AP Environmental Science 7-Day Cram Plan

With one week left, you can touch every major unit, lock in patterns, and run a full mock exam. This plan assumes 3-4 hours per day; adjust depth based on your confidence.

Daily Schedule

Monday: Unit 1 — Ecosystems & Energy Flow (3 hrs)

Topics to lock down (60 min)

• 10% rule: only ~10% of energy transfers from one trophic level to the next.
• Biogeochemical cycles: carbon, nitrogen, phosphorus, water. Know human disruptions.
• Food chains vs. webs; bioaccumulation in organisms, biomagnification up the food chain.
• Net primary productivity (NPP) varies by biome.

Practice (2 hrs)

• 15 multiple-choice on energy flow, cycles, biomes.
• Scenario: "A lake receives agricultural runoff high in nitrogen. Predict the food web changes."

💡 Cycle focus: Draw each cycle on paper. Label atmosphere, soil, water, organisms, and human inputs (fertilizers, fossil fuels, deforestation).

Tuesday: Unit 2 — Biodiversity & Ecosystem Services (3 hrs)

Topics to lock down (60 min)

• Primary vs. secondary succession; pioneer species; climax communities.
• Island biogeography: species richness depends on island size and distance from mainland.
• Carrying capacity ($K$) and niche differentiation.
• Ecosystem services: carbon sequestration, pollination, nutrient cycling, water purification.
• Tolerance and range of tolerance (habitat range).

Practice (2 hrs)

• 15 multiple-choice on succession, biogeography, ecosystem services.
• Diagram a 5-step primary succession sequence (bare rock → pioneer → intermediate → climax).

Wednesday: Unit 3 — Populations & Unit 4 — Earth Systems (3.5 hrs)

Topics to lock down (90 min)

Unit 3 — Populations

• Exponential growth: $N_t = N_0 e^{rt}$. Doubling time: $t = \frac{\ln(2)}{r}$.
• Logistic growth: $\frac{dN}{dt} = rN(1 - \frac{N}{K})$. Inflection point at $N = K/2$.
• $r$-selected species (rabbits, insects): many offspring, fast development, high mortality.
• $K$-selected species (elephants, whales): few offspring, long development, parental care.
• Demographic transition: Stage 1–5. Stage 2 (high birth, low death) = population explosion. Stage 4 (low birth/death) = stable or shrinking.

Unit 4 — Earth Systems

• Soil: O-horizon (organic), A-horizon (topsoil), B-horizon (subsoil), C-horizon (parent rock). Erosion and salinization threats.
• Plate tectonics: seafloor spreading, subduction, mineral extraction, earthquake risk.
• Atmosphere: composition, greenhouse effect (longwave radiation trapped), enhanced greenhouse effect (excess CO₂).
• Watersheds and groundwater: infiltration, aquifer depletion, runoff.

Practice (2.5 hrs)

• 20 mixed MCQs.
• Scenario: "A population has $r = 0.05$ and $N_0 = 1000$. Calculate population after 10 years (exponential model). Then discuss what carries capacity might be in the habitat."

Thursday: Unit 5 — Land & Water Use & Unit 6 — Energy Resources (3.5 hrs)

Topics to lock down (90 min)

Unit 5 — Land & Water Use

• Agriculture: monoculture, soil depletion, irrigation (aquifer depletion, salinization), pesticides (bioaccumulation), GMOs.
• Fishing: overfishing, bycatch, ecosystem disruption.
• Mining: habitat destruction, acid mine drainage, mercury/heavy metal release.
• Urbanization: habitat loss, heat islands, stormwater runoff.
• Deforestation: carbon release, biodiversity loss, soil erosion.

Unit 6 — Energy Resources

• Fossil fuels: coal (highest carbon intensity, SOₓ emissions), oil (spills, extraction), natural gas (methane leaks, flare stacks).
• Renewables: solar (15-20% efficiency, land use ~5 acres/MW), wind (capacity factor 25-40%, avian deaths), hydro (reservoir methane, ecosystem disruption), geothermal (limited areas).
• Nuclear: no CO₂ at generation, but waste disposal, decommissioning, security costs.
• Energy efficiency: insulation R-value, SEER (cooling), LED vs. incandescent (85% savings), appliance efficiency.

Practice (2.5 hrs)

• 20 mixed MCQs.
• Proposal: "Design a 50% renewable-energy transition for a city. Include feasibility, land-use impacts, cost trade-offs."

