What is the key code for the Holt "Modern Biology" online textbook?

To access the online version of the Holt "Modern Biology" textbook, students need to obtain a key code for the book. Holt assigns a key code to schools that register for its online programs. If students do not have this code, they should ask their school's technology administrator for it.

A student's school or class may already have a username and password assigned for access to the online textbook. If one has not been created, the student should register as a new user. Holt also provides online supplementary activities to go along with the units in the "Modern Biology" textbook.