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United States · College BoardSyllabus
Environmental Science syllabus, dot point by dot point
Every dot point in the United States Environmental Sciencesyllabus, with a focused answer for each one. Click any dot point for a worked explainer, past exam questions, and links to related dot points. Written by Claude Opus 4.8, Anthropic's latest AI.
Unit 1: The Living World: Ecosystems
Module overview →- What abiotic factors determine the distribution and productivity of aquatic biomes?Topic 1.3 Aquatic Biomes: describe the major freshwater and marine biomes and explain how abiotic factors such as salinity, depth, light, temperature and nutrients shape them.9 min answer →
- Why is only about ten percent of energy passed from one trophic level to the next?Topic 1.10 Energy Flow and the 10% Rule: explain how energy is lost between trophic levels, apply the 10% rule, and calculate energy transfer and ecological efficiency.10 min answer →
- How do food chains combine into food webs, and what happens when one species is removed?Topic 1.11 Food Chains and Food Webs: describe how food chains and food webs represent the flow of energy and matter, and predict the effects of changes to a food web.9 min answer →
- How do interactions between organisms shape the structure of an ecosystem?Topic 1.1 Introduction to Ecosystems: explain how species interactions, including predation, symbiosis and competition, shape ecosystems and influence the survival of organisms.9 min answer →
- How much energy do producers capture, and what determines the productivity of an ecosystem?Topic 1.8 Primary Productivity: define gross and net primary productivity, explain the factors that control them, and calculate net primary productivity from data.10 min answer →
- How do temperature and precipitation determine where the major terrestrial biomes occur?Topic 1.2 Terrestrial Biomes: describe the global distribution of the major terrestrial biomes and explain how temperature and precipitation determine the type of biome found in a region.9 min answer →
- How does carbon move between living organisms, the atmosphere, oceans and rocks?Topic 1.4 The Carbon Cycle: describe the major reservoirs and fluxes of the carbon cycle and explain how natural processes and human activities move carbon between them.10 min answer →
- How does water move between the atmosphere, land and oceans, and how do humans alter these flows?Topic 1.7 The Hydrologic (Water) Cycle: describe the processes of the water cycle and explain how human activities alter the storage and movement of water.9 min answer →
- How is atmospheric nitrogen converted into forms organisms can use, and how do humans alter this cycle?Topic 1.5 The Nitrogen Cycle: describe the steps of the nitrogen cycle and explain how nitrogen fixation, the role of bacteria and human activities move nitrogen between reservoirs.10 min answer →
- Why does the phosphorus cycle lack an atmospheric stage, and how does this make phosphorus a limiting nutrient?Topic 1.6 The Phosphorus Cycle: describe the phosphorus cycle, explain why it has no significant atmospheric component, and explain how phosphorus acts as a limiting nutrient and a pollutant.9 min answer →
- How is energy organized into feeding levels, and why does each level hold less energy than the one below?Topic 1.9 Trophic Levels: describe the trophic levels of an ecosystem and explain the roles of producers, consumers and decomposers in transferring energy and matter.9 min answer →
Unit 2: The Living World: Biodiversity
Module overview →- How does natural selection produce adaptations, and how do environmental changes drive new ones?Topic 2.6 Adaptations: explain how natural selection produces adaptations and how environmental change shifts which traits are favored over time.9 min answer →
- How do communities rebuild after disturbance, and what roles do pioneer and keystone species play?Topic 2.7 Ecological Succession: distinguish primary and secondary succession, describe how communities change over time, and explain the roles of pioneer, keystone and indicator species.9 min answer →
- What range of conditions can an organism survive, and how does this set the limits of where it can live?Topic 2.4 Ecological Tolerance: describe the range of tolerance of organisms and explain how tolerance limits determine the distribution and survival of species.9 min answer →
- What benefits do humans gain from ecosystems, and how does biodiversity loss threaten them?Topic 2.2 Ecosystem Services: describe the four categories of ecosystem services and explain how the disruption of ecosystems affects the services they provide.9 min answer →
- What are the levels of biodiversity, and why does greater diversity make ecosystems more resilient?Topic 2.1 Introduction to Biodiversity: describe the three levels of biodiversity and explain how genetic and species diversity contribute to ecosystem resilience.9 min answer →
