AP Environmental Science
Topic breakdowns for all nine APES units, the case studies and laws you need to name, and the calculations that appear on every exam.
About the exam
Next exam13 May 2027
AP Environmental Science is equivalent to a one-semester introductory college course in environmental science. It combines biology, earth science, chemistry and geography to study how natural systems work, how people change them, and which solutions work.
About a quarter of the course is lab and field work. A score of 3 or higher can earn college credit or placement at many universities; check the policy of each university you apply to.
Exam format
Section I: Multiple choice60%
80 questions, single or in sets based on data, graphs, maps or text
Time: 90 min
Section II: Free response40%
3 questions: design an investigation; analyse an environmental problem and propose a solution; analyse a problem using calculations
Time: 70 min
| Section | Questions | Time | Share of score |
|---|---|---|---|
| Section I: Multiple choice | 80 questions, single or in sets based on data, graphs, maps or text | 90 min | 60% |
| Section II: Free response | 3 questions: design an investigation; analyse an environmental problem and propose a solution; analyse a problem using calculations | 70 min | 40% |
Fully digital exam in the Bluebook app. A calculator is allowed.
Units and exam weighting
Weighting is each unit's share of the multiple-choice section, as published by the exam board.
Unit 1: The Living World: Ecosystems
Ecosystems and biomes · Carbon, nitrogen, phosphorus and water cycles · Primary productivity · Trophic levels and the 10% rule · Food chains and food webs
6–8%Unit 2: The Living World: Biodiversity
Biodiversity · Ecosystem services · Island biogeography · Ecological tolerance · Natural disruptions · Adaptations · Ecological succession
6–8%Unit 3: Populations
Generalist and specialist species · K- and r-selected species · Survivorship curves · Carrying capacity · Age structure diagrams · Total fertility rate · Human population dynamics · Demographic transition
10–15%Unit 4: Earth Systems and Resources
Plate tectonics · Soil formation, composition and erosion · Earth's atmosphere · Global wind patterns · Watersheds · Solar radiation and seasons · Earth's geography and climate · El Niño and La Niña
10–15%Unit 5: Land and Water Use
Tragedy of the commons · Clearcutting · The Green Revolution · Agricultural practices and irrigation · Pest control · Meat production · Overfishing · Mining · Urbanization · Ecological footprints · Sustainability
10–15%Unit 6: Energy Resources and Consumption
Renewable and nonrenewable resources · Fossil fuels · Nuclear power · Energy from biomass · Solar, hydroelectric, geothermal and wind energy · Hydrogen fuel cells · Energy conservation
10–15%Unit 7: Atmospheric Pollution
Air pollutants · Photochemical smog · Thermal inversion · Indoor air pollutants · Reducing air pollutants · Acid rain · Noise pollution
7–10%Unit 8: Aquatic and Terrestrial Pollution
Sources of pollution · Endocrine disruptors · Wetlands and mangroves · Eutrophication · Thermal pollution · Persistent organic pollutants · Bioaccumulation and biomagnification · Solid waste · Sewage treatment · LD50 and dose-response · Pathogens and infectious diseases
7–10%Unit 9: Global Change
Stratospheric ozone depletion · The greenhouse effect · Increases in greenhouse gases · Global climate change · Ocean warming and acidification · Invasive species · Endangered species · Human impacts on biodiversity
15–20%
Question types and strategy
Multiple choice (80 questions)
Many questions ask you to read a graph, table, map or short text. Keep a steady pace: about one minute per question. There is no penalty for a wrong answer, so answer every question.
Design an investigation
State a testable hypothesis, identify the independent and dependent variables and a control, and describe what you would measure. See experimental design.
Environmental problem and solution
Name a specific cause and effect, then propose a realistic solution and one drawback of it. Use the case studies and laws you have learned: a named example earns more than a general statement.
Calculations
Expect unit conversions, percent change, energy and population calculations. Show every step, carry units through and round only at the end.
Topic breakdowns
Units 1–9, topic by topic.
Nothing here yet. New notes are added regularly.
Case studies & laws
Real-world examples and environmental legislation to quote in your answers.
Nothing here yet. New notes are added regularly.
Calculations & FRQ tips
Unit conversions, percent change, energy and population calculations without a calculator.
Nothing here yet. New notes are added regularly.