AP Environmental Science has 80 MCQ and 3 FRQs. One FRQ always contains a mandatory math component — this is the most predictable part of the exam and one of the easiest places to gain points if you know the formulas.
Math FRQ: What You Must Know
The math FRQ tests dimensional analysis, energy calculations, and the Rule of 70. Dimensional analysis: write out every unit conversion step explicitly — you get partial credit for showing correct setup even if arithmetic is wrong. Energy unit conversions: know how to convert between joules, kilowatt-hours, and BTUs; read the provided data table carefully before calculating. Rule of 70: doubling time = 70 / growth rate (%). If a population grows at 2% annually, it doubles in 35 years. The exam often asks you to calculate and then interpret significance.
Solutions FRQ Strategy
For any question asking you to evaluate or propose a solution, always provide two things: (1) the mechanism — explain exactly how the solution works at a scientific or policy level, and (2) the tradeoff — name a specific cost, limitation, or unintended consequence. "Build more solar panels" earns no credit. "Installing utility-scale solar reduces fossil fuel combustion, cutting CO₂ emissions, but requires large land areas that can displace wildlife habitat or agricultural use" earns full credit.
Highest-Tested Units
- Unit 4 — Earth Systems and Resources: water cycle, rock cycle, soil formation, plate tectonics, and ocean circulation patterns. Know which processes are driven by solar energy vs. Earth's internal heat.
- Unit 6 — Energy Resources and Consumption: fossil fuels (extraction methods, environmental costs), nuclear fission, and renewable sources. Know EROI (energy return on investment) comparisons and the environmental impact of each source.
- Unit 7 — Atmospheric Pollution: primary vs. secondary pollutants, formation of tropospheric ozone (photochemical smog), acid deposition (NOₓ + SOₓ + H₂O reactions), and the Clean Air Act mechanisms.
APES Formulas to Memorize
- IPAT equation: I = P × A × T (Environmental Impact = Population × Affluence × Technology). Used to compare national environmental footprints.
- Per-capita consumption: total resource use ÷ population. A country can have low population but high per-capita impact.
- Energy unit conversions: 1 kWh = 3.6 × 10⁶ J. Provided conversion tables will give specific values — practice reading them quickly.
- Rule of 70: doubling time = 70 / r, where r is growth rate as a percentage.
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