My suggestion is to take a look at the
beginnings of the sample essays with top scores in the
AAMC Official Guide to the MCAT Exam.
My score last year was a Q, which I was not very happy with considering I come from a writing intensive background.
In my retest review, I spent a lot of time looking at the sample essays in the above book, making careful note of the stylistic techniques used in a good opening.
DO NOT open with "The statement means..." Instead, bust out with a famous quote, marginally related example, etc.
I did this the second time around. Although my organization and ability to stay on task with my retest on the writing was far worse, I hit an S.
This leads me to believe that they are reading these essays so fast that the grader is forming his/her opinion in the first one or two lines.
Work on a stylized opening and I bet you will be very happy with your results.