AP Environmental Science

Enduring Understanding (ERT-1): Ecosystems are the result of biotic and abiotic interactions.

Learning Objective ERT-1.A: Explain how the availability of resources influences species interactions.

• ERT-1.A.1 In a predator-prey relationship, the predator is an organism that eats another organism (the prey).
• ERT-1.A.2 Symbiosis is a close and long-term interaction between two species in an ecosystem. Types of symbiosis include mutualism, commensalism, and parasitism.
• ERT-1.A.3 Competition can occur within or between species in an ecosystem where there are limited resources. Resource partitioning—using the resources in different ways, places, or at different times—can reduce the negative impact of competition on survival.

Enduring Understanding (ERT-1): Ecosystems are the result of biotic and abiotic interactions.

Learning Objective ERT-1.B: Describe the global distribution and principal environmental aspects of terrestrial biomes.

• ERT-1.B.1 A biome contains characteristic communities of plants and animals that result from, and are adapted to, its climate.
• ERT-1.B.2 Major terrestrial biomes include taiga, temperate rainforests, temperate seasonal forests, tropical rainforests, shrubland, temperate grassland, savanna, desert, and tundra.
• ERT-1.B.3 The global distribution of nonmineral terrestrial natural resources, such as water and trees for lumber, varies because of some combination of climate, geography, latitude and altitude, nutrient availability, and soil.
• ERT-1.B.4 The worldwide distribution of biomes is dynamic; the distribution has changed in the past and may again shift as a result of global climate changes.

Enduring Understanding (ERT-1): Ecosystems are the result of biotic and abiotic interactions.

Learning Objective ERT-1.C: Describe the global distribution and principal environmental aspects of aquatic biomes.

• ERT-1.C.1 Freshwater biomes include streams, rivers, ponds, and lakes. These freshwater biomes are a vital resource for drinking water.
• ERT-1.C.2 Marine biomes include oceans, coral reefs, marshland, and estuaries. Algae in marine biomes supply a large portion of the Earth's oxygen, and also take in carbon dioxide from the atmosphere.
• ERT-1.C.3 The global distribution of nonmineral marine natural resources, such as different types of fish, varies because of some combination of salinity, depth, turbidity, nutrient availability, and temperature.

Enduring Understanding (ERT-1): Ecosystems are the result of biotic and abiotic interactions.

Learning Objective ERT-1.D: Explain the steps and reservoir interactions in the carbon cycle.

• ERT-1.D.1 The carbon cycle is the movement of atoms and molecules containing the element carbon between sources and sinks.
• ERT-1.D.2 Some of the reservoirs in which carbon compounds occur in the carbon cycle hold those compounds for long periods of time, while some hold them for relatively short periods of time.
• ERT-1.D.3 Carbon cycles between photosynthesis and cellular respiration in living things.
• ERT-1.D.4 Plant and animal decomposition have led to the storage of carbon over millions of years. The burning of fossil fuels quickly moves that stored carbon into atmospheric carbon, in the form of carbon dioxide.

Enduring Understanding (ERT-1): Ecosystems are the result of biotic and abiotic interactions.

Learning Objective ERT-1.E: Explain the steps and reservoir interactions in the nitrogen cycle.

• ERT-1.E.1 The nitrogen cycle is the movement of atoms and molecules containing the element nitrogen between sources and sinks.
• ERT-1.E.2 Most of the reservoirs in which nitrogen compounds occur in the nitrogen cycle hold those compounds for relatively short periods of time.
• ERT-1.E.3 Nitrogen fixation is the process in which atmospheric nitrogen is converted into a form of nitrogen (primarily ammonia) that is available for uptake by plants and that can be synthesized into plant tissue.
• ERT-1.E.4 The atmosphere is the major reservoir of nitrogen.

Enduring Understanding (ERT-1): Ecosystems are the result of biotic and abiotic interactions.

Learning Objective ERT-1.F: Explain the steps and reservoir interactions in the phosphorus cycle.

• ERT-1.F.1 The phosphorus cycle is the movement of atoms and molecules containing the element phosphorus between sources and sinks.
• ERT-1.F.2 The major reservoirs of phosphorus in the phosphorus cycle are rock and sediments that contain phosphorus-bearing minerals.
• ERT-1.F.3 There is no atmospheric component in the phosphorus cycle, and the limitations this imposes on the return of phosphorus from the ocean to land make phosphorus naturally scarce in aquatic and many terrestrial ecosystems. In undisturbed ecosystems, phosphorus is the limiting factor in biological systems.

Enduring Understanding (ERT-1): Ecosystems are the result of biotic and abiotic interactions.

Learning Objective ERT-1.G: Explain the steps and reservoir interactions in the hydrologic cycle.

• ERT-1.G.1 The hydrologic cycle, which is powered by the sun, is the movement of water in its various solid, liquid, and gaseous phases between sources and sinks.
• ERT-1.G.2 The oceans are the primary reservoir of water at the Earth's surface, with ice caps and groundwater acting as much smaller reservoirs.

Enduring Understanding (ENG-1): Energy can be converted from one form to another.

Learning Objective ENG-1.A: Explain how solar energy is acquired and transferred by living organisms.

• ENG-1.A.1 Primary productivity is the rate at which solar energy (sunlight) is converted into organic compounds via photosynthesis over a unit of time.
• ENG-1.A.2 Gross primary productivity is the total rate of photosynthesis in a given area.
• ENG-1.A.3 Net primary productivity is the rate of energy storage by photosynthesizers in a given area, after subtracting the energy lost to respiration.
• ENG-1.A.4 Productivity is measured in units of energy per unit area per unit time (e.g., $\text{kcal/m}^2\text{/yr}$).
• ENG-1.A.5 Most red light is absorbed in the upper 1m of water, and blue light only penetrates deeper than 100m in the clearest water. This affects photosynthesis in aquatic ecosystems, whose photosynthesizers have adapted mechanisms to address the lack of visible light.

Enduring Understanding (ENG-1): Energy can be converted from one form to another.

Learning Objective ENG-1.B: Explain how energy flows and matter cycles through trophic levels.

• ENG-1.B.1 All ecosystems depend on a continuous inflow of high-quality energy in order to maintain their structure and function of transferring matter between the environment and organisms via biogeochemical cycles.
• ENG-1.B.2 Biogeochemical cycles are essential for life and each cycle demonstrates the conservation of matter.
• ENG-1.B.3 In terrestrial and near-surface marine communities, energy flows from the sun to producers in the lowest trophic levels and then upward to higher trophic levels.

