A great way to discover topics worth researching is to review science news for the general public. Browse through science news to read about current research to learn how advances in chemistry are reported.
This is a biochemistry class. In your research proposals, be sure to identify a specific aspect of your topic that can be analyzed biochemically.
For example, cows contributing to methane emissions could be an interesting topic. One of the biochemical aspects of the topic is to explore the question of how cows produce methane.
You can also try to search for articles aimed at the informed lay person (from newspapers and publications such as Scientific American, Discover, etc.).
Academic Search Complete (Tip: run a search, then use the Source Type options to select Newspapers, Magazines, or Trade Publications.)
Once you are comfortable with lay articles on the topic, look for review articles that are aimed at other scientists. These will give you an good overview of the issues in the field. You can search for review articles a number of ways including within a specific journal, within a database, or by searching review collections such as Annual Reviews.
For quick, basic definitions and ideas to get you started, try Wikipedia.
For a more authoritative scientific encyclopedia that includes references, try AccessScience (whose content comes from the McGraw-Hill Encyclopedia of Science & Technology) or the Sage Reference Collection (this is especially rich for topics related to environmental issues).
When you're ready to find articles from scholarly journals, use the Article Databases.