AP® Environmental Science Course And Exam Description
In AP® Environmental Science, you’ll dive deep into environmental concepts to understand the environment, tackle issues and challenges associated with it, and come up with smart solutions to address those problems. These solutions will include scientific methods that affect our environment and society.
The AP Environmental Science course is equivalent to a one-semester, introductory college course1 on the subject. If you’re planning to take the APES course and exam, it is important to familiarize yourself with its course content.
In this easy-to-understand course and exam description guide, we'll break down the APES course outline, talk about the units and topics tested, and explore the key concepts you'll be mastering. This will help you prepare a thorough study plan and make your exam prep hassle-free.
AP Environmental Science Units, Topics and Key Concepts
The APES course is made up of two components:
- Course Content, and
- Its associated Science Practices
The course content is divided into 8 widely taught units. These units are connected to each other with overlapping themes, called big ideas. There are four big ideas in the course, which we will explore soon. In addition, the course covers 7 types of science practices, which you’ll acquire as you journey through these units. Let’s start with the big ideas first, and then we’ll move on to the course units and skills.
AP Environmental Science’s Four Big Ideas
The big ideas are the basis of the course and help students make connections between course units and concepts. Students can get a deeper understanding of the big ideas by applying them in different ways as they go through each unit. Listed below are the big ideas2 for the APES course, with a short description of each:
BIG IDEA 1: ENERGY TRANSFER (ENG)
Energy transformations drive all ecological processes. Energy cannot be created; it can only change forms from one type to another (eg.: from potential to kinetic energy). As energy passes through systems, a greater proportion of it is wasted at each step.BIG IDEA 2: INTERACTIONS BETWEEN EARTH SYSTEMS (ERT)
The Earth is made up of interconnected biochemical systems that work together to create the stable ecosphere we call “earth”. These individual systems change over time and space, and each system has a different threshold for recovering from damage or disturbances.BIG IDEA 3: INTERACTIONS BETWEEN DIFFERENT SPECIES AND THE ENVIRONMENT (EIN)
For millions of years, humans have altered Earth’s natural systems, which have had an enormous impact on the environment. The nature and pace of this impact have grown exponentially with the development of technology and population growth.BIG IDEA 4: SUSTAINABILITY (STB)
To survive and thrive, we need sustainable systems. That means finding the perfect balance between conserving and developing resources. Managing our resources wisely is super important. As we work towards developing solutions, we need to understand that cultural, social, and economic factors play a big role in finding solutions.
AP Environmental Science’s 9 Units and Their Topics
As you may already know, the big ideas we discussed above spiral through the 9 course units of APES3. As you go through the course, you’ll realize that one or more of these big ideas reappear in each unit. Although there are 9 units in the course, some units have more weight than others, especially in the multiple-choice section. This means that you’ll get more questions from these units compared to others. The table below lists the units and their respective weights in Section I of the exam:
| Units | Weighting |
|---|---|
| Unit 1: The Living World: Ecosystems | 6–8% |
| Unit 2: The Living World: Biodiversity | 6–8% |
| Unit 3: Populations | 10–15% |
| Unit 4: Earth Systems and Resources | 10–15% |
| Unit 5: Land and Water Use | 10–15% |
| Unit 6: Energy Resources and Consumption | 10–15% |
| Unit 7: Atmospheric Pollution | 7–10% |
| Unit 8: Aquatic and Terrestrial Pollution | 7–10% |
| Unit 9: Global Change | 15–20% |
If you want to learn more about any of the AP Environmental Science units, you can click on the unit widgets below:
The first unit establishes the course’s basis by exploring the Earth as a system with interrelated components, processes, and relationships. This unit identifies how resources are spread out in ecosystems and how this affects the way species interact with each other. In this unit, students will study biomes and how environmental circumstances affect organismal relationships. They will learn to quantify energy loss in ecosystems and explain the transfer of energy.
You will learn about the following topics:
- Introduction to Ecosystems
- Terrestrial Biomes
- Aquatic Biomes
- The Carbon Cycle
- The Nitrogen Cycle
- The Phosphorus Cycle
- The Hydrologic (water) Cycle
- Primary Productivity
- Trophic Levels
- Energy Flows and the 10% Rule
- Food Chains and Food Webs
Biodiversity refers to the variety of genes, species, and habitats. Biodiversity is an important part of ecosystems because it helps keep life going. In this unit, students will be able to explain and describe the ideas and processes of biodiversity that have to do with the environment. It’s important that students know the differences between similar concepts and ideas, and can explain those differences both in writing and in person.
