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The Expert's Guide to the AP Biology Exam

Posted by Samantha Lindsay | May 26, 2019 7:00:00 PM

Advanced Placement (AP)



If you're taking AP Biology, it's a good idea to familiarize yourself with the exam before you get too far into the course. Preparing ahead of time for the AP exam format and fully understanding which concepts are covered on the AP Biology test can go a long way toward earning a high score (and potentially getting college credit!).

This article will take you through the structure and scoring of the AP Bio exam and give you some key tips on the best ways to study for AP Biology.


How Is the AP Biology Exam Structured?

The AP Biology test has a multiple-choice section (that also includes grid-in questions, so it’s not purely multiple choice) and a free-response section. It is three hours long in total.

The next AP Biology exam will take place on Monday, May 11, 2020, at 8 am.


Multiple-Choice Section

The first section on AP Bio consists of multiple-choice questions and a handful of grid-in questions. Here's an overview of what to expect:

  • 63 multiple-choice questions
  • Six grid-in questions
  • 90 minutes long
  • Worth 50% of your score

Grid-in questions ask you to integrate math and science skills to make calculations and then enter your answer into a grid on the answer sheet (essentially, these are short-response questions that are similar to grid-in questions on the SAT Math section).


Free-Response Section

The second section is the free-response section, which looks like this:

  • Six short-response questions
  • Two long-response questions
  • 90 minutes long (including a 10-minute reading period)
  • Worth 50% of your score (25% for the short responses and 25% for the long responses)

One of the long-response questions will be lab- or data-based, while all short-response questions require you to write at least a paragraph for your response or argument.


Expectations of the AP Biology Exam

Here's what both sections on the AP Biology test expect you to know how to do:

  • Understand how graphical and mathematical models can be used to explain biological principles and concepts
  • Make predictions and justify events based on biological principles
  • Implement your knowledge of proper experimental design
  • Interpret data


body_monday.jpgIs this coffee smiling at me? Or am I delirious from lack of sleep?


What's Tested on the AP Biology Exam? 4 Big Ideas

The AP Biology test doesn't include a set number of questions that deal with each topic area, but you should note that the exam is centered around four major themes (or "Big Ideas," as the College Board calls them). Here's a list of these themes, followed by the topics that fall beneath each of them:


Big Idea 1: The Process of Evolution Drives the Diversity and Unity of Life

Topics that fall into this category include the following:

  • Natural selection
  • Mathematical modeling of populations
  • Species classification
  • Biodiversity


Big Idea 2: Biological Systems Utilize Free Energy and Molecular Building Blocks to Grow, to Reproduce, and to Maintain Dynamic Homeostasis

Topics that fall into this category include the following:

  • Molecular biology
  • Cell structure
  • Photosynthesis
  • Cellular respiration
  • Thermodynamics and homeostasis
  • The immune response


Big Idea 3: Living Systems Store, Retrieve, Transmit, and Respond to Info That's Essential to Life Processes

Here are the main topics in this category:

  • Genetics
  • The cell cycle (mitosis and meiosis)
  • Viruses
  • Communication between cells
  • The endocrine system
  • The nervous system


Big Idea 4: Biological Systems Interact, and These Systems and Their Interactions Have Complex Properties

The topics that fall into this category include the following:

  • Plant structure
  • Enzymes
  • The circulatory system
  • Digestion
  • The musculoskeletal system
  • Ecology


AP Biology Sample Questions

Now that you have a basic content outline, here are some examples of the types of questions you'll see on the AP Biology test so that you can get an even better idea of what to expect.



Here is an example of a multiple-choice AP Biology exam question:


This question looks kind of complicated, but let’s break it down. The first sentence is background information that isn’t really necessary for answering the question, besides the fact that it tells us we’re talking about sickle cell anemia. This is helpful if you can remember basic facts about the disease that you can use to contextualize the question.

The main part of the question asks what will be affected when you replace a hydrophilic amino acid with a hydrophobic one on a hemoglobin protein. Based on your knowledge of sickle cell anemia and molecular properties, you should be able to eliminate choices B and C, which don’t have much to do with the abnormality described in the question.

Choice D can also be eliminated because the internal secondary structure of the protein is not altered by the existence of the hydrophobic group.

This would only affect how the molecule interacts externally with other hemoglobin molecules, as in choice A (the correct answer).



