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The Complete AP Biology Review Guide for 2021

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Posted by Samantha Lindsay | Jul 19, 2020 4:00:00 PM

Advanced Placement (AP)



Reviewing for the AP Biology exam can seem daunting. There's so much material to cover, and much of it is highly complex. However, if you plan your time well and use appropriate study materials and strategies, you can expect a great score on the exam.

In this article, I'll give you an overview of what the AP Biology exam is like, what you need to know to ace it, and how you can use your study time effectively before the exam on Friday, May 14, 2021, at 8AM!



2021 AP Test Changes Due to COVID-19

Due to the ongoing COVID-19 coronavirus pandemic, AP tests will now be held over three different sessions between May and June. Your test dates, and whether or not your tests will be online or on paper, will depend on your school. To learn more about how all of this is going to work and get the latest information on test dates, AP online review, and what these changes means for you, be sure to check out our 2021 AP COVID-19 FAQ article.


What's the Format of the AP Biology Exam?

The AP Biology exam is a long testthree hours long to be exact. Starting in 2020, the Bio test underwent some key structural changes in terms of questions and format, so it's important that you know what to expect and exactly how the test is structured.

Like other AP tests, AP Biology has two parts: a multiple-choice section and a free-response section, each of which is worth 50% of your overall score. These sections are then divided further into different types of questions.

The multiple-choice section is the first section. It consists of 60 multiple-choice questions and is one hour and 30 minutes long. Each question contains four answer choices. (From 2013 to 2019, this section of the AP Bio test had 63 multiple-choice questions and six grid-in questions.)

Although you have one minute for each question, I would recommend keeping your pace at under a minute per question on your first pass through the section. This way you'll have some extra time at the end to go back and answer any tricky questions you skipped or guessed on.

There's no guessing penalty on the test, so you should answer every question, even if you have no idea which choice is correct (after you've tried to figure it out of course!).

The free-response section, which also lasts an hour and 30 minutes, is made up of six questions: four short-answer questions and two long questions. The short-answer questions are worth 4 points each, whereas the long questions are worth 8-10 points each. (From 2013 to 2019, this Bio section had two long questions and six short-answer questions.)

You'll need to pace yourself wisely on this section. Divided up evenly, this would mean you'd get 15 minutes per question. However, try to spend no more than 10 minutes on each short answer. I recommend doing the short answers first to get yourself warmed up.

Then, if you manage your time well, you should have at least 20-25 minutes for each long free-response questions.

Here's a chart showing the current format of the AP Biology exam:

  Multiple-Choice Section Free-Response Section
Time 90 minutes 90 minutes
# of Questions 60 multiple-choice questions 4 short-answer questions, 2 long questions
Percentage of Total Score 50% 50%


And just to make things clear, here's what the test used to look like from 2013 to 2019:

  Multiple-Choice Section Free-Response Section
Time 90 minutes 90 minutes
# of Questions 63 multiple-choice questions, 6 grid-in questions 6 short-answer questions, 2 long questions
Percentage of Total Score 50% 50%



body_marathon-3.jpgThe AP Biology exam is a marathon, not a sprint. If it helps, during the test you can think about how lucky you are to be taking a test and not running an actual marathon.


What Do Questions Look Like on the AP Biology Exam?

You now know the general format of the AP Biology test, but what do questions actually look like on it? And what kinds of topics do they test? Let's take a look.


Multiple-Choice Questions

As a reminder, there are 60 multiple-choice questions on the AP Bio exam. These can be discrete (meaning they are stand-alone questions) or they can come in sets with other questions.

Here's an example of a multiple-choice question you might see on the exam:


You don't necessarily need lots of in-depth biology knowledge to answer this. The answer is A because the total volume of gas wouldn't change (and oxygen consumption would be immeasurable) unless the carbon dioxide produced by the organisms were removed from the environment.

You can see this from the information contained in the question. This question is part of a group of three questions that pertain to the experiment and data chart. You'll see many question clusters like this in the multiple-choice section.


Grid-In Questions

From 2013 to 2019, the multiple-choice section of the AP Biology exam included six math-based grid-in questions. Starting in 2020, however, the exam will no longer have any grid-ins.Yay!


