The exam at a glance
| Section | Weight | Timing | What you do |
|---|---|---|---|
| I · Multiple choice | 60% | 1 hr 30 min · 80 questions | Individual questions and sets built on tables, charts, graphs, models, maps and short texts. Explain concepts, analyze data and propose solutions. |
| II · Free response | 40% | 1 hr 10 min · 3 questions | Q1 Design an investigation. Q2 Analyze an environmental problem and propose a solution. Q3 Analyze a problem and propose a solution using calculations. |
Everything happens in Bluebook
You answer every question, including the written responses, in College Board's Bluebook testing app. Practice typing timed answers before May.
Calculator allowed, but show your math
A calculator is permitted on the whole exam. On calculation questions you must still show your setup and units to earn the points.
The multiple-choice section
80 questions in 90 minutes gives you about 1 minute 7 seconds per question, so speed matters more here than on most AP science exams. Wrong answers lose no points.
Strategies that work
- Keep moving. At about 1 minute per question, don't let one data set eat five minutes.
- Read the axes and units first on every graph or table.
- Know the classic examples: eutrophication, ozone depletion, acid rain, the tragedy of the commons.
- Choose the most specific answer that is directly supported by the data shown.
- Watch for "most likely" and "best": several choices may be true, but only one is best.
- Never leave a blank. Guess and flag, then return if time allows.
The 9 units, in plain English
The Living World: Ecosystems
How energy and matter move through nature.
Be ready to: Describe biomes; trace carbon, nitrogen, phosphorus and water cycles; calculate energy flow with the 10% rule.
The Living World: Biodiversity
Why variety matters.
Be ready to: Explain genetic, species and ecosystem diversity; ecosystem services; island biogeography; ecological succession.
Populations
How populations grow and change.
Be ready to: Compare r- and K-selected species; read survivorship curves and age-structure diagrams; calculate growth rate and doubling time; explain demographic transition.
Earth Systems & Resources
The physical planet.
Be ready to: Explain plate tectonics, soil formation, atmosphere layers, global wind patterns, watersheds and El Niño.
Land & Water Use
Farming, forestry, mining and cities.
Be ready to: Compare agricultural practices, irrigation, pest control, forestry, mining and urbanization; explain the tragedy of the commons and sustainable methods.
Energy Resources & Consumption
Where our energy comes from.
Be ready to: Compare fossil fuels, nuclear and renewables; explain how electricity is generated; calculate energy use and cost; describe efficiency and conservation.
Atmospheric Pollution
Air quality.
Be ready to: Identify primary and secondary pollutants; explain photochemical smog, thermal inversions, acid deposition and indoor pollution; describe Clean Air Act controls.
Aquatic & Terrestrial Pollution
Water, soil and waste.
Be ready to: Explain eutrophication, dissolved oxygen, sewage treatment, bioaccumulation and biomagnification, LD50 and solid waste.
Global Change
Climate, ozone and biodiversity loss.
Be ready to: Explain stratospheric ozone depletion, the greenhouse effect and climate change impacts, ocean acidification, invasive species and endangered species.
Global change is the single biggest unit, and Units 3–6 together are about half of the multiple-choice section. Laws and treaties appear often: know the purpose of the Montreal Protocol, Clean Air Act, Clean Water Act, Endangered Species Act and CITES.
The 3 free-response questions
70 minutes for 3 questions, each worth 10 points (30 raw points, 40% of your score). The three question types are the same every year.
Design an investigation
Identify a research question, hypothesis, variables and controls, then describe data collection and explain results for an environmental scenario.
Name the independent variable, dependent variable and one specific control.
Analyze a problem and propose a solution
Describe environmental concepts shown in a diagram or data, explain effects, and propose and justify a solution.
A solution needs an action and how it reduces the problem.
Analyze a problem with calculations
Use calculations (percent change, unit conversion, energy, population growth) to analyze a scenario, then propose and justify a solution.
Show setup and units at every step; the answer alone may earn nothing.