Enduring Understanding (ENG-1): Energy can be converted from one form to another.

Learning Objective ENG-1.C: Determine how the energy decreases as it flows through ecosystems.

• ENG-1.C.1 The 10% rule approximates that in the transfer of energy from one trophic level to the next, only about 10% of the energy is passed on.
• ENG-1.C.2 The loss of energy that occurs when energy moves from lower to higher trophic levels can be explained through the laws of thermodynamics.

Enduring Understanding (ENG-1): Energy can be converted from one form to another.

Learning Objective ENG-1.D: Describe food chains and food webs, and their constituent members by trophic level.

• ENG-1.D.1 A food web is a model of an interlocking pattern of food chains that depicts the flow of energy and nutrients in two or more food chains.
• ENG-1.D.2 Positive and negative feedback loops can each play a role in food webs. When one species is removed from or added to a specific food web, the rest of the food web can be affected.

Enduring Understanding (ERT-2): Ecosystems have structure and diversity that change over time.

Learning Objective ERT-2.A: Explain levels of biodiversity and their importance to ecosystems.

• ERT-2.A.1 Biodiversity in an ecosystem includes genetic, species, and habitat diversity.
• ERT-2.A.2 The more genetically diverse a population is, the better it can respond to environmental stressors. Additionally, a population bottleneck can lead to a loss of genetic diversity.
• ERT-2.A.3 Ecosystems that have a larger number of species are more likely to recover from disruptions.
• ERT-2.A.4 Loss of habitat leads to a loss of specialist species, followed by a loss of generalist species. It also leads to reduced numbers of species that have large territorial requirements.
• ERT-2.A.5 Species richness refers to the number of different species found in an ecosystem.

Enduring Understanding (ERT-2): Ecosystems have structure and diversity that change over time.

Learning Objective ERT-2.B: Describe ecosystem services.

• ERT-2.B.1 There are four categories of ecosystem services: provisioning, regulating, cultural, and supporting.

Learning Objective ERT-2.C: Describe the results of human disruptions to ecosystem services.

• ERT-2.C.1 Anthropogenic activities can disrupt ecosystem services, potentially resulting in economic and ecological consequences.

Enduring Understanding (ERT-2): Ecosystems have structure and diversity that change over time.

Learning Objective ERT-2.D: Describe island biogeography.

• ERT-2.D.1 Island biogeography is the study of the ecological relationships and distribution of organisms on islands, and of these organisms' community structures.
• ERT-2.D.2 Islands have been colonized in the past by new species arriving from elsewhere.

Learning Objective ERT-2.E: Describe the role of island biogeography in evolution.

• ERT-2.E.1 Many island species have evolved to be specialists versus generalists because of the limited resources, such as food and territory, on most islands. The long-term survival of specialists may be jeopardized if and when invasive species, typically generalists, are introduced and outcompete the specialists.

Enduring Understanding (ERT-2): Ecosystems have structure and diversity that change over time.

Learning Objective ERT-2.F: Describe ecological tolerance.

• ERT-2.F.1 Ecological tolerance refers to the range of conditions, such as temperature, salinity, flow rate, and sunlight that an organism can endure before injury or death results.
• ERT-2.F.2 Ecological tolerance can apply to individuals and to species.

Enduring Understanding (ERT-2): Ecosystems have structure and diversity that change over time.

Learning Objective ERT-2.G: Explain how natural disruptions, both short- and long-term, impact an ecosystem.

• ERT-2.G.1 Natural disruptions to ecosystems have environmental consequences that may, for a given occurrence, be as great as, or greater than, many human-made disruptions.
• ERT-2.G.2 Earth system processes operate on a range of scales in terms of time. Processes can be periodic, episodic, or random.
• ERT-2.G.3 Earth's climate has changed over geological time for many reasons.
• ERT-2.G.4 Sea level has varied significantly as a result of changes in the amount of glacial ice on Earth over geological time.
• ERT-2.G.5 Major environmental change or upheaval commonly results in large swathes of habitat changes.
• ERT-2.G.6 Wildlife engages in both short- and long-term migration for a variety of reasons, including natural disruptions.

Enduring Understanding (ERT-2): Ecosystems have structure and diversity that change over time.

Learning Objective ERT-2.H: Describe how organisms adapt to their environment.

• ERT-2.H.1 Organisms adapt to their environment over time, both in short- and long-term scales, via incremental changes at the genetic level.
• ERT-2.H.2 Environmental changes, either sudden or gradual, may threaten a species' survival, requiring individuals to alter behaviors, move, or perish.

Enduring Understanding (ERT-2): Ecosystems have structure and diversity that change over time.

Learning Objective ERT-2.I: Describe ecological succession.

• ERT-2.I.1 There are two main types of ecological succession: primary and secondary succession.
• ERT-2.I.2 A keystone species in an ecosystem is a species whose activities have a particularly significant role in determining community structure.
• ERT-2.I.3 An indicator species is a plant or animal that, by its presence, abundance, scarcity, or chemical composition, demonstrates that some distinctive aspect of the character or quality of an ecosystem is present.

Learning Objective ERT-2.J: Describe the effect of ecological succession on ecosystems.

• ERT-2.J.1 Pioneer members of an early successional species commonly move into unoccupied habitat and over time adapt to its particular conditions, which may result in the origin of new species.
• ERT-2.J.2 Succession in a disturbed ecosystem will affect the total biomass, species richness, and net productivity over time.

Enduring Understanding (ERT-3): Populations change over time in reaction to a variety of factors.

Learning Objective ERT-3.A: Identify differences between generalist and specialist species.

• ERT-3.A.1 Specialist species tend to be advantaged in habitats that remain constant, while generalist species tend to be advantaged in habitats that are changing.

Enduring Understanding (ERT-3): Populations change over time in reaction to a variety of factors.

Learning Objective ERT-3.C: Explain survivorship curves.

• ERT-3.C.1 A survivorship curve is a line that displays the relative survival rates of a cohort—a group of individuals of the same age—in a population, from birth to the maximum age reached by any one cohort member. There are Type I, Type II, and Type III curves.
• ERT-3.C.2 Survivorship curves differ for K-selected and r-selected species, with K-selected species typically following a Type I or Type II curve and r-selected species following a Type III curve.

