There are several ways to 'classify' Biology / Life Science information, based on what each type is useful for. Learn the definitions below, so when your Professors ask you to find '___' information, you'll understand exactly what they want.

Scholarly information comes from articles that were written by scholars who perform research, write up the results of their studies into articles, which often end up being reviewed by their peers, then published in scholarly journals.

Scholars are subject experts.Their articles are meant to inform their fellow scholars in their community, are very dense, and also have discipline-specific 'jargon' as well - which they assume the reader already understands.

Participating in this scholarly publishing cycle is how academics, professional researchers, and scientists both craft a career and push the envelope of human knowledge in our culture. That is the main reason for the traditional perception of scholars and scientists as 'experts', to whom journalists often turn to, for example,  for information for an article or newscast.

Popular information sources contain shorter, less dense articles for the general public. You don't have to be an expert to understand them!  Professional journalists (such as science journalists), some of them specializing in a particular topic area, write these for popular magazines. But remember that journalists did not themselves do the research - they're professional writers doing their best to 'translate' the nuances of research (especially scientific research) for the rest of us who aren't experts.

Primary Sources

Original research or data. Primary sources can include any of the following publications:

• Journal Articles -- Journal articles can be primary sources if they contain original research, but keep in mind that not all journal articles are primary sources.
• Reports -- Reports are publications on research that are published independently of a journal. They are often published by governments or companies.
• Theses and Dissertations -- Theses and Dissertations are the original research of an academic working on a degree. 
• Conference Proceedings -- Conference Proceedings are a collection of papers that have been presented at a conference. 
• Published Data -- Data can be considered a primary source, as it is the product of original research.

Secondary Sources

In the sciences secondary sources analyze, interpret, summarize, or evaluate the findings of primary sources. Secondary sources can include any of the following publications: 

• Journal review articles -- A review article summarizes past research on a given topic. Review articles can range from highly intensive systematic or integrative reviews or less rigorous literature reviews.
• Monographs -- A monograph is a book-length scholarly publication dedicated to a single topic. 

Secondary sources can save you time by providing information on the current state of knowledge on a given topic, and also as a way to find primary resources. If you are interested to know what are important, seminal papers in on a topic look at what papers are cited in a textbook on that topic. Review papers can give you in-depth information on a particular research area. Secondary resources are also often less technical than primary resources. 

Tertiary Sources

In the sciences tertiary resources are synthesized from primary and secondary resources. They usually provide summaries on the current state of knowledge, and can be viewed as a jumping off point for your own research. They provide succinct summaries on topics, and can be a good way to familiarize yourself with the terminology on a topic before you begin searching the databases.Tertiary sources can include the following publications:

• Encyclopedias
• Dictionaries 
• Factbooks 
• Almanacs 
• Textbooks