AP Environmental Science - Review

Unit 1 - The Living World: Ecosystems

Introduction to ecosystems

$Biotic$ (once / currently living) / $Abiotic$ (never lived)

$Organism$ (living being) → $Population$ (a group of the same organisms) → $Community$ (a group of different populations) → $Ecosystem$ (a community and its abiotic factors)

$Biome$ (a unique environment with distinct characteristics) → $Biosphere$ (all of the biomes on Earth)

Terrestrial and aquatic biomes

Terrestrial Biomes are primarily affected by precipitation and temperature

Common $Terrestrial Biomes$

$Tundra$, $Taiga$, $Prairie$, $Shrubland$, $Desert$, $Temperate Deciduous Forest$, $Rainforest$

Common $Aquatic Biomes$

$River / Stream$, $Pond$, $Lake$, $Wetland$ ($Bog$, $Marsh$, $Swamp$), $Coral Reef$, $Ocean$, etc.

$Climatograms$

Help determine type of biome

Primary productivity

$Photosynthesis$ basic formula: CO₂ + H₂O (+ sunlight) → sugar + O₂

$NPP (Net Primary Productivity) = GPP (Gross Primary Productivity) - R (Respiration)$

Net Primary Productivity is the energy available from plants accounting for their respiration

$Eutrophication$ - a process in which runoff from humans pollutes water with excess nutrients, causing an overflow of plants

Carbon, nitrogen, phosphorus, and water cycles

$Carbon Cycle$

$Nitrogen Cycle$

$Phosphorus Cycle$

$Water Cycle$

Trophic levels

Each $trophic level$ of an ecosystem is the next highest layer of consumption

The flow of energy in an ecosystem and the 10% rule

In a food diagram, arrows go from where the energy starts to where it ends

Each level of a food chain consumes about $10$ of the energy of the lower level

Energy begins with $primary producers$ (getting energy from the sun) to $primary consumers$ to $secondary consumers$ and so on, and at each stage $decomposers$ return some energy to producers

$Herbivores$ eat only plants, $omnivores$ eat both plants and animals, and $carnivores$ eat only animals

$Autotrophs$ can produce their own food, heterotrophs require consumption to get energy

$Trophic Cascades$ are events that affect the presence of one organism that highlight the complex relationships of ecosystems

$Bottom-up Ecosystems$ - producers limit the consumer populations

$Top-down Ecosystems$ - consumers control producer populations

Types of Relationships

$Competition$ (limited resources): $intraspecies$ (within one) and $interspecies$ (across multiple)

• $specialists$ - consume a specific type of resource
• $generalists$ - consumer a variety of types of resources

• when species overlap in consumption, one is successful (the original niches of both organisms are the $fundamental niches$, while the after-competition niches of both organisms are the $realized niches$)
• $resource partitioning$ is when organisms consume a specific resource (ex: birds eating different parts of trees)

$Symbiosis$ - living together in harmony

$Mutualism$ (both organisms benefit), $Commensalism$ (one organism benefits and the other is unaffected), $Parasitism$ (one organism benefits and the other is harmed)

$Food chains$ and $food webs$

Unit 2 - The Living World: Biodiversity

Introduction to biodiversity

$Biodiversity$ and $Evolution$ - genetic mutations lead to varying traits within a species, and the spread of these genes help drive evolution based on whether the trait is harmful, uneffective, or beneficial

Types of Biodiversity - $Genetic$ (variation of alleles within a species), $Species$ (variation of species within an ecosystem), $Ecological$ (variation of ecosystems within a region/biosphere)

• $species richness$ is how many species are present and $species evenness$ is the proportion of each species

$Darwin’s Postulates$ (of Evolution)

1. $Traits must be varied in a species$
2. $The focused trait must be heritable$
3. $Selective Pressure - not all organisms survive$
4. $The trait helps reproduction/survival$

$Ecosystem services$

$Regulating$ - benefits to environment from ecosystems

• ex: air quality, runoff/erosion control, natural hazard resistance, pollination

$Supporting$ - helps ecosystem health to provide other benefits

• nutrient cycling, soil formation, photosynthesis

$Provisioning$ - material production

• ex: food, biomass, fuel, medicine, etc.