Enduring Understanding (ERT-3): Populations change over time in reaction to a variety of factors.

Learning Objective ERT-3.D: Describe carrying capacity.

• ERT-3.D.1 When a population exceeds its carrying capacity (carrying capacity can be denoted as K), overshoot occurs. There are environmental impacts of population overshoot, including resource depletion.

Learning Objective ERT-3.E: Describe the impact of carrying capacity on ecosystems.

• ERT-3.E.1 A major ecological effect of population overshoot is dieback of the population (often severe to catastrophic) because the lack of available resources leads to famine, disease, and/or conflict.

Enduring Understanding (EIN-1): Human populations change in reaction to a variety of factors, including social and cultural factors.

Learning Objective EIN-1.A: Explain age structure diagrams.

• EIN-1.A.1 Population growth rates can be interpreted from age structure diagrams by the shape of the structure.
• EIN-1.A.2 A rapidly growing population will, as a rule, have a higher proportion of younger people compared to stable or declining populations.

Enduring Understanding (EIN-1): Human populations change in reaction to a variety of factors, including social and cultural factors.

Learning Objective EIN-1.B: Explain factors that affect total fertility rate in human populations.

• EIN-1.B.1 Total fertility rate (TFR) is affected by the age at which females have their first child, educational opportunities for females, access to family planning, and government acts and policies.
• EIN-1.B.2 If fertility rate is at replacement levels, a population is considered relatively stable.
• EIN-1.B.3 Factors associated with infant mortality rates include whether mothers have access to good healthcare and nutrition. Changes in these factors can lead to changes in infant mortality rates over time.

Enduring Understanding (EIN-1): Human populations change in reaction to a variety of factors, including social and cultural factors.

Learning Objective EIN-1.C.1: Explain how human populations experience growth and decline.

• EIN-1.C.1 Birth rates, infant mortality rates, and overall death rates, access to family planning, access to good nutrition, access to education, and postponement of marriage all affect whether a human population is growing or declining.
• EIN-1.C.2 Factors limiting global human population include the Earth's carrying capacity and the basic factors that limit human population growth as set forth by Malthusian theory.
• EIN-1.C.3 Population growth can be affected by both density-independent factors, such as major storms, fires, heat waves, or droughts, and density-dependent factors, such as access to clean water and air, food availability, disease transmission, or territory size.
• EIN-1.C.4 The rule of 70 states that dividing the number 70 by the percentage population growth rate approximates the population's doubling time.

Enduring Understanding (EIN-1): Human populations change in reaction to a variety of factors, including social and cultural factors.

Learning Objective EIN-1.D: Define the demographic transition.

• EIN-1.D.1 The demographic transition refers to the transition from high to lower birth and death rates in a country or region as development occurs and that country moves from a pre-industrial to an industrialized economic system. This transition is typically demonstrated through a four-stage demographic transition model (DTM).
• EIN-1.D.2 Characteristics of developing countries include higher infant mortality rates and more children in the workforce than developed countries.

Enduring Understanding (ERT-4): Earth's systems interact, resulting in a state of balance over time.

Learning Objective ERT-4.A: Describe the geological changes and events that occur at convergent, divergent, and transform plate boundaries.

• ERT-4.A.1 Convergent boundaries can result in the creation of mountains, island arcs, earthquakes, and volcanoes.
• ERT-4.A.2 Divergent boundaries can result in seafloor spreading, rift valleys, volcanoes, and earthquakes.
• ERT-4.A.3 Transform boundaries can result in earthquakes.
• ERT-4.A.4 Maps that show the global distribution of plate boundaries can be used to determine the location of volcanoes, island arcs, earthquakes, hot spots, and faults.
• ERT-4.A.5 An earthquake occurs when stress overcomes a locked fault, releasing stored energy.

Enduring Understanding (ERT-4): Earth's systems interact, resulting in a state of balance over time.

Learning Objective ERT-4.B: Describe the characteristics and formation of soil.

• ERT-4.B.1 Soils are formed when parent material is weathered, transported, and deposited.
• ERT-4.B.2 Soils are generally categorized by horizons based on their composition and organic material.
• ERT-4.B.3 Soils can be eroded by winds or water. Protecting soils can protect water quality as soils effectively filter and clean water that moves through them.

Enduring Understanding (ERT-4): Earth's systems interact, resulting in a state of balance over time.

Learning Objective ERT-4.C: Describe similarities and differences between properties of different soil types.

• ERT-4.C.1 Water holding capacity—the total amount of water soil can hold—varies with different soil types. Water retention contributes to land productivity and fertility of soils.
• ERT-4.C.2 The particle size and composition of each soil horizon can affect the porosity, permeability, and fertility of the soil.
• ERT-4.C.3 There are a variety of methods to test the chemical, physical, and biological properties of soil that can aid in a variety of decisions, such as irrigation and fertilizer requirements.
• ERT-4.C.4 A soil texture triangle is a diagram that allows for the identification and comparison of soil types based on their percentage of clay, silt, and sand.

Enduring Understanding (ERT-4): Earth's systems interact, resulting in a state of balance over time.

Learning Objective ERT-4.D: Describe the structure and composition of the Earth's atmosphere.

• ERT-4.D.1 The atmosphere is made up of major gases, each with its own relative abundance.
• ERT-4.D.2 The layers of the atmosphere are based on temperature gradients and include the troposphere, stratosphere, mesosphere, thermosphere, and exosphere.

Enduring Understanding (ERT-4): Earth's systems interact, resulting in a state of balance over time.

Learning Objective ERT-4.E: Explain how environmental factors can result in atmospheric circulation.

• ERT-4.E.1 Global wind patterns primarily result from the most intense solar radiation arriving at the equator, resulting in density differences and the Coriolis effect.

Enduring Understanding (ERT-4): Earth's systems interact, resulting in a state of balance over time.

Learning Objective ERT-4.F: Describe the characteristics of a watershed.

• ERT-4.F.1 Characteristics of a given watershed include its area, length, slope, soil, vegetation types, and divides with adjoining watersheds.

Enduring Understanding (ENG-2): Most of the Earth's atmospheric processes are driven by input of energy from the sun.

Learning Objective ENG-2.A: Explain how the sun's energy affects the Earth's surface.

