AP Biology Exam: 2021 Results

The following data reflect the 212,198 students worldwide who took either the paper or the digital AP Biology Exam in May. Data from students who tested in June are not yet available.

AP Biology score distributions, 2018 and 2019 vs. 2021

The following table enables comparisons of student performance in 2021 to student performance on the comparable full-length exam prior to the covid-19 pandemic. AP Biology teachers seem to have weathered the challenges of this year remarkably well, such that the 2021 AP score distributions are very similar to those of 2018, and just slightly lower than those of 2019. (Because the 2020 exam had fewer free-response questions and no multiple-choice section, it is not on the same score scale.)

Of these 212,198 students, 1 student achieved a perfect score from all professors/readers on all free-response questions and correctly answered every multiple-choice question, resulting in the rare and impressive feat of earning all 120 of 120 points possible on an AP Biology Exam.

The May 14 In-School Paper Exam

The largest exam date for AP Biology was May 14, so the following information is specific to the exam version administered on that date.

As usual in this subject, students scored significantly higher on the multiple-choice section than on the free-response questions.

Multiple-choice section:

• Course Units:
• AP Biology students demonstrated exceptionally strong mastery of Unit 7, Natural Selection, with 43% of students answering virtually every question about this unit correctly. Student understanding of Unit 8, Ecology, was also strong, with 26% of students answering virtually every question right.
• The unit on which AP Biology students earned the lowest scores was Unit 2, Cell Structure and Function.
• Big Ideas:
• Students had a much greater understanding of Big Idea 1, Evolution, than they did of the other 3 Big Ideas. 33% of students answered virtually every question about Big Idea 1 correctly.
• Skill Categories:
• AP Biology students’ strongest skill was representing and describing data (Skill Category 4). A massive 33% of students achieved perfect scores on this skill, not missing a single such point on the exam. Students also demonstrated solid proficiency with Skill Category 3, Questions and Methods.
• AP Biology students’ weakest skill was generally Skill Category 5, Statistical Tests and Data Analysis. 6% of students achieved perfect scores on this skill. 16% of students received 0–1 points across this category of questions.

Free-response section:

• Question 4, about finches in the Galápagos islands, is the question that best identified students who should receive college credit from those who should take Introductory Biology in college, using their AP course as a foundation. It’s a tough question, but if a student could answer 1 of the 4 parts of the question, the student was competitive with college students who had completed the corresponding college course, and so most students earning 1 point on this question are earning enough points elsewhere on the exam to receive an AP score of 3. Students who could answer 2 of the 4 parts are generally earning enough points across the exam to receive an AP score of 4. And students who could answer 3 or 4 of the parts are generally earning enough points across the exam to receive an AP score of 5.
• But it’s also important to recognize the efforts of students who do not qualify for a score of 3+, but who nonetheless developed basic understandings and skills in the course. As a reminder, the most recent research on students who receive a 2 in AP Biology finds that students who score a 2 in AP Biology proceed to earn higher grades when taking the course in college than students with the same high school GPA, SAT score, race, and gender. Question 1 provides a good indication of whether a student will qualify for a 2. Students who can only earn the first point on this question (by describing the characteristics of a plasma membrane that prevent simple diffusion) are generally earning enough points throughout the exam to qualify for a 2, but not for a 3 or higher.

The May 27 Digital Exams

To support student access, different testing modes—paper and digital—were essential. To protect exam security, many different exam versions were necessary. Accordingly, to provide students with similar opportunities for success regardless of which version they took, each version of the exam had to be analyzed separately by psychometricians to identify its unique difficulty level so that standards for scores of 3, 4, and 5 could then be separately identified for each exam version. Analyses focused on:

• Differences in the testing mode (paper or digital). For sections of the exam that proved easier to take digitally, the digital versions require more points for each AP score. For sections of the exam that proved easier to take on paper, the paper exam requires more points for each AP score.
• Differences in the difficulty of specific questions. When exam questions prove easier, more points are required for each AP score, and when exam questions prove more difficult, fewer points are required on one version than another.
• Differences in versions of the exams. The net result for this year’s AP Biology Exams is that out of 120 points possible, most of the digital versions were more difficult than the paper version, a few of the digital versions were easier than the paper version, and a few were the same difficulty as the paper version. As a result:
• On the easiest digital version, a student needed to earn 3 more points to receive an AP score of 5 than students who took the paper version.
• On the hardest digital version, a student needed to earn 12 fewer points to receive an AP score of 5 than students who took the paper version.