Short-Answer Questions

On the second section of the AP Biology exam, you'll get four short-answer questions (in addition to two long questions). These questions focus on the following topics:

  • Scientific Investigation
  • Conceptual Analysis
  • Analysis of Model or Visual Representation
  • Analysis of Data

Here's an example of a short free-response question from the 2013 exam:


This question requires an understanding of how evolution shapes the formation of new species (one of the "Big Ideas" of AP biology, which I'll talk about in the next section).

To get the correct answer, you'll need to know the facts about evolution—but you'll also need to be able to apply that knowledge to make inferences about this specific scenario.

This is why a deeper understanding of the main topics in AP Biology is so critical: the difference between knowing the facts about something and comprehending how it works can be surprisingly large.


Long Questions

In addition to the four short-answer questions you'll get on the second part of the AP Bio exam, you'll get two long questions. Both of these focus on "interpreting and evaluating experimental results," with one requiring graphing (per the College Board description).

Here's an example of a long question:


This question is heavy on analysis and isn't just testing your straight-up biology knowledge. Here, you need to be able to read and understand the graphs and table so you can use them to inform your answer to the question.

Once again, an understanding of evolution and the ability to apply that knowledge to a specific scenario is critical.


What Topics Does the AP Biology Exam Cover? 4 Big Ideas

According to the College Board's Course Description, AP Bio has shifted its focus from the content-heavy, memorization-based curriculum that defined the course and exam in the past to become a more concept-driven test.

The goal is for students to gain a deeper conceptual understanding of topics in biology. Reasoning skills and knowledge of the process of scientific inquiry are more important on the current version of the AP Biology test than they have ever been before.

The College Board has tried to structure the exam so that content knowledge and reasoning skills are intertwined. This can be both good and bad. The good is that you won't necessarily have to memorize as many little tidbits of information; the bad is that it can be harder to study for a test like this that covers more abstract forms of knowledge. (More on how to manage this in the "How to Review" section!)

The AP Bio exam and curriculum as a whole will be centered around your understanding of what the College Board refers to as its four "Big Ideas," each of which covers several different topics.

Your success on the AP Bio exam ultimately rests on your being able to connect specific concepts with the overarching Big Ideas that define the course.

So what are these Big Ideas exactly?


Big Idea 1: Evolution

Main Point: The process of evolution drives the diversity and unity of life

Topics Covered:

  • Natural selection
  • Hardy-Weinberg
  • Biodiversity and categorization of organisms


body_darwin.jpgCharles Darwin married his first cousin. You'd think he would know better.


Big Idea 2: Energetics

Main Point: Biological systems use energy and molecular building blocks to grow, reproduce, and maintain dynamic homeostasis

Topics Covered:

  • Molecular biology
  • Biological systems and reactions
  • Photosynthesis
  • Cellular respiration
  • Cell structure
  • Cell membrane properties (diffusion and osmosis, proteins)
  • Thermodynamics/homeostasis
  • Immune response


body_sunflower.jpgPhotosynthesis is way more elegant than eating. Then again, flowers will never taste ice cream, so I kinda feel sorry for them.


Big Idea 3: Information Storage and Transmission

Main Point: Living systems store, retrieve, transmit, and respond to information essential to life processes

Topics Covered:

  • Genes and gene mutations
  • Cell cycle (mitosis, meiosis) and cell communication
  • Mendel and laws of inheritance
  • Viruses
  • Endocrine system
  • Nervous system


body_dna.jpgDeoxyribonucleic acid: It's DNAmazing!™


Big Idea 4: Systems Interactions

Main Point: Biological systems interact, and these systems and their interactions exhibit complex properties

Topics Covered:

  • Enzymes
  • Plant structure and systems
  • Circulatory system
  • Digestive system
  • Musculoskeletal system
  • Ecological principles



Fun digestive system fact: if you eat a watermelon seed, a watermelon will grow inside your stomach. The ideal climate for watermelon growth is 96 degrees and highly acidic.