• ENG-2.A.1 Incoming solar radiation (insolation) is the Earth's main source of energy and is dependent on season and latitude.
• ENG-2.A.2 The angle of the sun's rays determines the intensity of the solar radiation. Due to the shape of the Earth, the latitude that is directly horizontal to the solar radiation receives the most intensity.
• ENG-2.A.3 The highest solar radiation per unit area is received at the equator and decreases toward the poles.
• ENG-2.A.4 The solar radiation received at a location on the Earth's surface varies seasonally, with the most radiation received during the location's longest summer day and the least on the shortest winter day.
• ENG-2.A.5 The tilt of Earth's axis of rotation causes the Earth's seasons and the number of hours of daylight in a particular location on the Earth's surface.

Enduring Understanding (ENG-2): Most of the Earth's atmospheric processes are driven by input of energy from the sun.

Learning Objective ENG-2.B: Describe how the Earth's geography affects weather and climate.

• ENG-2.B.1 Weather and climate are affected not only by the sun's energy but by geologic and geographic factors, such as mountains and ocean temperature.
• ENG-2.B.2 A rain shadow is a region of land that has become drier because a higher elevation area blocks precipitation from reaching the land.

Enduring Understanding (ENG-2): Most of the Earth's atmospheric processes are driven by input of energy from the sun.

Learning Objective ENG-2.C: Describe the environmental changes and effects that result from El Niño or La Niña events (El Niño–Southern Oscillation).

• ENG-2.C.1 El Niño and La Niña are phenomena associated with changing ocean surface temperatures in the Pacific Ocean. These phenomena can cause global changes to rainfall, wind, and ocean circulation patterns.
• ENG-2.C.2 El Niño and La Niña are influenced by geological and geographic factors and can affect different locations in different ways.

Enduring Understanding (EIN-2): When humans use natural resources, they alter natural systems.

Learning Objective EIN-2.A: Explain the concept of the tragedy of the commons.

• EIN-2.A.1 The tragedy of the commons suggests that individuals will use shared resources in their own self-interest rather than in keeping with the common good, thereby depleting the resources.

Enduring Understanding (EIN-2): When humans use natural resources, they alter natural systems.

Learning Objective EIN-2.B: Describe the effect of clearcutting on forests.

• EIN-2.B.1 Clearcutting can be economically advantageous but leads to soil erosion, increased soil and stream temperatures, and flooding.
• EIN-2.B.2 Forests contain trees that absorb pollutants and store carbon dioxide. The cutting and burning of trees releases carbon dioxide and contributes to climate change.

Enduring Understanding (EIN-2): When humans use natural resources, they alter natural systems.

Learning Objective EIN-2.C: Describe changes in agricultural practices.

• EIN-2.C.1 The Green Revolution started a shift to new agricultural strategies and practices in order to increase food production, with both positive and negative results. Some of these strategies and methods are mechanization, genetically modified organisms (GMOs), fertilization, irrigation, and the use of pesticides.
• EIN-2.C.2 Mechanization of farming can increase profits and efficiency for farms. It can also increase reliance on fossil fuels.

Enduring Understanding (EIN-2): When humans use natural resources, they alter natural systems.

Learning Objective EIN-2.D: Describe agricultural practices that cause environmental damage.

• EIN-2.D.1 Agricultural practices that can cause environmental damage include tilling, slash-and-burn farming, and the use of fertilizers.

Enduring Understanding (EIN-2): When humans use natural resources, they alter natural systems.

Learning Objective EIN-2.E: Describe different methods of irrigation.

• EIN-2.E.1 The largest human use of freshwater is for irrigation (70%).
• EIN-2.E.2 Types of irrigation include drip irrigation, flood irrigation, furrow irrigation, drip irrigation, and spray irrigation.

Learning Objective EIN-2.F: Describe the benefits and drawbacks of different methods of irrigation.

• EIN-2.F.1 Waterlogging occurs when too much water is left to sit in the soil, which raises the water table of groundwater and inhibits plants' ability to absorb oxygen through their roots.
• EIN-2.F.2 Furrow irrigation involves cutting furrows between crop rows and filling them with water. This system is inexpensive, but about 1/3 of the water is lost to evaporation and runoff.
• EIN-2.F.3 Flood irrigation involves flooding an agricultural field with water. This system sees about 20% of the water lost to evaporation and runoff. This can also lead to waterlogging of the soil.
• EIN-2.F.4 Spray irrigation involves pumping ground water into spray nozzles across an agricultural field. This system is more efficient than flood and furrow irrigation, with only 1/4 or less of the water lost to evaporation or runoff. However, spray systems are more expensive than flood and furrow irrigation, and also requires energy to run.
• EIN-2.F.5 Drip irrigation uses perforated hoses to release small amounts of water to plant roots. This system is the most efficient, with only about 5% of water lost to evaporation and runoff. However, this system is expensive and so is not often used.
• EIN-2.F.6 Salinization occurs when the salts in groundwater remain in the soil after the water evaporates. Over time, salinization can make soil toxic to plants.
• EIN-2.F.7 Aquifers can be severely depleted if overused for agricultural irrigation, as has happened to the Ogallala Aquifer in the central United States.

Enduring Understanding (EIN-2): When humans use natural resources, they alter natural systems.

Learning Objective EIN-2.G: Describe the benefits and drawbacks of different methods of pest control.

• EIN-2.G.1 One consequence of using common pest-control methods such as pesticides, herbicides, fungicides, rodenticides, and insecticides is that organisms can become resistant to them through artificial selection. Pest control decreases crop damage by pest and increases crop yields.
• EIN-2.G.2 Crops can be genetically engineered to increase their resistance to pests and diseases. However, using genetically engineered crops in planting or other ways can lead to loss of genetic diversity of that particular crop.

Enduring Understanding (EIN-2): When humans use natural resources, they alter natural systems.

Learning Objective EIN-2.H: Identify different methods of meat production.

• EIN-2.H.1 Methods of meat production include concentrated animal feeding operations (CAFOs), also called feedlots, and free-range grazing.

Learning Objective EIN-2.I: Describe the benefits and drawbacks of different methods of meat production.

