AP® Biology Course and Exam Description

AP Biology is one of the most popular courses within the gamut of AP courses. It covers fundamental concepts in Biology at the foundational level and teaches students critical thinking through core science practices. While the course may be vast and challenging, you will be able to build a strong foundation in Biology, which can set you up for success at the college level.

Understanding what to expect as a student of AP Biology is the first step to a good score. In this AP Biology course and exam description, we’ll take a look at the AP Biology course outline as well as the weightage of each unit in the final exam so you can be best prepared. We’ll also identify AP Biology’s key concepts and what you’ll learn from each of them. Let’s dive right in!

AP Biology Units, Topics, and Key Concepts

In order to understand what you will learn in this course, it’s essential to know the outline of the course itself. It will help you identify if you are ready to take AP Biology.

The course is made up of two primary sections — Science Practices and Course Content. As you progress through the course, you will learn essential science practices through the course content or lessons, so the two are intertwined from the very beginning and both are equally important for building a solid foundation in biology.

The course content is broken down into units, which are further broken down into smaller topics to make learning easy. Each of these units is based on the 4 Big Ideas, known as the essential biological concepts critical to a strong foundation in biology. The exam itself is made up of 60 multiple choice questions (MCQs) and 6 free-response questions (FRQs) from these units with varying weightages. You can read more about the exam format from our AP Biology Exam Format.

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What Are the AP Biology Science Practices?

Science Practices are skills vital to the study and practice of biology. They promote critical thinking and analysis, which are necessary for further studies in biology and are also key to doing well on the exam. You will be expected to develop and master these skills throughout the AP Biology course. In addition, each unit within the course will encourage learning a particular set of science practices.

There are six science practices in AP Biology that you will master by the end of the course. Below is a detailed list of these science practices and the skills they will teach you.

  1. Concept Explanation
    This science practice aims at developing your ability to explain concepts, models, and processes of biology that can be seen in written format.

    Skills you will learn:

    • Describe biological concepts and processes – Describe traits, characteristics, elements, etc., in a particular concept and describe structures and functions within a process.
    • Explain biological concepts and processes – Explain concepts, steps of a process, the relationship between structures and their functions, and trends in a system.
    • Explain applied biological models, concepts, and processes in a particular context – Explain how biological models, concepts, and processes apply in the real world.
  2. Visual Representations

    Visual representations are an essential tool in biology, especially when learning and exploring new concepts. This science practice will teach you how to create, use, and analyze visual representations.

    Skills you will learn:

    • Describe visually represented concepts, processes, and models – Describe characteristics, patterns, and trends.
    • Explain relationships between characteristics in visually represented concepts, processes, and models – Explain concepts and compare and predict patterns/trends in a representation.
    • Correlate concepts and processes in a representation to principles and theories in biology – Develop conclusions based on the concepts in a representation.
    • Showcase relationships in a biological model – Representation of relationships using mathematical models, diagrams, and flowcharts.
  3. Questions and Methods

    Questioning natural phenomena is a critical scientific practice that will help further your understanding of biological concepts. You will learn to identify possible errors in experiments or data sets and make revisions to gain more accurate results.

    Skills you will learn:

    • Identify or come up with valid, testable questions from the provided data – Make and evaluate inquiries related to natural phenomena from a given set of data by experimentation, research, and discussion.
    • Identify null or alternative hypotheses and predict experimental results
    • Identify experimental procedures related to the question – Identify dependent and independent variables, controls, and justify the usage of these controls.
    • Gather data and state observations from results or laboratory setups – this is only assessed during your labs and you will not be tested on this in the actual AP Biology exam
    • Propose a new experiment – Evaluate the evidence and methods of a particular experiment and suggest a new experiment based on your questioning of natural phenomena and findings from the current experiment.
  4. Representing and Describing Data
    Communicating the data you have collected from an experiment is an important skill that any biologist must acquire. You will learn how to create graphs and understand which type of graph to use for any given data set.

