AP Biology Vs. AP Chemistry

Do you need help finding best-fit colleges or writing essays? You can sign up for a free consult here.

Advanced Placement classes are vitally important to your high school career. With over three dozen to choose from, it can be difficult to decide which classes to take and how to order them. In this series of articles, we’ll cover a broad selection of AP courses to help you make an informed decision on which ones are right for you. 

Today we’re looking at two courses: AP Biology and AP Chemistry. These challenging courses lay the groundwork for students who plan to study science in college and beyond. Today’s post will cover content, exams, difficulty level, and other factors to consider when deciding which courses to take and when. Let’s get started. 

AP Biology

In this course, you’ll learn a number of basic skills that apply to all types of science in addition to learning the foundations of biology. The course focuses on four big ideas: evolution, energetics, systems interactions, and information storage and transmission.

What does the class include?

AP Biology takes students through the basics of living systems, beginning at a cellular level and working its way up to ecological systems. The class and exam are ordered in two ways: basic Science Practices and skills, which we’ll go into below, and the course content. The course is organized into eight units of study:

Unit 1 – Chemistry of Life

This unit focuses on the chemical processes of cells at a molecular level.

Unit 2 – Cell Structure and Function

This unit takes a broader look at the cell membrane, organelles, and cellular products.

Unit 3 – Cellular Energetics

Students then continue their study of cells by learning about photosynthesis and cellular respiration.

Unit 4 – Cell Communication and Cell Cycle

In this unit, students explore how cells communicate and replicate.

Unit 5 – Heredity

This unit deals with the storage and transmission of information from one generation to the next.

Unit 6 – Gene Expression and Regulation

This unit delves deeper into genetics, DNA, RNA, and gene expression. 

Unit 7 – Natural Selection

The penultimate unit focuses on the drivers of evolution and their relation to larger systems.

Unit 8 – Ecology

The final unit covers interconnected biological systems.

You can find a sample syllabus here.

What grade is it typically taken in?

The course sequence for science classes in many high schools is Biology followed by Chemistry followed by Physics. Since many high schools require biology as a prerequisite to AP Bio, students may take the AP course in their sophomore year. This leaves subsequent years free for chemistry and physics. 

Schools vary, and many students take AP Biology their junior or senior year. 

Who should take AP Biology?

AP Biology is an excellent choice for any student looking to take on a challenging course load and develop a competitive college application. Students will learn these key skills:

  • Designing experiments to test a prediction or theory
  • Collecting and analyzing data
  • Interpreting data to draw conclusions
  • Developing and supporting a scientific claim with evidence

We strongly recommend this course to students interested in pursuing any variety of science degree, including but not limited to a degree in Biology, Ecology, or Zoology. It’s a basic, foundational course that will serve you well regardless of your field of study. 

Even if you don’t plan on majoring in science, this course helps to show that your academic interests and aptitude are well rounded. That being said, it’s better to score well on a few AP tests than to have middling or low scores on a greater number. Be realistic about how many AP courses you can handle at one time and what your academic strengths are.

How hard is the exam? 

Biology is one of the easier AP exams. The passing rate in 2021 was 59.2%, which is about average for these exams. In 2022 it was even higher: 67.9%. Bear in mind that AP Biology is one of the more popular AP courses, with over 200,000 students taking it each year; exams with higher pass rates generally have a smaller number of dedicated students taking the exam.

AP exams are given in May over a two-week period. They are graded on a scale of one to five:

5 – Extremely well qualified, 4 – Well qualified, 3 – Qualified, 2 – Possibly qualified, 1 – No recommendation. Some schools will give college credit for a score of 3 or higher, while others will only give credit to students who scored 4 or 5 on the exams.

The exam focuses on six key Science Practices that students learn and use throughout their AP Biology class. Here are the six practices and the weight they’re given on the exam:

Skill Description Exam Weighting (Multiple-Choice Section)
1. Concept Explanation Explain biological concepts, processes, and models presented in written format 25%–33%
2. Visual Representations Analyze visual representations of biological concepts and processes 16%–24%
3. Question and Method Determine scientific question and method 8%–14%
4. Representing and Describing Data Represent and describe data 8%–14%
5. Statistical Tests and Data Analysis Perform statistical tests and mathematical calculations to analyze and interpret data 8%–14%
6. Argumentation Develop and justify scientific arguments using evidence 20%–26%

In the first section, you’ll have 90 minutes to answer 60 multiple-choice questions. In the second section, you’ll have 90 minutes to answer six free-response questions. You can find more information here.

How to Study for AP Biology

Preparing for AP exams begins on your first day of class and continues through the year. You’ll need to take detailed notes and engage with all of the course materials consistently to become comfortable with the many skills and concepts that these classes cover. Review frequently throughout the year to avoid cramming at year’s end or showing up to the exams ill prepared. 

AP Biology covers a ton of material and you’ll need to memorize a lot of new terms and concepts to do well on the exam. If you need extra help, try AP Biology Premium Prep, Barron’s AP Biology Premium or AP Biology Crash Course.

As you approach the exam, it’s wise to take some practice tests. Remember, taking a practice test is only the first step. After that, you’ll need to review your mistakes, study the topics you were unable to answer correctly, and then take a second practice test. Repeat this as many times as needed.