• EIN-2.I.1 Meat production is less efficient than agriculture; it takes approximately 20 times more land to produce the same amount of calories from meat as from plants.
• EIN-2.I.2 Concentrated animal feeding operation (CAFOs) are used as a way to quickly get livestock ready for slaughter. They tend to be crowded, and animals are fed grains or feed that are not as suitable as grass. Additionally, feedlots generate a large amount of organic waste, which can contaminate ground and surface water. The use of feedlots are less expensive than other methods, which can keep costs to consumers down.
• EIN-2.I.3 Free range grazing allows animals to graze on grass during their entire lifecycle. Meat from free range animals tends to be free from antibiotics and other chemicals used in feedlots. Organic waste from these animals acts as fertilizer. Free range grazing requires large areas of land and the meat produced is more expensive for consumers.
• EIN-2.I.4 Overgrazing occurs when too many animals feed on a particular area of land. Overgrazing causes loss of vegetation, which leads to soil erosion.
• EIN-2.I.5 Overgrazing can cause desertification. Desertification is the degradation of low precipitation regions toward being increasingly arid until they become deserts.
• EIN-2.I.6 Less consumption of meat could reduce $\text{CO}_2$, methane, and $\text{N}_2\text{O}$ emissions; conserve water; reduce the use of antibiotics and growth hormones; and improve topsoil.

Enduring Understanding (EIN-2): When humans use natural resources, they alter natural systems.

Learning Objective EIN-2.J: Describe causes of and problems related to overfishing.

• EIN-2.J.1 Overfishing has led to the extreme scarcity of some fish species, which can lessen biodiversity in aquatic systems and harm people who depend on fishing for food and commerce.

Enduring Understanding (EIN-2): When humans use natural resources, they alter natural systems.

Learning Objective EIN-2.K: Describe natural resource extraction through mining.

• EIN-2.K.1 As the more accessible ores are mined to depletion, mining operations are forced to access lower grade ores. Accessing these ores requires increased use of resources that can cause increased waste and pollution.
• EIN-2.K.2 Surface mining is the removal of large portions of soil and rock, called overburden, in order to access the ore underneath. An example is strip mining, which removes the vegetation from an area, making the area more susceptible to erosion.

Learning Objective EIN-2.L: Describe ecological and economic impacts of natural resource extraction through mining.

• EIN-2.L.1 Mining wastes include the soil and rocks that are moved to gain access to the ore and the waste, called slag and tailings that remain when the minerals have been removed from the ore. Mining helps to provide low cost energy and material necessary to make products. The mining of coal can destroy habitats, contaminate ground water, and release dust particles and methane.
• EIN-2.L.2 As coal reserves get smaller, due to a lack of easily accessible reserves, it becomes necessary to access coal through subsurface mining, which is very expensive.

Enduring Understanding (EIN-2): When humans use natural resources, they alter natural systems.

Learning Objective EIN-2.M: Describe the effects of urbanization on the environment.

• EIN-2.M.1 Urbanization can lead to depletion of resources and saltwater intrusion in the hydrologic cycle.
• EIN-2.M.2 Urbanization, through the burning of fossil fuels and landfills, affects the carbon cycle by increasing the amount of carbon dioxide in the atmosphere.
• EIN-2.M.3 Impervious surfaces are human-made structures—such as roads, buildings, sidewalks, and parking lots—that do not allow water to reach the soil, leading to flooding.
• EIN-2.M.4 Urban sprawl is the change in population distribution from high population density areas to low density suburbs that spread into rural lands, leading to potential environmental problems.

Enduring Understanding (EIN-2): When humans use natural resources, they alter natural systems.

Learning Objective EIN-2.N: Explain the variables measured in an ecological footprint.

• EIN-2.N.1 Ecological footprints compare resource demands and waste production required for an individual or a society.

Enduring Understanding (STB-1): Humans can mitigate their impact on land and water resources through sustainable use.

Learning Objective STB-1.A: Explain the concept of sustainability.

• STB-1.A.1 Sustainability refers to humans living on Earth and their use of resources without depletion of the resources for future generations. Environmental indicators that can guide humans to sustainability include biological diversity, food production, average global surface temperatures and $\text{CO}_2$ concentrations, human population, and resource depletion.
• STB-1.A.2 Sustainable yield is the amount of a renewable resource that can be taken without reducing the available supply.

Enduring Understanding (STB-1): Humans can mitigate their impact on land and water resources through sustainable use.

Learning Objective STB-1.B: Describe methods for mitigating problems related to urban runoff.

• STB-1.B.1 Methods to increase water infiltration include replacing traditional pavement with permeable pavement, planting trees, increased use of public transportation, and building up, not out.

Enduring Understanding (STB-1): Humans can mitigate their impact on land and water resources through sustainable use.

Learning Objective STB-1.C: Describe integrated pest management.

• STB-1.C.1 Integrated pest management (IPM) is a combination of methods used to effectively control pest species while minimizing the disruption to the environment. These methods include biological, physical, and limited chemical methods such as biocontrol, intercropping, crop rotation, and natural predators of the pests.

Learning Objective STB-1.D: Describe the benefits and drawbacks of integrated pest management (IPM).

• STB-1.D.1 The use of integrated pest management (IPM) reduces the risk that pesticides pose to wildlife, water supplies, and human health.
• STB-1.D.2 Integrated pest management (IPM) minimizes disruptions to the environment and threats to human health but can be complex and expensive.

Enduring Understanding (STB-1): Humans can mitigate their impact on land and water resources through sustainable use.

Learning Objective STB-1.E: Describe sustainable agricultural and food production practices.

• STB-1.E.1 The goal of soil conservation is to prevent soil erosion. Different methods of soil conservation include contour plowing, windbreaks, perennial crops, terracing, no-till agriculture, and strip cropping.
• STB-1.E.2 Strategies to improve soil fertility include crop rotation and the addition of green manure and limestone.
• STB-1.E.3 Rotational grazing is the regular rotation of livestock between different pastures in order to avoid overgrazing in a particular area.

Enduring Understanding (STB-1): Humans can mitigate their impact on land and water resources through sustainable use.

Learning Objective STB-1.F: Describe the benefits and drawbacks of aquaculture.

• STB-1.F.1 Aquaculture has expanded because it is highly efficient, requires only small areas of water, and requires little fuel.
• STB-1.F.2 Aquaculture can contaminate wastewater, and fish that escape may compete or breed with wild fish. The density of fish in aquaculture can lead to increases in disease incidences, which can be transmitted to wild fish.

Enduring Understanding (STB-1): Humans can mitigate their impact on land and water resources through sustainable use.

Learning Objective STB-1.G: Describe methods for mitigating human impact on forests.

