The exam is three hours long and consists of two sections:

Section I (90 minutes; 60% of total grade)

This first section consists of 120 multiple-choice questions. According to the College Board:

"To be broad enough in scope ... this section must be so comprehensive that no student should be expected to attain a perfect or near-perfect score. Thought-provoking problems and questions based on fundamental ideas from biology are included along with questions based on the recall of basic facts and major concepts."

In plain English: it's a difficult exam and you are expected to miss a lot of questions.

As a correction for haphazard guessing, the College Board will deduct one-fourth of a point for each question answered incorrectly. Guessing on the exam is covered thoroughly in the strategies section.

Section II (90 minutes; 40% of student's total grade)

The second section of the exam consists of four equally weighted free-response questions. One essay question is ususally taken from the area of Molecules and Cells and another question focuses on Heredity and Evolution. The remaining two questions generally focus on Organisms and Populations.

The College Board expects you to "demonstrate reasoning and analytical skills, as well as an ability to synthesize material from several sources into a cogent and coherent essay."