The Importance of Labs

Apart from background knowledge of all this content, it's important to understand your labs and the basic underlying principles that govern scientific experiments. If you know the ins and outs of experimental design, you'll earn a lot of points on the AP Bio exam.

Important lab topics include the following:

  • Artificial Selection
  • Modeling Evolution
  • Comparing DNA Sequences
  • Diffusion and Osmosis
  • Photosynthesis
  • Cellular Respiration
  • Mitosis and Meiosis
  • Bacterial Transformation
  • Restriction Enzyme Analysis of DNA
  • Energy Dynamics
  • Transpiration
  • Animal Behavior
  • Enzyme Catalysis


body_microscope.jpgMicroscopes show us that the world around us is far creepier and grosser than we ever imagined.


AP Biology Review Preview: 4 Key Tips to Keep in Mind

In this section, I'll give you some preliminary study tips that will help you get the most out of your AP Biology review time.


Tip 1: Plan Out Your Time

First of all, you should think about how much time you have left before the AP test. This will affect the structure of your study plan. If you're taking other AP classes or have a lot of personal commitments in general, you might want to start earlier depending on your confidence with the material.

Consider your schedule and the time you're willing to spend on AP Biology. Since there's so much content in this course, I think 20 hours of studying is a reasonable goal. However, if you find that you're already scoring at a high level (a high 4 or anywhere in the 5 range), you might aim for just 10 hours or so.

You should balance your time relatively evenly between studying the material and taking practice tests. In AP Bio, you might benefit from devoting a bit more time to practice testing.

Since the test is now more targeted toward assessing analytical skills, practicing real test questions might help you more than just memorizing content (although both are still important!). I'll give you more information about how to use practice tests and review materials effectively in a moment.


Tip 2: Use Appropriate Review Materials

The importance of using the right review materials can't be overstated, especially in the case of AP Biology. With the recent changes to the test, it's critical that you don't use old study materials and assume that they'll give you all the tools you need to succeed on the new format.

Unfortunately, because the newest version of the AP Biology exam only began being administered in 2020, there aren't that many review books available for it.

Still, because not much actually changed in terms of content between the 2013-2019 version of the test and the current version, it's OK to use books that target the 2013-2019 AP Biology exam. Just remember that you don't need to do any grid-in questions and can skip over three multiple-choice questions. In addition, you should do only four of the six short-answer questions.

Some review books students have found the most useful include CliffsNotes' AP Biology, 5th Edition for content review and Sterling's AP Biology Practice Questions for practice questions that give you a good sense of what the test is like.

Pearson's Preparing for the Biology AP Exam also has a solid number of positive reviews and might be a decent source of practice free-response questions.

Avoid using practice questions that come from exams before the 2013 test, when some of the more drastic changes were implemented. You might still be able to use older questions to refresh your memory on certain topics, but they won't really prepare you for the more analytical framework of questions on the current AP Biology test.

Furthermore, the College Board now offers a great online resource called AP Classroom, through which students can interact with teachers, complete homework and get feedback on assignments, and receive access to review materials for the AP Bio test, including real practice questions. You'll use your College Board student account login credentials to access AP Classroom, and once logged in, you can access a different section for each AP class you're taking.


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Tip 3: Memorization Isn't Enough

Even though AP Biology still involves a fair amount of memorization, you can't focus exclusively on content knowledge and just assume you'll do great on the test.

AP Bio questions will test your critical-thinking skills and logical reasoning abilities, along with your general knowledge of biology. That's why it's so important that you spend a significant amount of time doing practice questions in addition to content review. Don't let the test surprise you!


Tip 4: Don't Forget About Labs

Revisiting old labs is not super fun (well, it wasn't for me), so you might be tempted to ignore them and just focus on studying content outside the lab context.

Try to avoid this temptation! Go through your labs, and make sure that you understand their methodologies and the reasoning behind the results. Understanding the scientific method and the components of a good experiment is key to acing the AP Bio exam.

The more lab review you do, the more comfortable you'll feel during the test.


body_flask.pngRemember the lab where you melted down entire trees into a mysterious green serum? No? Well then, you better get studying!