    Skills you will learn:

    • Plot and construct a graph or chart – Learn how to construct line graphs, histograms, pie charts, box and whisker plots, dual y-axis graphs, and log Y graphs. You will be expected to know graph plotting techniques and design basics such as understanding how to label axes, orient variables on the graph, scale the graph, and even how to plot your units.
    • Describe data showcased in a graph or table – Identify data points from a table or chart, describe trends and patterns, and explain how variables are related in a graph or chart.
  5. Statistical Tests and Data Analysis
    You will learn to use mathematics to analyze data, solve problems, make predictions about natural phenomena, and showcase processes symbolically.

    Skills you will learn:

    • Use mathematical formulas to perform calculations – Calculations will include mean of a data set, rate calculations, rate of a reaction, ratios, and percentage of change, and equations in the AP Biology curriculum (these will be found in your formula sheet on exam day).
    • Confidence intervals and error bars – Learn to draw standard error bars and error bars for the 95% confidence interval to determine the difference between sample means, if any.
    • Chi-square hypothesis testing – Learn how to determine the chi-square value and the p-value of a data set and compare the two to draw conclusions about the given experiment.
    • Make predictions or evaluate hypotheses using data – This includes rejecting or not rejecting the null hypothesis and supporting or rejecting the alternative hypothesis.
  6. Argumentation

    Engaging in evidence-based scientific argumentation is of the most important skills any scientist could acquire. You will be expected to make sound arguments based on evidence from g biological processes and phenomena.

    Skills you will learn:

    • Making a claim – Learn how to describe data shown in a graph or table and draw conclusions from the experimental results.
    • Supporting claims using evidence – Use biological concepts, principles, data, and processes to justify a certain claim.
    • Reasoning – Understand how to use biological theories in justifying a claim by relating it to the evidence from an experiment.
    • Explaining relationships – Learn how to explain the relationship between results and broader biological theories, concepts, and processes.
    • Predict causes and effects – Describe the impact of disruption to biological components in a particular system using biological concepts, processes, visual representations, and data

This wraps up our sneak peek into the science practices taught in AP Biology. Now let’s break down the AP Biology topics starting with the 4 Big Ideas.

AP Biology’s 4 Big Ideas

The big ideas are nothing but the themes that will be explored through the AP Biology topics. They provide the foundation upon which the course is structured. These big ideas are interwoven into the multiple units of the course because they apply to various contexts. Let’s take a look at each of these big ideas.
  1. Evolution – The process that drives diversity and unity of life.

    Evolution is the change of gene frequencies in a population over time and leads to biodiversity within and among species. Charles Darwin’s theory explains how populations evolve through accumulating changes in their genes, won through the process of natural selection. Darwin observed that individuals with certain traits that benefit environmental conditions were able to survive and reproduce at higher rates, passing their genetic material on to future generations. With each new generation, the gene pool became more diverse.

    In addition to natural selection, gene pools can be altered by natural catastrophes and human-induced events. As the environment continues to change, organisms keep evolving with it, forming a vibrant and diverse ecosystem.

    The units you will study that further elaborate this Big Idea are: Cell Structure and Function, Heredity, Natural Selection, and Ecology.

  2. Energetics – Biological systems depend on energy and molecules to grow, reproduce, and maintain homeostasis.

    Living systems need energy and matter to facilitate growth, reproduction, and survival. They employ various methods to attain, use, and store this energy. Given that natural systems are interdependent and rely heavily on energy, any deficiencies in energy sources could have detrimental effects on populations and ecosystems.

    The units you will study that further elaborate this theme are: Chemistry of Life, Cell Structure and Function, Cellular Energetics, Cell Communication and Cell Cycle, and Ecology.

  3. Information Storage And Transmission – Living systems store, retrieve, transmit, and respond to information essential to various life processes.