Friday: Units 7 & 8 — Atmospheric, Aquatic & Solid Waste Pollution (3.5 hrs)

Topics to lock down (90 min)

Unit 7 — Atmospheric Pollution

• Criteria pollutants: CO (incomplete combustion; affects hemoglobin), NO₂ (acid rain, respiratory), SO₂ (acid rain, coal), O₃ (photochemical smog), PM2.5 (lung lodging), Pb (removed from US gas but old paint, old pipes).
• Photochemical smog: NOₓ + VOCs + sunlight → ground-level O₃ (LA, Houston).
• Classical smog (sulfurous): SO₂ + particulates + fog (London, Beijing).
• Acid rain: SO₂ → H₂SO₄, NO₂ → HNO₃. pH < 5.6. Effects on aquatic life, forests, limestone structures.
• Indoor air pollution: radon, CO, mold, formaldehyde.
• Noise pollution: dB scale (decibel), transport/industrial sources.

Unit 8 — Aquatic & Terrestrial Pollution

• Point source (factory outfall) vs. nonpoint (agricultural runoff, atmospheric deposition).
• Eutrophication: N/P excess → algal bloom → decomposition → hypoxia ("dead zone", Mississippi River).
• Thermal pollution: power plant cooling water, affects organism metabolism and oxygen solubility.
• Bioaccumulation: organism accumulates contaminant over time.
• Biomagnification: concentration increases up the food chain (mercury, PCBs, DDT).
• Solid waste: landfill leachate (contaminates groundwater), incineration (ash toxins, energy recovery).
• Hazardous waste: characterization (TCLP), disposal (deep injection, secure landfill).

Practice (2.5 hrs)

• 20 mixed MCQs.
• Scenario: "A lake shows high mercury levels in fish but low in water. Explain biomagnification. Propose monitoring and remediation."

Saturday: Unit 9 — Global Change (3 hrs)

Topics to lock down (75 min)

• Ozone depletion: CFCs (Freon) release Cl atoms → catalyze O₃ breakdown. Montreal Protocol phased out CFCs; recovery ongoing.
• Climate change drivers: CO₂ (fossil fuels, deforestation, cement), CH₄ (livestock, rice, wetlands, landfills), N₂O (agriculture), radiative forcing (W/m²).
• Climate effects: temperature rise, sea-level rise (thermal expansion + ice sheet melt), ocean acidification ($\text{CO}_2 + \text{H}_2\text{O} \rightarrow \text{H}^+ + \text{HCO}_3^-$, lowers pH, threatens shell-forming organisms), species range shifts, drought/flooding, coral bleaching.
• Carbon cycle perturbation: deforestation reduces carbon sink; fossil fuel combustion increases source.
• Invasive species: biogeographic barriers removed; no natural predators → outcompete natives.
• Conservation: protected areas, genetic diversity, captive breeding, habitat corridors.
• Mitigation vs. adaptation: carbon sequestration, renewable transition (mitigation) vs. drought-resistant crops, coastal barriers (adaptation).

Practice (2.25 hrs)

• 20 mixed MCQs.
• Comparison: "Distinguish three climate change drivers from three climate effects. For each driver, propose one mitigation strategy."

🎯 Critical distinction: Drivers are causes (CO₂, CH₄). Effects are results (warming, sea-level rise, acidification, extinction risk).

Sunday: Full Mock Exam + Review (3 hrs)

Timed Mock Exam (2 hrs exactly)

• Section I: 50 multiple-choice, 1 hour (no calculator for portion, then calculator for remainder — simulate your exam's structure).
• Section II: 3 FRQs, 1 hour. Types: Design Investigation, Problem-Solve with trade-offs, Quantitative Analysis.

Review (1 hr)

• Score using the FRQ practice guide →.
• Identify weak topics; re-read that unit's Day recap.
• If scoring <65%, focus Monday-Wednesday before exam on that unit.

Each day: practice math cold

Carry these formulas with you:

• Exponential: $N_t = N_0 e^{rt}$ or $N_t = N_0(1+r)^t$
• Doubling time: $t = \frac{\ln(2)}{r}$
• Percent change: $\frac{\text{new} - \text{old}}{\text{old}} \times 100$
• Energy conversion: 1 kWh = 3.6 MJ; 1 BTU ≈ 1055 J

What makes Day 7 crucial

The mock exam reveals gaps. If you scored 65+, you're on track for a 3-4 and likely a 5 with steady review. Below 65? Focus your final days on the unit(s) where you missed the most.

Ready to dive in? Start with Monday's ecosystems topic → or jump to FRQ practice →.