Time plan: Skim for 3 minutes, then about 22 minutes per question. When a question asks you to "identify", one word can do it; "explain" needs a full cause-and-effect sentence.
Habits that earn points
- Match the task verb: identify, describe, explain, justify.
- Show setup and units for every calculation.
- Give one specific example per point; extras aren't scored.
- Propose solutions with an action and a reason.
- Stuck? Answer the other lettered parts; each scores separately.
10 traps that cost points
Ozone vs climate change
Stratospheric ozone depletion increases UV-B reaching Earth. It is not the main cause of global warming.
Good vs bad ozone
Stratospheric ozone protects us; ground-level ozone is a secondary pollutant in photochemical smog.
Eutrophication sequence
Nutrients → algal bloom → algae die → decomposers use O₂ → hypoxia → fish die-off. Don't skip the decomposers.
Bioaccumulation vs biomagnification
Bioaccumulation builds up in one organism over time; biomagnification increases up a food chain.
Vague solutions
"Reduce pollution" earns nothing. Name a specific action and explain how it works.
Doubling time
Rule of 70: doubling time ≈ 70 ÷ growth rate in percent. Use 2, not 0.02.
Renewable vs clean
Biomass and hydroelectric are renewable but still have environmental impacts. Nuclear is low-carbon but not renewable.
Correlation as cause
Data showing two trends together doesn't prove one causes the other. Say "is associated with".
Missing units
A calculation answer without units or a setup may score zero on Q3.
Too many examples
If asked for one example, only the first one is scored. Make it your best.
A study roadmap to May
A steady plan beats a last-minute rush. Shift the months to match your teacher's pacing.
- Sep – Oct
Units 1–3: the living world
Ecosystems, cycles, biodiversity and population dynamics. Learn the rule of 70 and percent change early.
- Nov – Dec
Units 4–5: Earth and land
Earth systems, soil, agriculture, water use and urbanization. Start one free-response question per week.
- Jan – Feb
Unit 6: energy
Fossil fuels, nuclear and renewables. Practice energy and cost calculations (Q3 style).
- Mar – Apr
Units 7–9: pollution and global change
Air, water and land pollution, then climate change and biodiversity loss. Begin timed 80-question sets.
- Early May
Free-response drills
All three question types under timing. Review laws, treaties and the traps list.
- May 2027
Exam day
Thursday, May 13, 2027 (afternoon session). Sleep well and confirm your start time with your AP coordinator.
3 practice questions
Original questions written by ACT SAT GO in the style of the exam. The free PDF has 10, with full explanations.
- Unit 3 · Population growth
A country has a crude birth rate of 30 per 1,000 and a crude death rate of 10 per 1,000, with no migration. What is its approximate doubling time?
- A 20 years
- B 35 years
- C 50 years
- D 70 years
Show answer
Answer: B · 35 years. Growth rate = (30 − 10)/1,000 = 2% per year. Rule of 70: 70 ÷ 2 = 35 years.
- Unit 7 · Smog
Photochemical smog in a city usually peaks in the early afternoon. What best explains this timing?
- A Nighttime cooling traps pollutants
- B Rain washes pollutants out in the morning
- C Morning traffic releases NOx and VOCs, and sunlight drives reactions that form ozone
- D Power plants only operate in the afternoon
Show answer
Answer: C. Morning commute emissions of NOx and VOCs react in sunlight, forming ground-level ozone, which peaks after midday.
- Unit 2 · Island biogeography
According to island biogeography theory, which island would be expected to have the highest species richness?
- A Large island close to the mainland
- B Small island far from the mainland
- C Small island close to the mainland
- D Large island far from the mainland
Show answer
Answer: A. Large islands have more habitats and lower extinction rates; nearby islands receive more immigrants. Both increase species richness.
How students score
Ranges reflect recent College Board score distributions and shift a little each year. Credit and placement policies vary by college.
Aiming for a 5 in AP Environmental Science?
Book a free diagnostic session. We'll find your weakest units, review your practice responses and give you a week-by-week plan to exam day.