The databases below are good places to search for peer-reviewed articles about biology.
Searching a scholarly database works a little differently than the typical Google or web search that you are probably used to. Here is the process you can take to come up with an effective search strategy:
Here is an example of what a scholarly database search would look like for the following research question: What impact is global climate changing having on coastal environments in Maryland? Note that the quotation marks tell the database to search those words as a phrase (so we'll find articles that say "global warming" as a phrase, rather than articles that say "global" in one paragraph and "warming" in another, for example).
Peer review is a process that most scholarly articles go through prior to publication. When authors submit their research to an academic journal, that journal's editorial board will send it along to peer reviewers, who are other researchers that are knowledgeable about the topic that the article is about. The reviewers read it and leave comments on the overall quality of the article. Then, the authors will usually have the opportunity to make revisions to the article based on these comments, resubmit, and hopefully get published.
The video below from North Carolina State University is a 3 minute overview of the peer review process.