- Why do larger islands closer to the mainland support more species, and what does this teach us about habitat fragments?Topic 2.3 Island Biogeography: explain how island size and distance from the mainland determine species richness, and apply the theory to habitat fragments.9 min answer →
- How do natural disturbances of different scales and timescales shape ecosystems?Topic 2.5 Natural Disruptions to Ecosystems: describe natural disruptions to ecosystems and explain their short-term and long-term effects on populations and biodiversity.9 min answer →
Unit 3: Populations
Module overview →- How can the shape of a population pyramid tell you whether a country will boom, hold steady, or shrink?Topic 3.5 Age Structure Diagrams: interpret age structure diagrams (population pyramids) to predict population growth, stability or decline.9 min answer →
- What sets the ceiling on how many organisms an environment can support, and what happens when a population shoots past it?Topic 3.3 Carrying Capacity: define carrying capacity, explain overshoot and dieback, and interpret population oscillations around the carrying capacity.10 min answer →
- Why does population growth first surge and then slow as a country industrializes?Topic 3.8 Demographic Transition: describe the four stages of the demographic transition model and explain how birth and death rates change as a country develops.10 min answer →
- Why does a raccoon thrive almost anywhere while a panda survives only where bamboo grows?Topic 3.1 Generalist and Specialist Species: distinguish generalist from specialist species and explain how a changing or stable environment favors each.9 min answer →
- What makes a human population grow, and how do birth, death and migration rates combine to set its growth rate?Topic 3.7 Human Population Dynamics: explain the factors that influence human population size and growth, and calculate growth rate from crude birth, death and migration rates.11 min answer →
- When does a population explode in a J-shaped curve, and when does it level off in an S?Topic 3.4 Population Growth and Resource Availability: compare exponential (J-curve) and logistic (S-curve) growth, link them to r- and K-selected species, and calculate growth rate and doubling time.11 min answer →
- Why do humans, songbirds and oysters each leave a differently shaped line on a survivorship graph?Topic 3.2 Survivorship Curves: interpret Type I, II and III survivorship curves and link each shape to a species' reproductive and life-history strategy.9 min answer →
- Why does a fertility rate of about 2.1 keep a population from growing or shrinking?Topic 3.6 Total Fertility Rate: define total fertility rate and replacement-level fertility, and explain the factors that raise or lower a country's TFR.10 min answer →
Unit 4: Earth Systems and Resources
Module overview →- What is the air made of, and why does temperature rise and fall as you climb through the atmosphere?Topic 4.4 Earth's Atmosphere: describe the composition of the atmosphere and the four main layers, and explain how temperature changes with altitude.9 min answer →
- Why is one side of a mountain range lush and the other a desert, and what does El Nino have to do with it?Topic 4.8 Earth's Geography and Climate: explain how geographic features such as mountains and proximity to water shape regional climate, including rain shadows and El Nino and La Nina.10 min answer →
- Why are the great deserts found near 30 degrees latitude and the rainforests at the equator?Topic 4.5 Global Wind Patterns: explain how uneven solar heating and the Coriolis effect drive atmospheric circulation cells and global wind belts.10 min answer →
- What drives the slow movement of Earth's plates, and why do earthquakes, volcanoes and mountains cluster where they meet?Topic 4.1 Plate Tectonics: explain how convection in the mantle drives plate movement and describe the three types of plate boundary and their landforms and hazards.10 min answer →
- Why does the mix of sand, silt and clay decide how well a soil holds water and grows crops?Topic 4.3 Soil Composition and Properties: describe soil texture using the soil triangle, and explain how particle size affects porosity, permeability, water-holding capacity and fertility.9 min answer →
- How does solid rock become living soil, and why is that soil so easily lost?Topic 4.2 Soil Formation and Erosion: explain how soil forms from weathered rock and organic matter, describe the soil horizons, and explain the causes and effects of soil erosion.10 min answer →
- Why do we have summer and winter, and why is it not simply because Earth is closer to the Sun?Topic 4.7 Solar Radiation and Earth's Seasons: explain how the tilt of Earth's axis and its orbit produce variations in insolation that cause the seasons.9 min answer →
- Where does the rain that falls on a hillside actually end up, and what decides how fast it gets there?Topic 4.6 Watersheds: define a watershed, describe the factors that affect its characteristics, and explain how land use changes runoff and water quality.9 min answer →
Unit 5: Land and Water Use