Here’s an example of a grid-in question that you might see on the AP Biology test:


This question just asks you to read a graph and perform some basic calculations. We can see from the graph that from day 3 to day 5, the population size grew from 200 to 900 individuals. This means that it increased by 700 individuals in total.

If we divide 700 by the time period of two days, that's a mean growth rate of 350 individuals per day. Therefore, you would enter “350” into the grid for this question.



Bacteria gettin' it on.


Short Free Response

Here’s an example of a short free-response question you might see on the AP Biology test:

On this particular question, you could earn a maximum of 4 points (one for each type of data you describe in part a and one for the explanation for each in part b). Here are three types of data and their corresponding explanations you could cite for points:

Option 1

Data Description: The ability of the plants to produce viable seeds/offspring in nature

Explanation: This is consistent with the definition of a biological species

Option 2

Data Description: Comparison of the two plants’ DNA sequences or structures of other conserved molecules.

Explanation: Sufficient similarity between the DNA structures would support the existence of a single species

Option 3

Data Description: Discovering the existence of fertile hybrid plant populations living between the two other populations of plants

Explanation: This is also consistent with the definition of a biological species (again, ability to produce fertile offspring)


body_mountainplants.jpgThere must be jobs out there for which you just have to collect plant samples. Start building your experience now by never showering.


Long Free Response

Here’s an example of a long free-response question you might see on the AP Biology exam:

On this question, you could earn up to 10 points in total.

Part A is worth 3 points. To earn these points, you have to:

  • Create a graph that is correctly labeled, is correctly scaled, and uses proper units.
  • Make it a bar graph with correctly plotted sample means.
  • Show the standard error (+/- 2) on your graph above and below the means.
Part B is worth 2 points. To earn these points, you have to:
  • Identify populations I and III as the most likely to have statistically significant differences in the mean densities.
  • Explain why this is the case (because the margins of error do not overlap for the mean densities of these two populations; 9+2 is less than 14-2).
Part C is worth 5 points:
  • You'd earn 2 points for identifying the independent variable (presence of herbivores) and dependent variable (trichome density).
  • You would earn 1 point for identifying a control treatment (absence of herbivores).
  • You would earn 1 point for identifying an appropriate duration of the experiment (more than one generation of plants).
  • The final point would be earned by predicting experimental results that would support the hypothesis (higher trichome density under the experimental conditions as compared to the control conditions).


body_koalas.jpgUgh, gross! This leaf is full of trichomes.


How Is the AP Biology Exam Scored?

As mentioned, on AP Bio the multiple-choice section (including the grid-ins) makes up 50% of your score, and the free-response section makes up the other 50%.

For the multiple-choice section, it’s easy to calculate your raw score: you just get 1 point for each question you answer correctly. There are no point deductions for incorrect or blank answers. This is also true for the grid-in questions.

Scoring is a bit more complicated on the free-response section (which is scored by actual graders rather than a computer). Each of the six short response questions has a different point value depending on its complexity. Three are scored out of 3 points, while the other three are scored out of 4 points. Finally, each long free-response question uses a 10-point scale.

To figure out your final AP Bio score, you’ll need to do a couple more calculations. This can change from year to year based on the performance of students, but this is the most recent estimate I have regarding the methodology behind it:
  1. Multiply the number of points you got on the multiple-choice section by 1.03
  2. Multiply the number of points you got on the two long free-response questions by 1.5
  3. Multiply the number of points you got on the short free-response questions by 1.43
  4. Add all these numbers together to get your raw AP Biology score

Here's a conversion chart you can use to see how raw score ranges (generally) translate into final AP scores (on a scale of 1-5). I've also included the percentage of students who earned each score in 2017 to give you an idea of what the score distribution looks like:

Raw Score

AP Score

% of Test Takers Earning Score (2017)
















For example, if you got 40 points on the multiple-choice section, 13 points on the long-response questions, and 14 points on the short-response questions, your AP Bio score would be (40*1.03) + (13*1.5) + (14*1.43) = 80.72. This indicates that you'd likely earn a 4 on the AP Biology test.


body_calculator-4.jpgIf you want to spice things up a little bit, you can even do the math on a snazzy calculator with red buttons! Isn't this fun?!?!?


What’s the Best Way to Prep for the AP Biology Exam?

Now that you know all about what's on the AP Biology test, it's time to learn how to ace it. Follow these four tips so you can get a great score!