$Cultural$ - cultural benefits of ecosystems (recreational, health, etc.)

• ex: religious practices, tourism, etc.

$Island Biogeography$

Ecological tolerance

$Ecosystem Resilience$ - how well an ecosystem is able to recover from an ecosystems disruption

$Ecosystem Resistance$ - how well an ecosystem responds to an ecosystems disruption

$Tolerance$ - the ability to live in a variety of environmental conditions

$Keystone Species$ - species required for ecosystem stability

$Indicator Species$ - have a very low tolerance and indicate environmental conditions

$Invasive Species$ - non-native and harmful species

Natural disruptions to ecosystems

$Bottleneck Effect$ - a decrease in the number of alleles in a species, leads to either recovery or extinction

$Ecosystem Disruptions$ - an event or process that harms ecosystem health (usually decreasing biodiversity)

• ex: extreme changes in temperature or precipitation, sea level rise, natural disasters (tornadoes, tsunamis, floods, forest fires, etc.), migration, invasive species, human activity (habitat destruction, pollution, etc.)

Ecological succession

$Primary Succession$ - the development of an ecosystem from scratch (takes thousands of years)

• soil isn’t developed

$Secondary Succession$ - the development of an ecosystem after an ecosystem disruption (takes at least 50 years)

• soil is already developed

Unit 3 - Populations

Generalist and specialist species

Generalists use a variety of resources and are adaptable, while specialist species use specific resources and are susceptible to change

$Survivorship curves$

$Type I$ - few and rare offspring (ex: tortoises)

$Type II$ - in between (ex: birds)

$Type III$ - lots of and frequent offspring (ex: bacteria)

$r-selected species$ - unstable environment, high fecundity, short generations, small size, type III

$K-selected species$ - stable environment, high parental care, fewer offspring, large size, type I

Population growth and resource availability

$Carrying Capacity$ - the maximum number of individuals that can be supported

The most important resources are food and space

$(Births(+) - Deaths(-)) + (Immigration(+) - Emigration(-)) = Natural Increase + Net Migration = Growth Rate$

Population Limiting Factors -

• $Density-dependent$ - competition, disease, parasitism, predation
• $Density-independent$ - pollution, natural disasters

$Doubling time = growth rate / 70$

$Population Distributions$

$Types of Growth$

$Age structure diagrams$

$Human population dynamics$

$Total Fertility Rate = (Children / Women)$

Unit 4 - Earth Systems and Resources

Tectonic plates

Types: $oceanic$ or $continental$, and convergent, divergent, or transform

$Convergent$ - two plates push together, causing one to slide up and one to submerge

• causes volcanoes, islands, mountains, etc.

$Divergent$ - two plates slide away from one another

• causes mountains, volcanoes, rifts
• $Mid-atlantic Ridge$

$Transform$ - two plates slide against one another

• causes earthquakes

Faults, $hotspots$, and islands form at boundaries

$Pacific Ring of Fire$

Soil formation and erosion

$Parent Material$ - original rock substance that gets broken down

$Weathering$ - the process of breaking down rocks (wind, rain, etc.)

• factors: type of parent material, climate, topography, biological factors, time

$Soil Profile$ - the layers of soil

$Soil Erosion$ - movement of soil caused by water, wind, gravity, topography, and human impacts (deforestation, overgrazing, pesticides/fertilizers, tillage, etc.)

$Solutions to Erosion$:

• $Sheet$ - plant cover
• $Rill$ - strip cropping
• $Gully$ - diverting water, contour farming

$Soil Texture$ - mix of sand (largest, most permeable), silt (medium), and clay (smallest, least permeable)

$Soil Tests$: chemical (nitrogen, phosphorus, pH), physical (soil composition, water retention), biological (earthworms, bacteria, etc.)