Module overview →- Can farming fish take the pressure off wild stocks, or does it just create new pollution problems?Topic 5.16 Aquaculture: describe aquaculture and explain its benefits and environmental costs compared with wild fishing.9 min answer →
- Why is removing every tree at once the cheapest way to log a forest but also the most damaging?Topic 5.2 Clearcutting: describe clearcutting and explain its environmental consequences for soil, water and ecosystems.9 min answer →
- How much of the planet does it take to support one person's lifestyle, and why do some people need far more than others?Topic 5.11 Ecological Footprints: define the ecological footprint, explain what it measures, and compare footprints between countries and lifestyles.9 min answer →
- How do tilling, fertilizing and grazing the land slowly wear it out?Topic 5.4 The Impact of Agricultural Practices: explain how tillage, fertilizer use, overgrazing and other farming practices degrade soil and water.10 min answer →
- What does digging minerals out of the ground do to the land and water around the mine?Topic 5.9 Impacts of Mining: compare surface and subsurface mining and explain their environmental consequences, including acid mine drainage and tailings.10 min answer →
- Why have so many fisheries collapsed, and how can fishing be made sustainable?Topic 5.8 Impacts of Overfishing: explain how overfishing depletes fish stocks, describe destructive fishing methods, and explain sustainable management.10 min answer →
- How can a farmer control pests with the least possible pesticide and still protect the crop?Topic 5.14 Integrated Pest Management: describe integrated pest management (IPM) and explain how it combines biological, cultural, mechanical and limited chemical control.9 min answer →
- What does it actually mean to use a resource sustainably, and how do we measure whether we are?Topic 5.12 Introduction to Sustainability: define sustainability and sustainable yield, and explain the indicators used to assess whether resource use is sustainable.9 min answer →
- Which way of watering crops wastes the least water, and why does irrigation sometimes ruin the soil it feeds?Topic 5.5 Irrigation Methods: compare the main irrigation methods and explain the problems of salinisation, waterlogging and aquifer depletion.10 min answer →
- Why does producing meat take so much more land, water and energy than producing the same amount of plant food?Topic 5.7 Meat Production Methods: compare free-range and feedlot (CAFO) meat production and explain the environmental costs of meat, including its high resource use.10 min answer →
- How can a city be built so that rainwater soaks in and stays clean instead of flooding the streets?Topic 5.13 Methods to Reduce Urban Runoff: describe methods such as permeable pavement, rain gardens, green roofs and retention ponds that reduce urban stormwater runoff.9 min answer →
- Why does spraying more pesticide often make the pest problem worse over time?Topic 5.6 Pest Control Methods: compare chemical and biological pest control and explain the pesticide treadmill and the evolution of pesticide resistance.10 min answer →
- How can we grow enough food while keeping the soil, water and biodiversity that farming depends on?Topic 5.15 Sustainable Agriculture: describe sustainable farming practices that conserve soil and water and maintain long-term productivity.10 min answer →
- How can we keep harvesting wood without destroying the forests that produce it?Topic 5.17 Sustainable Forestry: describe sustainable forestry practices that reduce deforestation while still supplying timber.9 min answer →
- How did new seeds, fertilizers and machines multiply crop yields, and what did that progress cost the environment?Topic 5.3 The Green Revolution: describe the methods and benefits of the Green Revolution and explain its environmental costs.9 min answer →
- Why do shared resources like fisheries and grazing land so often end up overused and ruined?Topic 5.1 The Tragedy of the Commons: explain how shared, unregulated resources tend to be overexploited, and describe solutions such as regulation and privatisation.9 min answer →
- How does turning land into a city change the way water, heat and pollution move through it?Topic 5.10 Urbanization: explain the environmental effects of urbanization, including impervious surfaces, runoff, the urban heat island, sprawl and saltwater intrusion.10 min answer →
Unit 6: Energy Resources and Consumption
Module overview →- Why does some energy come from one country but get burned in another?Topic 6.4 Distribution of Natural Energy Resources: explain why energy resources are unevenly distributed and the consequences of that uneven distribution.9 min answer →
- How can using energy more wisely cut both our bills and our impact?Topic 6.13 Energy Conservation: describe strategies for energy conservation and efficiency and explain how they reduce environmental impact.9 min answer →
