Great question - Natural Sciences RC passages can definitely be intimidating and time-consuming, but they don't need to be that way. Keep in mind a few things:

1) The subjects that they tend to cover are things like astronomy, biology, botany, etc. - it's the type of material with which few b-school applicants are familiar. The reason? They want to intimidate everyone with something outside of your comfort zone...know that that's the case going in.

2) Because of that, b-schools don't much care whether you can become knowledgeable on those topics - they're not too relevant to your success in business school. Your job is to approach these passages as a manager would: you need to know what the author is trying to accomplish.

3) Technical terms are both intimidating and largely irrelevant...don't worry if you don't understand or can't process scientific jargon. You may even want to replace those words mentally with variables - "Once the Y process is complete, the X phase begins". Any particular details that are important, you can go back to revisit later.

There are a few strategies that will help you both read and answer the questions more effectively:

1) Try to understand what the author is trying to accomplish with each paragraph. If your synopsis of paragraph 1 is "describe the old theory regarding immunological reactions", that's a great start. You won't need to immediately know what that theory is, specifically.

2) Anchor yourself by looking for keywords that you know signal the author's intent or organization - words like "however", "furthermore", "therefore", etc., and numerical terms ("a second theory..."). You're definitely responsible for these words, and they'll help you quite a bit with the above. Focus on the words you know, and don't worry as much about the others.

3) When you are looking for specific details as prompted by the questions, make sure you understand the question, as it's usually much more important than anything else. They tend to ask about cause-effect relationships quite a bit, and the most likely way they'll trap you is to ask you for, say, the cause of a scientific situation, and bait you toward picking the answer choice that expresses the effect. If you've noted the purpose of each paragraph, you'll know where to look for the specific-detail answers...then you need to make sure you're answering the correct question.

These strategies should help quite a bit - my first GMAT teaching experience with Reading Comp, I realized I was going to have to teach an RC passage about immunological reactions, and I couldn't force myself to understand the content. By applying the strategies above, though, I could answer all of the questions relatively easily, and realized in doing so that most of the content was just there to intimidate me and waste my time/energy.

wow, Brian, that was very detailed and just what I was looking for! that's some great advice. i greatly appreciate your reply. i will apply that to my practice - we'll see what happens! I'll be sure to keep you, and the community, updated.

Again, if anyone else has hints/suggestions, feel free to post.

one last addition to this... what i've found works for me is going into every RC passage telling myself "I am generally interested in this topic". try it a couple times while practicing and see if it makes a difference. I've actually caught myself going off the deep end a couple words in and started the passage over after taking a deep breath and really focusing...

i also had a tendency to get caught up on trying to pronounce the words correctly in my head. this would add to the frustration... so now whatever i say first i just go with that but visually remember what the word looked like in case they refer to it in the answers... seems small but it helps me