You will learn about the following topics:
- Introduction to Biodiversity
- Ecosystem Services
- Island Biogeography
- Ecological Tolerance
- Natural Disruptions to Ecosystems
- Adaptations
- Ecological Succession
Populations within ecosystems evolve over time as a result of numerous variables. This unit explores the connections between the type of species and changes in an ecosystem. Students may find it helpful to have multiple chances to practice mathematical calculations like figuring out the growth of a population and how to use the rule of 70 in this course. Students can also work on choosing the right calculation that is needed to analyze a set of data.
You will learn about the following topics:
- Generalist and Specialist Species
- K-selected r-selected Species
- Survivorship Curves
- Carrying Capacity
- Population Growth and Resource Availability
- Age Structure Diagram
- Total Fertility Rate
- Human Population Dynamics
- Demographic Transition
This unit examines earth systems and life-sustaining resources. Changes to Earth’s systems at convergent and divergent boundaries can cause mountains, island arcs, earthquakes, volcanoes, and seafloor spreading. In this unit, students can practice analyzing and understanding qualitative models and representations of environmental issues. Students should be able to identify and describe environmental processes that are visibly displayed.
You will learn about the following topics:
- Plate Tectonics
- Soil Formation and Erosion
- Soil Composition and Properties
- Earth’s Atmosphere
- Global Wind Patterns
- Watersheds
- Solar Radiation and Earth’s Seasons
- Earth’s Geography and Climate
- El Nino and La Nina
This unit explores human activities that disrupt ecosystems in both beneficial and negative ways, as well as the measures used to mitigate their effects. It looks at how people use natural resources, like mining and clear-cutting, and how that affects the environment. In this unit, students can practice naming environmental problems like pollution, the depletion of the ozone layer, and global climate change.
You will learn about the following topics:
- The Tragedy of the Commons
- Clearcutting
- The Green Revolution
- Impacts of Agricultural Practices
- Irrigation Methods
- Pest Control Methods
- Meat Production Methods
- Impacts of Overfishing
- Impacts of Mining
- Impacts of Urbanization
- Ecological Footprints
This unit will analyze the effects that human consumption of renewable and nonrenewable sources of energy has had on the surrounding ecosystem. Energy consumption varies around the world, and the availability of energy resources is determined by the geologic history of the region. In this unit, students will learn how to find sources of natural energy resources like coal, crude oil, and ore on the world map.
You will learn about the following topics:
- Renewable and Non-renewable Resources
- Global Energy Consumption
- Fuel Types and Uses
- Distribution of Natural Energy Resources
- Fossil Fuels
- Nuclear Power
- Energy from Biomass
- Solar Energy
- Hydroelectric Power
- Geothermal Energy
- Hydrogen Fuel Cell
- Wind Energy
- Energy Conservation
Air is a natural resource that covers the whole planet and flows through many different systems. Both inside and outside, the air quality is affected by what people do. In this unit, students can practice comparing and predicting patterns and/or trends in a graph or table to explain how the data or representation shows environmental concepts. Students can also practice coming up with ways to fix the health problems caused by air pollution.
You will learn about the following topics:
- Introduction to Air Pollution
- Photochemical Smog
- Thermal Inversion
- Atmospheric CO2 and Particulates
- Indoor Air Pollutants
- Reduction of Air Pollutants
- Acid Rain
- Noise Pollution
Human actions that cause pollution have a direct effect on ecosystems in the air, on land, and in water. Sometimes it’s easy to figure out where pollution comes from, but other times it’s hard to tell. There are numerous problems affecting human health that have been connected to pollution. Students should be able to look at an environmental problem with a critical eye and evaluate a given solution, pointing out its pros and cons.
You will learn about the following topics:
- Sources of Pollution
- Human Impacts on Ecosystems
- Endocrine Disruptors
- Human Impacts on Wetlands and Mangroves
- Eutrophication
- Thermal Pollution
- Persistent Organic Pollutants (POPs)
- Bioaccumulation and Biomagnification
- Solid Waste Disposal
- Waste Reduction Methods
- Sewage Treatment
A big part of environmental science is trying to figure out how local and regional human actions affect the world as a whole. People can lessen their effects by using resources in a sustainable way. Human actions can deplete the amount of ozone in the stratosphere and make the amount of greenhouse gases in the air rise. When greenhouse gases increase, it can hurt people’s health and the environment.