- Can burning wood and crops be a clean way to make energy?Topic 6.7 Energy from Biomass: describe how biomass and biofuels are used for energy and evaluate their benefits and drawbacks.9 min answer →
- How do we turn buried coal, oil and gas into electricity, and what does it cost the environment?Topic 6.5 Fossil Fuels: explain how fossil fuels form and are used to generate electricity, and describe their environmental impacts, including cogeneration.10 min answer →
- What are the main fuels we burn, and what do we use each one for?Topic 6.3 Fuel Types and Uses: identify the major fuel types (coal, oil, natural gas, biomass) and describe their main uses and relative impacts.9 min answer →
- How can Earth's internal heat be used to make electricity and warm buildings?Topic 6.10 Geothermal Energy: describe how geothermal energy is captured and evaluate its benefits and drawbacks.9 min answer →
- Who uses the most energy in the world, and what do they use it for?Topic 6.2 Global Energy Consumption: describe patterns of global energy use and the factors, including development and population, that drive demand.9 min answer →
- How does flowing water make electricity, and what does a dam do to a river?Topic 6.9 Hydroelectric Power: describe how hydroelectric and tidal power generate electricity and evaluate their benefits and drawbacks.9 min answer →
- Can hydrogen be a clean fuel, and where does the hydrogen come from?Topic 6.11 Hydrogen Fuel Cell: explain how a hydrogen fuel cell works and evaluate its benefits and drawbacks.9 min answer →
- How does splitting atoms make electricity, and why is the waste so hard to deal with?Topic 6.6 Nuclear Power: explain how nuclear fission generates electricity and describe the benefits and risks, including radioactive waste and half-life.10 min answer →
- Which energy sources run out, and which keep being replenished?Topic 6.1 Renewable and Nonrenewable Resources: distinguish renewable from nonrenewable energy resources and explain why the distinction matters for sustainability.9 min answer →
- How can we turn sunlight into electricity and heat, and what are the limits?Topic 6.8 Solar Energy: describe how solar energy is captured using photovoltaic, active and passive systems and evaluate its benefits and drawbacks.9 min answer →
- How do wind turbines make electricity, and what are the trade-offs?Topic 6.12 Wind Energy: describe how wind turbines generate electricity and evaluate the benefits and drawbacks of wind power.9 min answer →
Unit 7: Atmospheric Pollution
Module overview →- How does burning coal and fuel turn rain acidic, and what does that acid do downwind?Topic 7.7 Acid Rain: explain how acid rain forms from sulfur and nitrogen oxides and describe its environmental impacts.10 min answer →
- Where do the carbon dioxide and tiny particles in the air come from, and why does particle size matter?Topic 7.4 Atmospheric CO2 and Particulates: describe the natural and human sources of atmospheric carbon dioxide and particulate matter and their effects.9 min answer →
- Why can the air inside a home be more polluted than the air outside?Topic 7.5 Indoor Air Pollutants: identify the major indoor air pollutants and their sources and explain why indoor air pollution is a serious health risk.9 min answer →
- Where does air pollution come from, and what is the difference between pollution made directly and pollution made in the air?Topic 7.1 Introduction to Air Pollution: identify the major air pollutants and their sources and distinguish primary from secondary pollutants.9 min answer →
- How can unwanted sound harm people and wildlife, and how is it measured?Topic 7.8 Noise Pollution: identify the sources of noise pollution and describe its effects on humans and wildlife.9 min answer →
- Why does a brown haze form over cities on hot, sunny days?Topic 7.2 Photochemical Smog: explain how photochemical smog forms from nitrogen oxides, volatile organic compounds and sunlight, and describe its impacts.9 min answer →
- How can we clean up the air we have already polluted, and stop pollution at the source?Topic 7.6 Reduction of Air Pollutants: describe methods used to reduce air pollution, including regulation, scrubbers, catalytic converters and cleaner fuels.9 min answer →
- Why does a layer of warm air sometimes trap pollution close to the ground?Topic 7.3 Thermal Inversion: explain how a thermal inversion forms and why it traps air pollution near the ground.9 min answer →
Unit 8: Aquatic and Terrestrial Pollution
Module overview →- Why do top predators end up with far higher levels of a toxin than the water they live in?Topic 8.8 Bioaccumulation and Biomagnification: distinguish bioaccumulation from biomagnification and explain how toxins concentrate up food chains.10 min answer →
- How does the harm from a chemical change as the dose goes up, and is there always a safe level?Topic 8.13 Dose Response Curve: interpret a dose-response curve and explain the difference between threshold and linear (non-threshold) responses.9 min answer →