How to Review for the AP Biology Exam: 5-Step Guide

As you study for the exam, follow the five steps below to ensure your AP Bio review is as thorough and effective as possible.


Step 1: Take a Diagnostic Test

The first step of your AP Biology review is to take a practice exam so you can see how much you'll need to study and which areas need the most work.

You should take your first complete practice test no later than the beginning of your second semester. You can use a practice exam from a review book or search online for a practice test. The review books I mentioned in the previous section have some useful materials.

When you take a practice test, make sure it's the newest 2020 version of the exam (or, if you can't find this, at least a version from 2013-2019). If you see practice tests that have 100 multiple-choice questions in the first section, you're looking at a very old version of the AP Bio exam! You won't be able to rely on your scores on this version to get a clear picture of where you fall on the new test.


Step 2: Calculate Your Score and Set a Goal

Once you've taken a diagnostic test, you can calculate your score on the 1-5 AP scale. According to the CliffsNotes review book mentioned above, you can estimate your score using the following method:

  • Multiply the number of questions you answered correctly in Section 1 by 0.725
  • Multiply the number of points you earned in Section 2 by 1.25
  • Add those two numbers together to get your raw score

Then, convert the raw score to an AP score using the following chart:

Raw Composite Score

AP Score

60-100 5
50-59 4
41-49 3
33-40 2
0-32 1


For example, if you got 42 questions correct on the multiple-choice section and earned 25 points on the free-response section, your raw score would be (42 * .725) + (25 * 1.25) = 61.7 = just barely made it into the 5 category!

This is without taking the curve into account, which is different every year, but it should give you a rough idea of where you stand. Unless you're scoring a really high 5 (90+), you should still put in a bit of study time to make sure you're fully prepared.

If you score low (1 or 2), you might make it your goal to raise your score to 3. Just keep in mind that some schools don't accept 3s for college credit, so you might want to aim higher after you make it to this first milestone.

Most colleges consider 4 to be the standard cutoff for AP credit, so you should try for at least a 4 if you're hoping to get a head start in college. Once you're consistently scoring in the 3 range on this exam, you can set 4 or 5 as your goal.

Even if you're already at the 4 or 5 level on AP Biology, you probably still have some room to improve. It's nice to get in some extra practice so that you feel very comfortable on the real test.

Depending on how much you need to improve and on how long you want to spread out your prep, you might come up with different plans. To improve by 1 AP score point, you can get away with studying only two months or so in advance. On the other hand, if you're hoping to improve by 2 or more points, try to start midway through the school year to avoid cramming.


body_confidence-1.jpgConfidence is key. If you need to wear a business suit to the test to make yourself feel in control, go for it (I am not responsible for the relentless mocking you will endure from your peers).


Step 3: Analyze Your Mistakes

This is the most critical part of the review process, and it's particularly important for AP Biology. There's a lot of material to learn, and you don't want to waste any time going over concepts you already have down.

Comb through your mistakes on the diagnostic test to see where the most errors happened and why. Did your mistakes center more around lack of knowledge of background information or difficulty analyzing the scenarios presented on the test (in other words, you knew the information but couldn't answer the question because it confused you)?

You'll most likely have a little of each type of mistake, but if one is more prevalent than the other, take that into account for your studying strategy. For example, it wouldn't be a good idea to keep drilling basic content knowledge if most of your mistakes were due to your misinterpreting complex questions or reading diagrams incorrectly. You'd want to devote less of your time to reviewing biological terms and more to doing realistic practice questions.

Even in those cases, you'll probably still have at least a few issues with content knowledge. As you go through your mistakes, keep a running list of the ideas you need to revisit in your notes or review book. If you're caught off guard by your unfamiliarity with a certain topic, you should pay special attention to that topic in your prep.

You might also notice mistakes due to carelessness or time pressure that aren't directly related to your knowledge of the material or understanding of the question. In this case, you'll need to think about revising your basic test-taking strategies. I'll go into more detail on this next.


body_detective-1.pngDo some practice test detective work! I think this is a detective. Either that or a random guy smoking a pipe and trying to figure out how bad the pimple on his nose looks.


