relates to/is a part of in some way).
Now, in addition to just reading questions, which have a narrower focus but pull information from different aspects of that topic (sorry if I'm being a little vague. What I mean to describe is the fact that, for example a question about lactic acid may talk about: structure, formation, chemical/biological processes it's involved in, alternative names, applications/uses) you may find it helpful to use other
[reliable] sources to read up on the same information that is being asked about
, but in more detail. Specifically, don't just read about the answer (in the example, lactic acid), but read about the broader topics they touch upon (such as cellular respiration and the like).
[Granted it may not be obvious what the topic they're referring to is if you don't already have the material down, so it may take a little digging. But you'll only learn more in the process of finding it
]. In this way, you'll be more likely to not only get questions about the topic you saw in the question (say, that lactic acid is formed during fermentation), but you'll hopefully be more prepared to answer any questions about other aspects of cellular respiration.
Also, if you then see some topic that interests you (and preferably could be asked about, but knowledge for knowledge's sake is encouraged as well), start branching out. Read about related topics. Make connections between the different concepts and check to see if these are ever asked about. Remember, you're not just being asked useless trivia. All of these academic questions ought to in some way be of relevance in their respective fields.
Bottom line, if you hear something that goes over your head, don't just dismiss it as an obscure clue. Go look it up. Read into the subject, and see if you can actually form an understanding of the topic, enough to answer that question if asked again, and others related to it.
*I know there's a strong chem/bio focus here, don't think I'm biased. Personally, I'd much rather destroy a physics question. The same general process should apply to any science topics.
(Yes, I know this process is time consuming and can't be done for every question you read/hear, but applying it even a little should help)
Like I may have alluded to before, I'm not necessarily an expert in studying science for quizbowl, so anybody feel free to [kindly, I have feelings too] correct anything I said. Sorry for the long post, not usually my style.