Tip 1: Review Your Labs

Labs make up about 25% of the AP Biology course, and for good reason. It’s important to understand how labs are conducted and how the principles behind them relate to the main ideas of the course. This will help in answering both free-response and multiple-choice questions that deal with lab scenarios on the test.

Many free-response questions ask you to identify the components of a proposed experiment (dependent and independent variables) or to design a lab to test a certain hypothesis. You might have forgotten about the labs you did toward the beginning of the year, so take extra care to go over them. Make sure that you understand exactly how they were conducted and what the results mean.


Tip 2: Learn to Connect Small-Scale Terms With Large-Scale Themes

The AP Biology test covers four major themes:

  • Evolution
  • Energy use in biological systems
  • Processing of stimuli in biological systems
  • Interaction of biological systems

Under each of these umbrella topics are many terms and ideas you'll need to review.

Memorization can be a big part of studying for AP Biology. However, memorizing the definitions of terms will only get you so far. You'll also need to understand how they relate to one another and to the four themes listed above.

The exam emphasizes making connections between biological terms, corresponding biological systems, inputs and outputs of these systems, and the overall impact on living organisms and the environment. You should be able to follow a chain of reasoning from the specific to the broad, and vice versa.


body_oak.jpgIf this tree is AP Biology, the four big branches are the four themes, and all the smaller offshoots are different terms and concepts. For it to survive, there has to be a lot of communication between the trunk and the rest of the tree!


Tip 3: Practice Eliminating Irrelevant Information

Both multiple-choice and free-response AP Biology questions include lots of scientific terminology and visual aids, and this kind of format might be intimidating if you’re not used to it. It’s important to practice sorting through this jumble of information so that you can quickly get to the root of the question rather than obsessing over small details you don’t understand.

Try underlining important words and phrases in the question to help you stay focused on the main points and avoid misleading distractions.

You should also practice responding to free-response questions in a straightforward way without any unnecessary fluff. Remember, this isn’t an English test; the graders are just looking for clear facts and analysis. Make it easy for them to give you points!


Tip 4: Learn Good Time Management

The AP Bio exam is pretty long (even for an AP test), and many of the questions require quite a bit of thought. You need to ensure that you have a good handle on time management before exam day. The best way to do this is to take at least one AP Biology practice test.

There are 69 questions in total on the multiple-choice section, and you have 90 minutes to answer them. This comes out to about one minute and 15 seconds for each question.

Based on that fact, you should spend no more than a minute on each multiple-choice question the first time you go through a practice test. If you find yourself spending extra time on a question, skip it and come back to it later. It’s best to give yourself some leeway in case you run into trouble on the grid-in questions.

You also have 90 minutes for the free-response section, but you'll spend different amounts of time on the long and short questions. Limit your time on the long questions to 22 minutes each or less (44 minutes total), and your time on the short questions to six minutes each or less. If you can’t work this fast right away, try doing additional practice free-response questions until you feel comfortable with the time constraints.


body_champagne.jpgReally get to know the test. Take it on a romantic getaway, and watch the sunset with it. Deep down, the AP Biology exam just wants to be understood.


Summary: How to Do Well on the AP Biology Exam

The AP Biology exam is three hours long, with two sections that take up an hour and a half each. The multiple-choice section has 69 questions in total, while the free-response section has eight questions in total.

The content of the exam spans four major themes, or Big Ideas, that are central to the course. These include the following:

  • Evolution
  • Energy use within biological systems
  • The processing of stimuli within biological systems
  • Interactions that occur between biological systems on a larger scale in nature

Questions ask you to connect specific terms and concepts to these central topics. They'll test your ability to interpret data, to make predictions and inferences based on biological evidence, and to analyze different experimental scenarios.

Overall, AP Biology is a tough test, but as long as you study hard and know what to expect, you're perfectly capable of getting a great score!


What's Next?

Review key biology ideas and facts with our subject-focused guides. You'll learn about cell theory and the functions of the cell membrane and endoplasmic reticulum, what the distinction is between homologous and analogous structures, how enzymes work, and when and how to use the photosynthesis equation.

If any of your prospective colleges require or recommend Subject Test scores, you might want to take the Biology SAT Subject Test in addition to the AP Biology test. Read this article to learn more about the differences between AP tests and Subject Tests, and which ones matter the most.

Still planning out your class schedule? Find out how many AP classes you should take in high school based on your college goals.

The difficulty level of different AP classes might play a role in your decision whether or not to take them. Check out these articles for more info on which AP classes are the hardest and which are the easiest.


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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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