• STB-1.G.1 Some of the methods for mitigating deforestation include reforestation, using and buying wood harvested by ecologically sustainable forestry techniques, and reusing wood.
• STB-1.G.2 Methods to protect forests from pathogens and insects include integrated pest management (IPM) and the removal of affected trees.
• STB-1.G.3 Prescribed burn is a method by which forests are set on fire under controlled conditions in order to reduce the occurrence of natural fires.

Enduring Understanding (ENG-3): Humans use energy from a variety of sources, resulting in positive and negative consequences.

Learning Objective ENG-3.A: Identify differences between nonrenewable and renewable energy sources.

• ENG-3.A.1 Nonrenewable energy sources are those that exist in a fixed amount and involve energy transformation that cannot be easily replaced.
• ENG-3.A.2 Renewable energy sources are those that can be replenished naturally, at or near the rate of consumption, and reused.

Enduring Understanding (ENG-3): Humans use energy from a variety of sources, resulting in positive and negative consequences.

Learning Objective ENG-3.B: Describe trends in energy consumption.

• ENG-3.B.1 The use of energy resources is not evenly distributed between developed and developing countries.
• ENG-3.B.2 The most widely used sources of energy globally are fossil fuels.
• ENG-3.B.3 As developing countries become more developed, their reliance on fossil fuels for energy increases.
• ENG-3.B.4 As the world becomes more industrialized, the demand for energy increases.
• ENG-3.B.5 Availability, price, and governmental regulations influence which energy sources people use and how they use them.

Enduring Understanding (ENG-3): Humans use energy from a variety of sources, resulting in positive and negative consequences.

Learning Objective ENG-3.C: Identify types of fuels and their uses.

• ENG-3.C.1 Wood is commonly used as fuel in the forms of firewood and charcoal. It is often used in developing countries because it is easily accessible.
• ENG-3.C.2 Peat is partially decomposed organic material that can be burned for fuel.
• ENG-3.C.3 Three types of coal used for fuel are lignite, bituminous, and anthracite. Heat, pressure, and depth of burial contribute to the development of various coal types and their qualities.
• ENG-3.C.4 Natural gas, the cleanest of the fossil fuels, is mostly methane.
• ENG-3.C.5 Crude oil can be recovered from tar sands, which are a combination of clay, sand, water, and bitumen.
• ENG-3.C.6 Fossil fuels can be made into specific fuel types for specialized uses (e.g., in motor vehicles).
• ENG-3.C.7 Cogeneration occurs when a fuel source is used to generate both useful heat and electricity.

Enduring Understanding (ENG-3): Humans use energy from a variety of sources, resulting in positive and negative consequences.

Learning Objective ENG-3.D: Identify where natural energy resources occur.

• ENG-3.D.1 The global distribution of natural energy resources, such as ores, coal, crude oil, and gas, is not uniform and depends on regions' geologic history.

Enduring Understanding (ENG-3): Humans use energy from a variety of sources, resulting in positive and negative consequences.

Learning Objective ENG-3.E: Describe the use and methods of fossil fuels in power generation.

• ENG-3.E.1 The combustion of fossil fuels is a chemical reaction between the fuel and oxygen that yields carbon dioxide and water and releases energy.
• ENG-3.E.2 Energy from fossil fuels is produced by burning those fuels to generate heat, which then turns water into steam. That steam turns a turbine, which spins a generator, producing electricity.
• ENG-3.E.3 Humans use a variety of methods to extract fossil fuels from the earth for energy generation.

Learning Objective ENG-3.F: Describe the effects of fossil fuels on the environment.

• ENG-3.F.1 Hydrologic fracturing (fracking) can cause groundwater contamination and the release of volatile organic compounds.

Enduring Understanding (ENG-3): Humans use energy from a variety of sources, resulting in positive and negative consequences.

Learning Objective ENG-3.G: Describe the use of nuclear energy in power generation.

• ENG-3.G.1 Nuclear power is generated through fission, where atoms of Uranium-235, which are stored in fuel rods, are split into smaller parts after being struck by a neutron. Nuclear fission releases a large amount of heat, which is used to generate steam, which powers a turbine and generates electricity.
• ENG-3.G.2 Radioactivity occurs when the nucleus of a radioactive isotope loses energy by emitting radiation.
• ENG-3.G.3 Uranium-235 remains radioactive for a long time, which leads to the problems associated with the disposal of nuclear waste.
• ENG-3.G.4 Nuclear power generation is a nonrenewable energy source. Nuclear power is considered a cleaner energy source because it does not produce air pollutants, but it does release thermal pollution and hazardous solid waste.

Learning Objective ENG-3.H: Describe the effects of the use of nuclear energy on the environment.

• ENG-3.H.1 Three Mile Island, Chernobyl, and Fukushima are three cases where accidents or natural disasters led to the release of radiation. These releases have had short- and long-term impacts on the environment.
• ENG-3.H.2 A radioactive element's half-life can be used to calculate a variety of things, including the rate of decay and the radioactivity level at specific points in time.

Enduring Understanding (ENG-3): Humans use energy from a variety of sources, resulting in positive and negative consequences.

Learning Objective ENG-3.I: Describe the effects of the use of biomass in power generation on the environment.

• ENG-3.I.1 Burning of biomass produces heat for energy at a relatively low cost, but it also produces carbon dioxide, carbon monoxide, nitrogen oxides, particulates, and volatile organic compounds. The overharvesting of trees for fuel also causes deforestation.
• ENG-3.I.2 Ethanol can be used as a substitute for gasoline. Burning ethanol does not introduce additional carbon into the atmosphere via combustion, but the energy return on energy investment for ethanol is low.

Enduring Understanding (ENG-3): Humans use energy from a variety of sources, resulting in positive and negative consequences.

Learning Objective ENG-3.J: Describe the use of solar energy in power generation.

• ENG-3.J.1 Photovoltaic solar cells capture light energy from the sun and transform it directly into electrical energy. Their use is limited by the availability of sunlight.
• ENG-3.J.2 Active solar energy systems use solar energy to heat a liquid through mechanical and electric equipment to collect and store the energy captured from the sun.
• ENG-3.J.3 Passive solar energy systems absorb heat directly from the sun without the use of mechanical and electric equipment, and energy cannot be collected or stored.

Learning Objective ENG-3.K: Describe the effects of the use of solar energy in power generation on the environment.