    Genetic information is a repository of instructions necessary for the survival, growth, and reproduction of an organism. This information repository is stored in DNA, which is passed on from parent to offspring to promote the continuity of life. On the other hand, non-inheritable information influences behavior between cells, organisms, and populations. This reception of information is essential for evolution and natural selection.

    The units you will study that further elaborate this theme are: Chemistry of Life, Cell Communication and Cell Cycle, Heredity, Gene Expression and Regulation, and Ecology.

  4. Systems Interactions – Biological systems interact with each other exhibiting complex properties.

    All biological systems at the molecular and ecosystem levels interact with each other. With this comes enhanced diversity, which enables better resiliency and the ability to withstand environmental changes. The units you will study that further elaborate this theme are: Chemistry of Life, Cell Communication and Cell Cycle, Cellular Energies, Heredity, Natural Selection, and Ecology.

These 4 big ideas are interspersed throughout the AP Biology course and repeated in various units, as we’ve mentioned above. Now that we have our foundation, it’s time to delve into these units individually to understand the AP Biology topics you will learn.

The Eight Units of AP® Biology & Their Topics

The AP Biology course outline shows that the course is divided into eight units. Each unit will focus on one or more of the 4 big ideas. These units are further broken down into several topics that enable the learning of specific content and scientific practices. In this AP Biology course and exam description, we’ll look at each of these eight units, their weightage in the final AP Biology exam, and their related topics.

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While this is just an outline, we’ve also put together a detailed breakdown of this unit in our article AP Biology Unit 3 – Cellular Energetics.

AP Biology Labs: An Outline

The AP Biology labs were introduced in 1989 and have since been an excellent way for students to formulate scientific questions, perform experiments, and discuss various topics covered in the course. There are a total of 13 labs in the curriculum, and these may include experiments on artificial selection, diffusion and osmosis, cell division, photosynthesis, cellular respiration, and energy dynamics. Different AP Biology teachers may vary the experiments but the core concepts that will be taught are the same and will help improve your skills in scientific reasoning and analysis.

These labs aim to:

  1. Help you master the subject matter
  2. Develop the aptitude for scientific reasoning
  3. Understand the empirical work
  4. Help you develop practical skills
  5. Teach you the nature of science
  6. Drive your interest in scientific learning
  7. Develop your teamwork skills

As part of your labs, you will be required to pose questions, design experiments to test your hypotheses, conduct experiments, analyze the findings, and arrive at conclusive results. Read more about the 13 AP Biology Labs and pick up some quick tips to help you.

With this, we complete our introduction to the AP Biology course outline. Each of these AP Biology topics will help you develop an excellent foundation in biology that is well-rounded and robust. You can also get an idea of how you might be questioned on the units and topics we’ve discussed by trying out UWorld’s online AP Biology practice tests. You can personalize your test by choosing the units you want questions from and even the number of questions you want on your test! Our online tests offer detailed and illustrated answer explanations for each question and allow you to make flashcards with integrated spaced repetition technology.

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Frequently Asked Questions

A. The common themes of AP Biology are called the 4 Big Ideas. These are Evolution, Energetics, Information Storage and Transmission, and Systems Interactions.

A. Below is a list of the most important AP Biology topics based on their weighting on the exam:

  • (13–20%) Unit 7: Natural Selection
  • (12–16%) Unit 3: Cellular Energetics & Unit 6: Gene Expression and Regulation &
  • (10–15%) Unit 4: Cell Communication and Cell Cycle & Unit 8: Ecology
  • (10–13%) Unit 2: Cell Structure and Function
  • (8–11%) Unit 1: Chemistry of Life & Unit 5: Heredity

A. Taking high school biology is a prerequisite for taking AP Biology. So, you would need to study regular biology in order to take up AP Biology.

A. AP Biology is one of the easier AP Science courses. However, it also depends on your aptitude for studying biology, the amount of time you can dedicate to studying, etc.

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