AP sciences and calculus · 35 cards · sources listed below

AP Environmental Science flashcards by unit

This starter set covers ideas that recur across the nine APES units: energy flow, nutrient cycles, population dynamics, resources, pollution and climate. It is an independent study aid, not affiliated with the College Board. It is a starter set of core terms and relationships, not a full APES review.

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Free AP Environmental Science flashcards: 35-card starter set

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Units 1-3: Ecosystems, Biodiversity and Populations (13)

How much energy typically transfers between trophic levels?

About 10 percent. The rest is lost as heat in metabolism or remains unconsumed, which limits the length of food chains.

GPP vs NPP

Gross primary productivity is total energy captured by producers. Net primary productivity = GPP - energy used in respiration, the energy available to consumers.

Detritivore vs decomposer

Detritivores (earthworms, millipedes) eat dead material. Decomposers (fungi, bacteria) break it down chemically, returning nutrients to the soil.

Name the steps of the nitrogen cycle.

Nitrogen fixation (N2 to ammonia/ammonium), nitrification (to nitrite then nitrate), assimilation by plants, ammonification of waste and dead matter, and denitrification (nitrate back to N2 gas).

What makes the phosphorus cycle different from the carbon and nitrogen cycles?

It has no significant atmospheric phase. Phosphorus moves through rocks, soil and water, and it is often the limiting nutrient in freshwater.

What is a keystone species?

A species with an effect on its ecosystem much larger than its abundance suggests, e.g. sea otters controlling urchins that graze kelp.

Name the three levels of biodiversity.

Genetic diversity, species diversity and ecosystem diversity.

What does island biogeography predict?

Larger islands and islands closer to the mainland hold more species, because extinction rates are lower and immigration rates higher.

Primary vs secondary succession

Primary starts with no soil (bare rock, new lava). Secondary follows a disturbance that leaves soil in place, so it is faster.

r-selected vs K-selected species

r-selected: many small, fast-maturing offspring with little care (e.g. insects). K-selected: few offspring, slow growth and heavy parental care (e.g. elephants), near carrying capacity.

What is the rule of 70?

Doubling time in years = 70 / percent annual growth rate.

What fertility rate is usually called replacement-level in developed countries?

A total fertility rate of about 2.1 children per woman.

Read an age-structure diagram.

A wide base (many young people) means rapid growth; a roughly rectangular shape means stable; a narrow base means decline.

Units 4-6: Earth Systems, Land and Water Use, Energy (10)

Soil horizons from the surface down

O (organic), A (topsoil), E (leached zone), B (subsoil), C (weathered parent material), then bedrock.

Describe the main types of plate boundaries.

Divergent: plates move apart (new crust). Convergent: plates collide (subduction, mountains, volcanoes). Transform: plates slide past each other (earthquakes).

What is the tragedy of the commons?

Individuals acting in their own interest overuse a shared resource (fisheries, grazing land), leading to its depletion.

Clear-cutting vs selective cutting

Clear-cutting removes all trees, increasing erosion and runoff but costing less. Selective cutting removes some trees and is less disruptive.

What defines integrated pest management (IPM)?

Combining biological control, cultural practices, monitoring thresholds and limited targeted pesticide use to reduce pests with less environmental harm.

What were the main components of the Green Revolution?

High-yield crop varieties, synthetic fertilizers, irrigation and pesticides, which raised yields but added environmental costs.

Consequences of aquifer overdraft

Falling water tables, land subsidence, saltwater intrusion near coasts and dry wells.

Which fossil fuel releases the most CO2 per unit of energy?

Coal, followed by oil, with natural gas the lowest of the three.

Nuclear power: advantages and drawbacks

Low operating greenhouse gas emissions and high power output, but radioactive waste that stays hazardous for long periods, plus accident and cost concerns.

Solar photovoltaic vs solar thermal

Photovoltaic cells convert light directly to electricity. Solar thermal concentrates or collects heat to warm water or make steam.

Units 7-9: Pollution and Global Change (12)

Primary vs secondary pollutants

Primary pollutants are emitted directly (CO, SO2, NOx). Secondary pollutants form from reactions in the air (ground-level ozone, PAN).

How does photochemical smog form?

NOx and volatile organic compounds react in sunlight to produce ground-level ozone and other oxidants.

What depleted the stratospheric ozone layer, and what addressed it?

Chlorine from CFCs. The 1987 Montreal Protocol phased them out.

Match each US law with its focus: NEPA, ESA, Clean Water Act, CERCLA.

NEPA (1969): environmental impact statements. ESA (1973): endangered species protection. Clean Water Act (1972): surface water pollution. CERCLA (1980, Superfund): cleanup of hazardous waste sites.