The purpose of this final unit is for students to describe and explain global environmental changes, their causes, and their implications. As they learn about problems caused by global changes in the environment, students can use the skills they learned in previous units, where they described and rated solutions, to come up with their own solutions.
You will learn about the following topics:
- Stratospheric Ozone Depletion
- Reducing Ozone Depletion
- The Greenhouse Effect
- Increase in Greenhouse Gases
- Global Climate Change
- Ocean Warming
- Ocean Acidification
- Invasive Species
- Endangered Species
- Human Impacts on Biodiversity
What Are the Science Practices for the AP Environmental Science Course
The AP ES science practices explain the skills a student should acquire during the course and be able to execute in the exam. Listed below are the 7 skill categories that you should master by the end of your APES course. Note that questions on the exam will ask you to solve problems by using one or more of these science practices4.
Science Practice 1: Concept Explanation
You’ll learn to explore environmental concepts, processes, and models in written form.
You will learn how to:
- Describe and explain environmental concepts and processes in applied contexts.
Science Practice 2: Visual Representations
You’ll learn to explore visual representations of environmental concepts and processes.
You will learn how to:
- Describe and explain how the visual representation of an environmental concept, process, or model relates to broader environmental challenges.
Science Practice 3: Text Analysis
This science practice will help you analyze sources of information about environmental issues.
You will learn how to:
- Define the author's point of view.
- Describe the author's viewpoint, assumptions, and reasoning.
- Analyze the reliability of a source and assess the soundness of a study's findings.
Science Practice 4: Scientific Experiments
The fourth science practice will teach you how to analyze research studies that focus on environmental principles.
You will learn how to:
- Find a hypothesis or scientific question prior to conducting an investigation.
- Specify the methodology, design, and/or measurement employed.
- Describe an aspect of the employed study method, design, or measure.
- Observe laboratory settings or collect data from them.
- Describe alterations to a procedure that will affect the results.
Science Practice 5: Data Analysis
You’ll learn to analyze and interpret quantitative data presented in tables, charts, and graphs.
You will learn how to:
- Describe data-based patterns.
- Describe connections between variables represented in data.
- Explain data trends and patterns to draw a conclusion.
- Analyze experimental data and outcomes in light of the specified hypothesis.
- Explain what the evidence suggests or indicates regarding environmental concerns.
Science Practice 6: Mathematical Routines
The sixth science practice will teach you how to use quantitative methods to talk about ideas about the environment.
You will learn how to:
- Identify a strategy or method that corresponds to the problem to be tackled.
- Utilize relevant mathematical relationships, such as dimension analysis, to solve an issue.
- Calculate a precise numerical answer using the correct units.
Science Practice 7: Environmental Solutions
You’ll learn how to identify solutions to environmental problems.
You will learn how to:
- Describe and explain environmental problems.
- Describe potential solutions or methods for environmental issues.
- Describe downsides, advantages, or unforeseen consequences for suggested solutions.
- Use info and evidence supporting a prospective solution.
- In an applied context, make a claim that provides a remedy to an environmental issue.
- Clarify a suggested solution by describing its potential benefits.
Frequently Asked Questions
How many topics are there in AP Environmental Science?
What are the most important units in AP Environmental Science?
The top 5 units carrying the most number of questions on the APES MCQ section can be considered more important than other units. These units are listed below:
- Unit 9: Global Change (15–20%)
- Unit 3: Populations (10–15%)
- Unit 4: Earth Systems and Resources (10–15%)
- Unit 5: Land and Water Use (10–15%)
- Unit 6: Energy Resources and Consumption (10–15%)
References
1(2024). College Course Equivalent. Equivalency and Prerequisites. AP Environmental Science. College Board. Retrieved on March 11, 2024 from
https://apstudents.collegeboard.org/courses/ap-environmental-science
2(2019). Big Ideas. Course Content. AP® Environmental Science COURSE AND EXAM DESCRIPTION. Retrieved on March 11, 2024 from
https://apstudents.collegeboard.org/sites/default/files/2019-05/ap-environmental-science-course-and-exam-description.pdf
3(2024). Course Content. AP Environmental Science. Retrieved on March 11, 2024 from
https://apstudents.collegeboard.org/courses/ap-environmental-science
4(2019). Science Practices. AP Environmental Science. Retrieved on March 11, 2024 from
https://apstudents.collegeboard.org/sites/default/files/2019-05/ap-environmental-science-course-and-exam-description.pdf