Biological science is not an area of mere interest for me - it is a passion.
Not a great opening. Too common, and this should be shown through your essay rather than told.
The memory of my first encounter with the subject is crystal clear.
You can cut this and go straight into the narrative.
All of a sudden, an anatomy book caught my eye, and the reading sparked in me a curiosity so strong as to leave me yearning for a profession in the field - at the age of seven.
Better, because more specific than your previous sentences. If it were even more specific, it would be better still. What about the book entranced you? At seven, it seems unlikely that dense descriptions of the human body would do the trick. Were there pictures? Was a particular section of the book of interest? Etc.
My family's strong religious background and the reality they taught me as referenced to creationism only empowered my curiosity, for I became determined to learn the truth about the origins and reasons of life.
Ow. Okay, if you are going to mention this, then you need to make it clear that you absolutely do not believe in Creationism, and have rejected those teachings. If you haven't, and aren't prepared to lie about it, then don't raise the issue at all. Religion is a dangerous topic to raise in an application essay at the best of times, and this particular aspect of the topic, treated in any other way than the one I have described, is likely to get your application thrown in the trash bin faster than you can say "Let there be light." Being a creationist and being a serious academic in any field related to biology is an oxymoron. It's sort of like someone who doesn't believe in the atomic theory of matter trying to become a chemist.
I want to learn how such complex phenomena as free will and thought are created through the reactions of simple substances and chemicals; how simple cells are driven to assemble into such complex organisms that can even come close to understanding not only their world, but the vast truths and intricate laws of the entire universe.
I like this part. You have specific questions you want to research, questions that are especially important given recent scientific discoveries.