Step 4: Fix Your Mistakes

There are a few things you can do to revise your strategies for taking the exam and effectively review concepts you didn't understand.

The obvious first step is to go back into your textbook, your notes, or a reliable AP Bio review book (or even all three!) and brush up on the information you forgot. Sometimes for biology, this can be a little overwhelming due to the complexity of the material.

If you're trying to understand systems or processes, I recommend testing yourself by drawing diagrams of how they work. This will allow you to make connections between dry facts presented in the text and the biological reality of what's happening in the system. It will help you not only in your content knowledge but also in your ability to analyze related scenarios on the test. You can use this strategy for many concepts in AP Biology, and it will make them much simpler to understand.

To correct your other mistakes that have more to do with question comprehension, you'll need to focus on doing similar practice questions. I suggest getting Sterling's AP Biology Practice Questions for some questions that are organized logically by topic area and well aligned with the new exam format.

More practice is also a good remedy for careless errors and time-management problems. You can learn how to better identify the key parts of each question and avoid distractions that might throw you off.

Underlining the most important parts of the question can be a good strategy if you're prone to careless errors. If time management is a problem, put some thought into why you might've run out of time. Did you linger for too long on difficult questions? Remember that it's a smart idea to skip questions that are giving you a lot of trouble (meaning, they're not answerable within a minute) and come back to them later once you've gotten through the whole section.


body_practice-10.jpgPractice makes perfect. Maybe you can compose an AP Biology song to help you remember stuff. "Now enzymes ... BREAK IT DOWN!"


Step 5: Take Another Test and Repeat Previous Steps

Now that you've analyzed and fixed your mistakes on the diagnostic test and done more targeted studying, it's time to take another practice test.

Score this new test and then repeat steps 3 and 4. You should notice improvements as you continue to repeat this process and gain familiarity with the format and content of the AP Biology exam.

If you don't notice positive changes from one test to the next, it might be time to reevaluate your review techniques. Depending on how early you start studying for the AP Bio test and how much you want to improve, you might go through these steps once, twice, or seven times.

Continue the process until you achieve your score goals or run out of study time!


Conclusion: AP Biology Review Guide

The AP Biology test is a long exam, and it covers a wide range of material.

Recently, the test was updated to focus less on information recall and more on analytical thinking, which can be good and bad. On the one hand, you won't have to rely on memorization as much. On the other, your AP score will be highly dependent on your ability to think through complicated scenarios presented on the test.

In addition, the test underwent some structural changes in 2020. These key changes included going from 69 questions on the multiple-choice section to just 60 questions and reducing the number of short-answer questions from six to four. There will also no longer be any grid-in questions.

In your own AP Biology review, you should go over all the information you learned in the course. However, you should also devote a significant amount of your time to practice testing so that you can learn to think in the way the test wants you to think.

If you plan your study time wisely and learn how to solve the types of questions that are most difficult for you, you'll be on your way to a great AP Bio score!


What's Next?

Ready to jump into reviewing biology concepts? We have guides to help you review cell theory, enzymes, and homologous and analogous structures, as well as quick looks at parts of the cell (cell membrane and endoplasmic reticulum) and the photosynthesis equation.

Wondering exactly how much time you have before your AP tests? Here are the AP test dates and times for 2021.

Considering an AP Calculus course? Read this article for some guidance on deciding whether you should take AP Calculus AB or BC.


One of the single most important parts of your college application is what classes you choose to take in high school (in conjunction with how well you do in those classes). Our team of PrepScholar admissions experts have compiled their knowledge into this single guide to planning out your high school course schedule. We'll advise you on how to balance your schedule between regular and honors/AP/IB courses, how to choose your extracurriculars, and what classes you can't afford not to take.

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Samantha Lindsay
About the Author

Samantha is a blog content writer for PrepScholar. Her goal is to help students adopt a less stressful view of standardized testing and other academic challenges through her articles. Samantha is also passionate about art and graduated with honors from Dartmouth College as a Studio Art major in 2014. In high school, she earned a 2400 on the SAT, 5's on all seven of her AP tests, and was named a National Merit Scholar.

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