You cannot use Control+F, so I recommend that if you're doing that now during your practice to stop, so you don't get dependent on it. There is a highlighting feature that is very useful for identifying key terms and definitions, important facts and numbers, and main ideas.
I would suggest broadening your exposure to scientific papers. The OAT has science-based passages. Mine was about bats, drug addiction, and tissue engineering. They're not as intensive as a journal publication but try reading general science articles. You can try reading articles from ScienceDaily or other websites that have general science articles made for broad audiences. The more you're used to scientific papers, the easier it'll be to do the RC section
Here's a link:
Biology News
In terms of a method for improving, you can try the search and destroy method as some other students have mentioned in this forum. For me, I briefly skimmed over the passage once, using the highlighting feature to highlight what I believed to be important, then doing the multiple-choice.
Kaplan has suggested on your scrap board/paper, you can organize the paragraphs by topic/main idea so when you do the MC, you can trace it back to a certain paragraph based on what the MC is asking.
Hope this helps!