$Percolation$ - water moving into the ground

$Infiltration$ - chemicals moving into the ground with water

Earth's atmosphere

$Troposphere$ (tropopause) - causes weather

$Stratosphere$ - ozone layer

$Mesosphere$ - asteroids

$Thermosphere$ - Aurora Borealis

$Exosphere$ - outside

Global wind patterns

$Wind cells$ drive currents called $jet streams$

$Trade winds$ are predictable winds that occur at different latitudes

• impacted by the spinning of Earth as well ($Coriolis Effect$)

Earth's geography and climate

$Climate$ is long-term while $weather$ is short-term

Earth’s 23.5 degree tilt is what primarily causes seasons

$Albedo$ - ability to absorb light (white is high, black is low)

$Watershed$

$El Niño and La Niña$

Caused by changes in trade winds

Effects: affects agriculture and climate, and causes upwelling

Unit 5 - Land and Water Use

The $tragedy of the commons$

If a resource goes unused, it will just get used by other organizations.

The $Green Revolution$

Agricultural technologies improved heavily, allowing greater support for a greater population.

• Increased greenhouse gases (25% of total emissions)

$GMOs$ (Genetically-modified Organisms)

• Benefits: more nutritious, less land, better soil quality, resistant to diseases/pests/environmental conditions
• Drawbacks: genes can mutate (can activate sleeper genes), cause more powerful pests/diseases, affects biosphere genetic diversity

$Synthetic Fertilizers$ (help provide nutrients for organisms)

• $Haber-Bosch Process$ helps make nitrogen consumable
• Benefits: cheap, easy to produce/use, animal independent
• Drawbacks: excess runoff, decreased soil quality, uses fossil fuels

Types and effects of irrigation

Irrigation Practice	Description	Benefits / Drawbacks
$Flooding$		==- Ruins typical river flow (harms river ecosystem)- Causes erosion==- Causes salinization- Easy
$Furrowing$		==- Ruins typical river flow (harms river ecosystem)- Causes erosion==- Causes salinization- Easy
$Spraying$		==- Expensive==- Lots of evaporation
$Dripping$		%%- Efficient water use%%==- Expensive==

Pest-control methods

$Integrated Pest Management$ (IPM): controls pests (expensive but sustainable and long-term cheap)

IPM Practice	Description	Benefits / Drawbacks
$Biological$ (gophers, chickens, etc.)		%%- Cheap%%- Effective- Helps maintain ecosystem- Little effort
$Physical$ (scarecrows, prescribed burns)		%%- Cheap%%==- Ineffective==
$Chemical$ (pesticides)		==- Expensive==%%- Effective%%==- Ruins soil and ecosystem==

Meat production methods and overfishing

Meat Practice	Description	Benefits / Drawbacks
General		- High resource cost (land for grazing and growing food)- Pollution through emissions- Excess waste- High demand
$Clear-cutting$
$Overcrowding$		- Breeds and spreads infectious diseases- Cheaper
$Rotating Fields$		- Maintains soil and plants- Requires more land
GMOs

The impacts of mining

Urbanization and ecological footprints

$Urbanization$

Negative Impacts: less $permeability$ and high pollution, less plant cover, overconsumption (and far away from resources), saltwater intrusion for coasts, urban heat island

• Positive Impacts and Solutions: building up not out, less travel distances and more efficient transportation usage, more efficient resource usage (ex: heating/cooling), ecosystems destruction, urban heat island

Introduction to sustainable practices including crop rotation and aquaculture

$Sustainability is when inputs are equal to outputs$

Bad Agricultural Practices: clear-cutting removes forests and therefore biodiversity, $monoculture$ drains the soil of specific nutrients, GMOs can harm biodiversity and can cause pest resistance, $synthetic fertilizers$ affect soil quality, $tilling$ destroys top layers of soil, $slash and burn$ ruins ecosystems, $pesticides$ pollute soil/water and can cause cancer

• Solutions: $crop rotation$ allows for soil restoration, $green manure$ is a natural fertilizer, $GMOs$ can reduce land use, $contour farming$ and $terracing$ helps with runoff, $windbreaks$ prevent erosion, $strip-cropping$ and $cover crops$ and $intercropping$ helps with runoff, $no-till$ agriculture helps allow the soil ecosystems perpetuate, $perennial crops$ help keep soil intact, $spraying$ and $drip irrigation$ efficiently use water and reduce salinization

