I am taking a bio-psychology class and once a week I need to read a journal article and do a summary about the journal.

I am taking a bio-psychology class and once a week I need to read a journal article and do a summary about the journal. I wrote an article about anxiety in preschool children but my professor would not accept it because I didn't put anything about biology in the article. My question is could you please give me some ideas about biology in bio-psychology. I am sure I am making this more completed than what it is and Google is not my friend right now. LOL