What causes acid deposition?

SO2 and NOx from burning fossil fuels form sulfuric and nitric acids in the atmosphere, falling as acid rain or dry deposition. Normal rain is slightly acidic, about pH 5.6.

Sequence of eutrophication

Excess nitrogen and phosphorus cause algal blooms; algae die and decomposers use up oxygen (high BOD); dissolved oxygen drops and fish die.

Bioaccumulation vs biomagnification

Bioaccumulation: a toxin builds up in one organism over time. Biomagnification: its concentration increases at each higher trophic level (e.g. DDT, mercury).

How does the greenhouse effect warm the planet?

Gases such as CO2, CH4, N2O and water vapor absorb outgoing infrared radiation and re-emit it, warming the lower atmosphere.

What are global warming potentials of methane and nitrous oxide compared with CO2 (100-year)?

Using IPCC AR6 values reported by the EPA: CH4 about 27-30 times CO2, N2O about 273 times, with CO2 as the baseline of 1.

Why does ocean acidification harm shellfish and corals?

Dissolved CO2 forms carbonic acid, lowering pH and reducing carbonate ions that organisms use to build shells and skeletons.

Give an example of a positive climate feedback.

Ice-albedo feedback: melting ice exposes darker surfaces that absorb more sunlight, causing more warming and more melting.

Two causes of sea level rise from warming

Thermal expansion of seawater and added water from melting land ice such as glaciers and ice sheets.

What this set covers

Course units covered

All 9: Living World Ecosystems; Living World Biodiversity; Populations; Earth Systems and Resources; Land and Water Use; Energy Resources and Consumption; Atmospheric Pollution; Aquatic and Terrestrial Pollution; Global Change.

Best used for

Learning vocabulary, cycles and the major laws, and quick review of calculations like the rule of 70.

Not covered

Case studies, data interpretation and free-response practice. Use your textbook and past questions for those.

How to study this set

APES questions often ask you to connect a human action to an environmental effect. Cards should capture those chains.

1
Day 1
Study one unit group. For each cycle or process, draw it from memory and name inputs, outputs and human impacts.
2
Days 2-7
Review missed cards and practise a few rule-of-70 and percent-change calculations with units.
3
Week 2
Mix units and for each pollutant say source, effect and one solution, since free-response questions use that pattern.
4
Final week
Review laws and their purposes, then practise explaining trade-offs for energy and land-use options.

Spaced repetition schedules each card to come back just before you would forget it, so reviews get shorter as your recall gets stronger. Cards you miss come back sooner.

Common mistakes to avoid

Confusing similar terms

Bioaccumulation vs biomagnification, primary vs secondary pollutant and GPP vs NPP are classic swaps. Write the distinction on the card.

Listing effects without a chain

Explain each step (fertilizer runoff, algae growth, oxygen drop, fish kill) instead of naming only the first and last.

Treating renewables as having no impact

Strong answers describe real trade-offs, such as habitat disruption from dams or mining for solar materials.

Skipping units in calculations

Show setup and units, and check whether a rate is a percent or a decimal before applying the rule of 70.

Make your own from your notes

A starter set is a head start, not your whole course. Your class notes, slides and textbook are what your teacher actually tests, so turn them into cards too.

Make cause-chain cards: front a human activity, back the sequence of effects.
Put a law or treaty name on the front and its purpose and year on the back.
Avoid long lists of statistics. Keep only the benchmark numbers your course asks for.
Add one card per case study you covered, with the main lesson on the back.

Generate cards from a topic or notes Turn a PDF into flashcards

AP Environmental Science flashcards: questions

Is APES math heavy?

Not very, but you should be comfortable with percentages, unit conversions and scientific notation. Calculations such as the rule of 70 and percent change are common.

Do I need to memorise laws and dates?

Know what each major law does and what problem it addressed. Years are useful for ordering, but the purpose is more important.

How do I study biogeochemical cycles?

Draw each cycle from memory, label reservoirs and the processes between them, and add a card on how human activity changes the flows.

Does this set cover the whole APES course?

No. It covers core concepts from the nine units. Add your own cards for the case studies and data skills your course emphasises.

Is this affiliated with the College Board?

No. It is an independent study aid that follows the published unit names.

Sources and review

These cards are an independent study aid, not official exam content, and are not affiliated with or endorsed by any exam body or publisher. They were written by hand and checked against the sources below on 2026-10-17. Always confirm details with your course materials and the current official documents.

College Board: AP Environmental Science course page — Checked the names and order of the nine units used for grouping; individual cards written from standard course content.
US EPA: Understanding Global Warming Potentials — Checked the 100-year GWP values for methane (27 to 30) and nitrous oxide (273) on this page.

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