• ENG-3.K.1 Solar energy systems have low environmental impact and produce clean energy, but they can be expensive. Large solar energy farms may negatively impact desert ecosystems.

Enduring Understanding (ENG-3): Humans use energy from a variety of sources, resulting in positive and negative consequences.

Learning Objective ENG-3.L: Describe the use of hydroelectricity in power generation.

• ENG-3.L.1 Hydroelectric power can be generated in several ways. Dams built across rivers collect water in reservoirs. The moving water can be used to spin a turbine. Turbines can also be placed in small rivers, where the flowing water spins the turbine.
• ENG-3.L.2 Tidal energy uses the energy produced by tidal flows to turn a turbine.

Learning Objective ENG-3.M: Describe the effects of the use of hydroelectricity in power generation on the environment.

• ENG-3.M.1 Hydroelectric power does not generate air pollution or waste, but construction of the power plants can be expensive, and there may be a loss of or change in habitats following the construction of dams.

Enduring Understanding (ENG-3): Humans use energy from a variety of sources, resulting in positive and negative consequences.

Learning Objective ENG-3.N: Describe the use of geothermal energy in power generation.

• ENG-3.N.1 Geothermal energy is obtained by using the heat stored in the Earth's interior to heat up water, which is brought back to the surface as steam. The steam is used to drive an electric generator.

Learning Objective ENG-3.O: Describe the effects of the use of geothermal energy in power generation on the environment.

• ENG-3.O.1 The cost of accessing geothermal energy can be prohibitively expensive, as is not easily accessible in many parts of the world. In addition, it can cause the release of hydrogen sulfide.

Enduring Understanding (ENG-3): Humans use energy from a variety of sources, resulting in positive and negative consequences.

Learning Objective ENG-3.P: Describe the use of hydrogen fuel cells in power generation.

• ENG-3.P.1 Hydrogen fuel cells are an alternate to non-renewable fuel sources. They use hydrogen as fuel, combining the hydrogen and oxygen in the air to form water and release energy (electricity) in the process. Water is the product (emission) of a fuel cell.

Learning Objective ENG-3.Q: Describe the effects of the use of hydrogen fuel cells in power generation on the environment.

• ENG-3.Q.1 Hydrogen fuel cells have low environmental impact and produce no carbon dioxide when the hydrogen is produced from water. However, the technology is expensive and energy is still needed to create the hydrogen gas used in the fuel cell.

Enduring Understanding (ENG-3): Humans use energy from a variety of sources, resulting in positive and negative consequences.

Learning Objective ENG-3.R: Describe the use of wind energy in power generation.

• ENG-3.R.1 Wind turbines use the kinetic energy of moving air to spin a turbine, which spins a generator, producing electricity.

Learning Objective ENG-3.S: Describe the effects of the use of wind energy in power generation on the environment.

• ENG-3.S.1 Wind energy is a renewable, clean source of energy. However, birds and bats may be killed if they fly into the spinning turbine blades.

Enduring Understanding (ENG-3): Humans use energy from a variety of sources, resulting in positive and negative consequences.

Learning Objective ENG-3.T: Describe methods for conserving energy.

• ENG-3.T.1 Some of the methods for conserving energy around a home include adjusting the thermostat to reduce the use of heat and air conditioning, conserving water, use of energy-efficient appliances, and conservation landscaping.
• ENG-3.T.2 Methods for conserving energy on a large scale include improving fuel economy for vehicles, using BEVs (battery electric vehicles) and hybrid vehicles, using public transportation, and implementing green building design features.

Enduring Understanding (STB-2): Human activities have physical, chemical, and biological consequences for the atmosphere.

Learning Objective STB-2.A: Identify the sources and effects of air pollutants.

• STB-2.A.1 Coal combustion releases air pollutants including carbon dioxide, sulfur dioxide, toxic metals, and particulates.
• STB-2.A.2 The combustion of fossil fuels releases nitrogen oxides into the atmosphere. They lead to the production of ozone, formation of photochemical smog, and convert to nitric acid in the atmosphere, causing acid rain. Other pollutants produced by fossil fuel combustion include carbon monoxide, hydrocarbons, and particulate matter.
• STB-2.A.3 Air quality can be affected through the release of sulfur dioxide during the burning of fossil fuels, mainly diesel fuels.
• STB-2.A.4 Through the Clean Air Act, the Environmental Protection Agency (EPA) regulated the use of lead, particularly in fuels, which dramatically decreased the amount of lead in the atmosphere.
• STB-2.A.5 Air pollutants can be primary or secondary pollutants.

Enduring Understanding (STB-2): Human activities have physical, chemical, and biological consequences for the atmosphere.

Learning Objective STB-2.B: Explain the causes and effects of photochemical smog and methods to reduce it.

• STB-2.B.1 Photochemical smog is formed when nitrogen oxides and volatile organic hydrocarbons react with heat and sunlight to produce a variety of pollutants.
• STB-2.B.2 Many environmental factors affect the formation of photochemical smog.
• STB-2.B.3 Nitrogen oxide is produced early in the day. Ozone concentrations peak in the afternoon and are higher in the summer because ozone is produced by chemical reactions between oxygen and sunlight.
• STB-2.B.4 Volatile Organic Compounds (VOCs), such as formaldehyde and gasoline, evaporate or sublimate at room temperature. Trees are a natural source of VOCs.
• STB-2.B.5 Photochemical smog often forms in urban areas because of the large number of motor vehicles there.
• STB-2.B.6 Photochemical smog can be reduced through the reduction of nitrogen oxide and VOCs.
• STB-2.B.7 Photochemical smog can harm human health in several ways, including causing respiratory problems and eye irritation.

Enduring Understanding (STB-2): Human activities have physical, chemical, and biological consequences for the atmosphere.

Learning Objective STB-2.C: Describe thermal inversion and its relationship with pollution.

• STB-2.C.1 During a thermal inversion, the normal temperature gradient in the atmosphere is altered as the air temperature at the Earth's surface is cooler than the air at higher altitudes.
• STB-2.C.2 Thermal inversion traps pollution close to the ground, especially smog and particulates.

Enduring Understanding (STB-2): Human activities have physical, chemical, and biological consequences for the atmosphere.

Learning Objective STB-2.D: Describe natural sources of $CO_2$ and particulates.

• STB-2.D.1 $CO_2$ appears naturally in the atmosphere from sources such as respiration, decomposition, and volcanic eruptions.
• STB-2.D.2 There are a variety of natural sources of particulate matter.

