The official name of the SAT II Biology is actually the SAT II Biology E/M. The test has this strange name because it’s actually two tests built into one. One test, the Biology E Test, emphasizes ecology and evolution. The other test, the Biology M Test, emphasizes molecular biology and evolution. On test day, you will take either the Biology E or the Biology M test. You can’t take both.

The Biology E and Biology M Tests aren’t completely dissimilar. In fact, out of a total of 80 questions, the two tests share a core of the same 60 questions. The test contains an additional 40 questions, split between the E and M specialty sections. So if you take the Biology E test, you will only have to answer the section of 20 ecology and evolution questions. If you take the Biology M, you need only answer the molecular biology and evolution section.