Get personalized advice!

We've helped thousands of students choose a career and guided them along it to success. Here is what our clients say about us:

"Transizion guided and advised my daughter through her essays for great schools, including NYU, UC Berkeley, USC, GW, and Northwestern. My daughter was independent throughout the process and really enjoyed all the feedback and guidance they gave her. They were always available to answer all of our questions rapidly. They made my life much easier especially since my daughter was a Canadian student and the whole application to US schools was very foreign to our family. I highly recommend Transizion for their professionalism and work ethics!"

AP Chemistry

AP Chemistry is an introductory college-level chemistry course.

What does the class include?

AP Chemistry is organized into nine units of study:

  • Unit 1: Atomic Structure and Properties
  • Unit 2: Molecular and Ionic Compound Structure and Properties
  • Unit 3: Intermolecular Forces and Properties
  • Unit 4: Chemical Reactions
  • Unit 5: Kinetics
  • Unit 6: Thermodynamics
  • Unit 7: Equilibrium
  • Unit 8: Acids and Bases
  • Unit 9: Applications of Thermodynamics

You can find detailed information here.

What grade is it typically taken in?

AP Chemistry is a challenging course typically taken in junior or senior year. 

Who should take AP Chemistry?

AP Chemistry is a good choice for any student who is passionate about science and performs well in STEM classes. 

We strongly recommend this course to students interested in one of the following majors:

  • Agricultural Engineering
  • Animal Sciences
  • Astronomy
  • Biology
  • Botany
  • Chemical Engineering
  • Chemistry
  • Computer Software Engineering
  • Electrical Engineering
  • Environmental Engineering
  • Environmental Science
  • Food Science
  • Forensic Science
  • Forestry
  • Genetics
  • Geology
  • Industrial Engineering
  • Marine Biology
  • Marine Sciences
  • Materials Engineering
  • Mechanical Engineering
  • Molecular Biology
  • Neuroscience
  • Nuclear Engineering
  • Nursing 
  • Nutrition Sciences
  • Psychology
  • Public Health
  • Soil Science
  • Zoology

If you’re interested in pursuing a career in science, including medicine, we recommend taking both AP Biology and AP Chemistry in high school. 

How hard is the exam? 

This is one of the more difficult AP exams, with a pass rate of 53.9% in 2022.

The Chemistry course and exam is organized around six Science Practices:

Skill Description Exam Weighting (Multiple-Choice Section) Exam Weighting (Free-Response Section)
1. Models and Representations Describe models and representations, including across scales. 8%–12% 2%–4%
2. Question and Method Determine scientific questions and methods. 8%–12% 10%–16%
3. Representing Data and Phenomena Create representations or models of chemical phenomena. Not assessed in multiple-choice section. 8%–16%
4. Model Analysis Analyze and interpret models and representations on a single scale or across multiple scales. 23%–30% 5%–9%
5. Mathematical Routines Solve problems using mathematical relationships. 35%–42% 43%–53%
6. Argumentation Develop an explanation or scientific argument. 8%–12% 15%–24%

In the first section, you’ll have 90 minutes to answer 60 multiple-choice questions. In the second section, you’ll have 105 minutes to answer 7 free-response questions. Each section weighs equally towards your final score. 

How to Study for AP Chemistry

Get real friendly with the periodic table and review, review, review. 

Your best bet is to start early with practice tests, identify areas of weakness, and do enough practice problems (with help if necessary) to master each one. Try a book like Barron’s AP Chemistry Premium or The Princeton Review’s AP Chemistry Premium Prep. You can also find previous years’ free-response questions online.

In the days before the exam, give yourself some time to breathe and get plenty of sleep. AP exams do not penalize test takers for wrong answers. So if you’re unsure, don’t skip the question! Take your best guess and move on, coming back around to review at the end if you have time. 

Starting with the 2022-23 school year (spring 2023 exam), a scientific or graphing calculator is recommended for both sections of the exam. 

Click here for more advice on studying for AP exams. 


AP courses are a vital part of your high school career, and these two courses can help solidify college applications for students who want to go to competitive universities, particularly for prospective science majors. Both classes are challenging, but AP is a good option even for students who are unsure of what they want to major in. 

Here are the 2022 score distributions for the two exams:

Exam 5 4 3 2 1
AP Biology 15.0% 23.1% 29.7% 21.6% 10.5%
AP Chemistry 12.5% 17.0% 24.5% 23.6% 22.5%

As you can see, AP Biology has a significantly higher pass rate, and students are more likely to score high enough to earn college credit with this course. AP Chemistry is the more difficult exam, making it a better choice for students who have already taken AP science courses and intend to pursue a degree in a related field. 

If you’re still not sure whether these classes are the right choice for you, talk to students who have taken one or both at your school. Often the teacher can make or break your experience of any given course, so that’s always an important aspect to consider.

Stay tuned for more articles on other Advanced Placement courses. And please reach out if you need help planning your course schedule, understanding advanced concepts, or studying for your exams. Our experienced tutors can help you prepare for your exams and decide which AP classes to take next year.

Learn how we can help you with college and career guidance! Check out our YouTube channel!

Click Here to Schedule a Free Consult!