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Environmental Science
Grade 11-12
AP Environmental Science Course Reference Cheat Sheet
A printable reference covering ecosystems, populations, biogeochemical cycles, energy flow, pollution, climate, and sustainability for grades 11-12.
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This AP Environmental Science course reference brings together the major ideas students need for APES review, classwork, and exam preparation. It connects living systems, Earth systems, human impacts, and sustainability in one clear study sheet. Students need this cheat sheet because APES questions often combine science concepts, data interpretation, and real-world environmental decisions.
Key Facts
- The rule of 10 states that about 10 percent of energy is transferred from one trophic level to the next, while most energy is lost as heat.
- Population growth can be modeled by r = (births + immigration) - (deaths + emigration), where r is the change in population size.
- The ecological footprint measures the amount of biologically productive land and water needed to support a person, population, or activity.
- Primary productivity measures the rate at which producers convert solar energy into chemical energy, with NPP = GPP - respiration.
- Half-life is the time required for half of a radioactive substance to decay, and remaining amount = original amount x (1/2)^number of half-lives.
- Percent change = ((new value - old value) / old value) x 100, and it is commonly used to compare environmental data over time.
- Carbon dioxide, methane, nitrous oxide, and water vapor are greenhouse gases that trap outgoing infrared radiation and warm Earth’s surface.
- Sustainability means using resources at a rate that meets current needs without reducing the ability of future generations to meet their needs.
Vocabulary
- Ecosystem
- An ecosystem is a community of living organisms interacting with each other and with the nonliving environment.
- Biodiversity
- Biodiversity is the variety of life in an area, including genetic, species, and ecosystem diversity.
- Carrying Capacity
- Carrying capacity is the maximum population size an environment can support over time with available resources.
- Watershed
- A watershed is an area of land where all water drains into the same river, lake, or other body of water.
- Eutrophication
- Eutrophication is the enrichment of water by nutrients that can cause algal blooms and low dissolved oxygen.
- Renewable Resource
- A renewable resource is a natural resource that can be replenished on a human time scale if managed sustainably.
Common Mistakes to Avoid
- Confusing energy flow with matter cycling is wrong because energy moves one way through ecosystems while matter is recycled through biogeochemical cycles.
- Using the 10 percent rule as an exact value is wrong because it is an average estimate and real energy transfer efficiency can vary by ecosystem.
- Forgetting units in APES calculations is wrong because environmental data often requires units such as ppm, kWh, hectares, metric tons, or percent.
- Assuming renewable always means pollution-free is wrong because renewable energy and resources can still have land use, habitat, mining, or waste impacts.
- Mixing up weather and climate is wrong because weather describes short-term atmospheric conditions while climate describes long-term patterns over decades.
Practice Questions
- 1 A forest has a gross primary productivity of 2400 kcal/m2/year and plant respiration of 900 kcal/m2/year. What is the net primary productivity?
- 2 A town used 80,000 kWh of electricity last year and 92,000 kWh this year. What is the percent increase in electricity use?
- 3 A radioactive isotope has an original mass of 64 grams and a half-life of 10 years. How much remains after 30 years?
- 4 Explain why protecting biodiversity can make ecosystems more stable and resilient after a disturbance.