- How can a chemical at tiny doses scramble an animal's hormones and reproduction?Topic 8.3 Endocrine Disruptors: explain what endocrine disruptors are and how they affect organisms by interfering with hormones.9 min answer →
- How does fertilizer runoff end up suffocating the fish in a lake?Topic 8.5 Eutrophication: explain how nutrient pollution causes eutrophication and oxygen depletion in aquatic ecosystems.10 min answer →
- How does pollution ripple through an ecosystem to harm species that never touched it directly?Topic 8.2 Human Impacts on Ecosystems: explain how pollution and other human activities disrupt ecosystems and harm organisms.9 min answer →
- Why does draining a swamp or clearing a mangrove cost us far more than the land we gain?Topic 8.4 Human Impacts on Wetlands and Mangroves: describe the ecosystem services of wetlands and mangroves and the consequences of destroying them.9 min answer →
- How do scientists measure how poisonous a chemical is?Topic 8.12 Lethal Dose 50% (LD50): explain what LD50 measures and how it is used to compare the toxicity of substances.9 min answer →
- Why do some banned chemicals still turn up in animals decades later and far from where they were used?Topic 8.7 Persistent Organic Pollutants (POPs): describe the properties of persistent organic pollutants and explain why they are especially harmful.9 min answer →
- How does pollution make people sick, and how do diseases spread through dirty water?Topic 8.14 Pollution and Human Health: describe how pollutants and pathogens affect human health and how infectious diseases spread through the environment.10 min answer →
- What has to happen to dirty water before it can safely return to a river?Topic 8.11 Sewage Treatment: describe the stages of sewage treatment and explain how they reduce water pollution.9 min answer →
- Where does our rubbish actually go, and what does it do once it gets there?Topic 8.9 Solid Waste Disposal: describe the main methods of solid waste disposal and their environmental impacts.10 min answer →
- Why is it easy to fine a factory pipe but hard to stop pollution from a whole city's runoff?Topic 8.1 Sources of Pollution: distinguish point and non-point sources of pollution and identify major types of pollutants.9 min answer →
- How can hot water from a power plant harm a river without adding any chemicals?Topic 8.6 Thermal Pollution: explain how thermal pollution occurs and why warmer water harms aquatic ecosystems.9 min answer →
- How can we cut the amount of waste we make before it ever reaches a landfill?Topic 8.10 Waste Reduction Methods: describe methods of reducing waste, including the waste hierarchy, recycling and composting.9 min answer →
Unit 9: Global Change
Module overview →- What pushes a species toward extinction, and how do we pull it back?Topic 9.9 Endangered Species: explain the factors that make species vulnerable to extinction and describe how endangered species are protected.9 min answer →
- What changes as the planet warms, and how do feedback loops make it worse?Topic 9.5 Global Climate Change: describe the evidence and effects of global climate change and explain the role of positive feedback loops.10 min answer →
- What are the big human pressures driving species loss, and why does losing biodiversity matter?Topic 9.10 Human Impacts on Biodiversity: identify the major human causes of biodiversity loss (HIPPCO) and explain why declining biodiversity matters.10 min answer →
- Why are greenhouse gases rising, and which human activities are to blame?Topic 9.4 Increases in the Greenhouse Gases: identify the human activities that increase greenhouse gases and explain why their concentrations are rising.9 min answer →
- Why can a species that is harmless at home wreck an ecosystem somewhere new?Topic 9.8 Invasive Species: explain what makes a species invasive and describe the impacts of invasive species and how they are managed.9 min answer →
- How does carbon dioxide make the sea more acidic, and why does that dissolve shells?Topic 9.7 Ocean Acidification: explain how rising carbon dioxide acidifies the ocean and describe the effects on marine organisms.9 min answer →
- What does a warmer ocean do to coral, sea level and marine life?Topic 9.6 Ocean Warming: explain how the ocean absorbs heat and describe the effects of ocean warming on marine ecosystems and sea level.9 min answer →
- How did the world manage to start healing the ozone layer?Topic 9.2 Reducing Ozone Depletion: describe the strategies and international agreements used to reduce ozone depletion and how the ozone layer is recovering.9 min answer →
- What punched a hole in the ozone layer, and why does it matter?Topic 9.1 Stratospheric Ozone Depletion: explain how CFCs deplete stratospheric ozone and describe the consequences of a thinner ozone layer.10 min answer →
- How do gases in the air keep the planet warm, and which gases matter most?Topic 9.3 The Greenhouse Effect: explain the greenhouse effect, identify the major greenhouse gases, and distinguish the natural effect from the enhanced effect.10 min answer →