Enduring Understanding (STB-2): Human activities have physical, chemical, and biological consequences for the atmosphere.

Learning Objective STB-2.E: Identify indoor air pollutants.

• STB-2.E.1 Carbon monoxide is an indoor air pollutant that is classified as an asphyxiant.
• STB-2.E.2 Indoor air pollutants that are classified as particulates include asbestos, dust, and smoke.
• STB-2.E.3 Indoor air pollutants can come from natural sources, human-made sources, and combustion.
• STB-2.E.4 Common natural source indoor air pollutants include radon, mold, and dust.
• STB-2.E.5 Common human-made indoor air pollutants include insulation, Volatile Organic Compounds (VOCs) from furniture, paneling and carpets; formaldehyde from building materials, furniture, upholstery, and carpeting; and lead from paints.
• STB-2.E.6 Common combustion air pollutants include carbon monoxide, nitrogen oxides, sulfur dioxide, particulates, and tobacco smoke.
• STB-2.E.7 Radon-222 is a naturally occurring radioactive gas that is produced by the decay of uranium found in some rocks and soils.

Learning Objective STB-2.F: Describe the effects of indoor air pollutants.

• STB-2.F.1 Radon gas can infiltrate homes as it moves up through the soil and enters homes via the basement or cracks in the walls or foundation. It is also dissolved in groundwater that enters homes through a well.
• STB-2.F.2 Exposure to radon gas can lead to radon-induced lung cancer, which is the second leading cause of lung cancer in America.

Enduring Understanding (STB-2): Human activities have physical, chemical, and biological consequences for the atmosphere.

Learning Objective STB-2.G: Explain how air pollutants can be reduced at the source.

• STB-2.G.1 Methods to reduce air pollutants include regulatory practices, conservation practices, and alternative fuels.
• STB-2.G.2 A vapor recovery nozzle is an air pollution control device on a gasoline pump that prevents fumes from escaping into the atmosphere when fueling a motor vehicle.
• STB-2.G.3 A catalytic converter is an air pollution control device for internal combustion engines that converts pollutants (CO, $NO_x$, and hydrocarbons) in exhaust into less harmful molecules ($CO_2$, $N_2$, $O_2$, and $H_2O$).
• STB-2.G.4 Wet and dry scrubbers are air pollution control devices that remove particulates and/or gases from industrial exhaust streams.
• STB-2.G.5 Methods to reduce air pollution from coal-burning power plants include scrubbers and electrostatic precipitators.

Enduring Understanding (STB-2): Human activities have physical, chemical, and biological consequences for the atmosphere.

Learning Objective STB-2.H: Describe acid deposition.

• STB-2.H.1 Acid rain and deposition is due to nitrogen oxides and sulfur oxides from anthropogenic and natural sources in the atmosphere.
• STB-2.H.2 Nitric oxides that cause acid deposition come from motor vehicles and coal-burning power plants. Sulfur dioxides that cause acid deposition come from coal-burning power plants.

Learning Objective STB-2.I: Describe the effects of acid deposition on the environment.

• STB-2.I.1 Acid deposition mainly affects communities that are downwind from coal-burning power plants.
• STB-2.I.2 Acid rain and deposition can lead to the acidification of soils and bodies of water and corrosion of human-made structures.
• STB-2.I.3 Regional differences in soils and bedrock affect the impact that acid deposition has on the region—such as limestone bedrock's ability to neutralize the effect of acid rain on lakes and ponds.

Enduring Understanding (STB-2): Human activities have physical, chemical, and biological consequences for the atmosphere.

Learning Objective STB-2.J: Describe human activities that result in noise pollution and its effects.

• STB-2.J.1 Noise pollution is sound at levels high enough to cause physiological stress and hearing loss.
• STB-2.J.2 Sources of noise pollution in urban areas include transportation, construction, and domestic and industrial activity.
• STB-2.J.3 Some effects of noise pollution on animals in ecological systems include stress, the masking of sounds used to communicate or hunt, damaged hearing, and causing changes to migratory routes.

Enduring Understanding (STB-3): Human activities, including the use of resources, have physical, chemical, and biological consequences for ecosystems.

Learning Objective STB-3.A: Identify differences between point and nonpoint sources of pollution.

• STB-3.A.1 A point source refers to a single, identifiable source of a pollutant, such as a smokestack or waste discharge pipe.
• STB-3.A.2 Nonpoint sources of pollution are diffused and can therefore be difficult to identify, such as pesticide spraying or urban runoff.

Enduring Understanding (STB-3): Human activities, including the use of resources, have physical, chemical, and biological consequences for ecosystems.

Learning Objective STB-3.B: Describe the impacts of human activities on aquatic ecosystems.

• STB-3.B.1 Organisms have a range of tolerance for various pollutants. Organisms have an optimum range for each factor where they can maintain homeostasis. Outside of this range, organisms may experience physiological stress, limited growth, reduced reproduction, and in extreme cases, death.
• STB-3.B.2 Coral reefs have been suffering damage due to a variety of factors, including increasing ocean temperature, sediment runoff, and destructive fishing practices.
• STB-3.B.3 Oil spills in marine waters cause organisms to die from the hydrocarbons in oil. Oil that floats on the surface of water can coat the feathers of birds and fur of marine mammals. Some components of oil sink to the ocean floor, killing some bottom-dwelling organisms.
• STB-3.B.4 Oil that washes up on the beach can have economic consequences on the fishing and tourism industries.
• STB-3.B.5 Oceanic dead zones are areas of low oxygen in the world's oceans caused by increased nutrient pollution.
• STB-3.B.6 An oxygen sag curve is a plot of dissolved oxygen levels versus the distance from a source of pollution, usually excess nutrients and biological refuse.
• STB-3.B.7 Heavy metals used for industry, especially mining and burning of fossil fuels, can reach the groundwater, impacting the drinking water supply.
• STB-3.B.8 Litter that reaches aquatic ecosystems, besides being unsightly, can create intestinal blockage and choking hazards for wildlife and introduce toxic substances to the food chain.
• STB-3.B.9 Increased sediment in waterways can reduce light infiltration, which can affect primary producers and visual predators. Sediment can also settle, disrupting habitats.
• STB-3.B.10 When elemental sources of mercury enter aquatic environments, bacteria in the water convert it to highly toxic methylmercury.