Bad Aquatic Practices: $commercial fishing technology$ (general), $long-line fishing$, $drift/gill nets$ leads to lots of bycatch, $pursing$ leads to lots of bycatch, $trawling$ destroys seafloors, $sonar$ is efficient but kills fish, $aquaculture$ helps with demand but can lead to excess waste

Unit 6 - Energy Resources and Consumption

Energy sources and fuel types, including fossil fuels, ethanol, and nuclear power

NONRENEWABLE

Fossil fuels (coal, natural gas, oil) are the primary sources of energy today, with nuclear energy behind it

• both nonrenewable energy sources

Coal to Energy conversion: coal is burned, which heats water, which turns into steam, which spins a turbine, which spins a magnet and coils, which uses a generator to convert to electricity

• Cogeneration: when electricity is used but the resulting products have additional benefits (ex: heated water goes to houses after spinning turbines)

Coal Formation: Peat/Humus are condensed using heat and pressure into lignite, which then condenses to bituminous (most common), which finally turns into anthracite (cleanest)

• oil and gas have similar processes, just in marine ecosystems

Natural gas is composed of hydrocarbons

Fracking (hydraulic fracturing) is done by drilling a hole and blowing it up to release gas (causes earthquakes and harmful gases to release)

Fractional Distillation is the separation of crude oil into usable oils based on heating point (highest - liquid petroleum gas, petrol, paraffin, diesel, fuel oil - lowest)

Nuclear Energy is efficient and clean, but has long-lasting nuclear waste, can explode, causes ionizing radiation, and can cause meltdowns (excess heat)

• Nuclear Energy is formed by sending a neutron to a uranium atom which releases energy through fission and creates a chain reaction of more neutron releases

The electric grid uses transformers and checkpoints to alter voltage

Global energy consumption and distribution of natural resources

Mining Types: surface, subsurface, strip, and mountain top

• ore underground is overburden and above ground is spoils
• ore is separated into target material and waste

Uranium (nuclear) - Australia, Kazakhstan, Canada

Crude Oil - Middle East, North Asia, North America

Natural Gas - North America, Asia (primarily Russia)

Coal - everywhere except Western Europe and Africa

Natural sources of energy, including solar power, wind, geothermal, and hydroelectric power

RENEWABLE

Wind Turbines - forms by wind spinning turbines which powers a generator

Solar Panels - forms by

Hydrogen

Energy conservation methods

Unit 7 - Atmospheric Pollution

Introduction to air pollution

Legislation - Clean Air Act of 1956 (London)

Natural Sources of Pollution - pollen, spores, bacteria, dust, soil

There is a positive geometric correlation between temperature and ground level ozone

Clean Air Act of 1970 (U.S.A.)

response to haze in cities

limited the following pollutants: sulfur dioxide (SO2), particulate matter (PM#), lead (Pb), ozone (O3), nitrogen dioxide (NO2), carbon monoxide (CO)

• Particulate Matter - small particles based on micron size (forms from partially combusted “soot”)

VOCs (Volatile Organic Compounds)

composed of C, O, H, Cl & S, come from extraction/transportation of fossil fuels, refining/manufacturing of petrochemicals, consumer use (of products), lack of waste management, etc.

occur naturally, mainly anthropogenically produced

• carcinogens that can affect organ systems

when these react with the sun, they form PANs (Peroxyacyl Nitrates)

Thermal Inversion

When a high pressure layer of hot air forms, cold air is trapped above and below, increasing pollution in the lower layer

Photochemical smog

Smog - smoke + fog; thick gray haze that forms when coal is burned and mixes with moisture

• photochemical (sunlight-caused) and industrial (moisture-caused)
• primarily from fossil fuel combustion (factories or vehicles)

Primary Pollutants (CHONS) →(sunlight)→ Secondary Pollutants

• primary: CO, CO2, SO2, NOx, N2O, NH3, hydrocarbons, VOCs, PM10, PM2.5
• NOx → O3
• NO + VOC → NO2, + UV → NO + O, + O2 → O3
• NO + VOC → O3 + PANs

Indoor air pollution

Methods to reduce air pollutants

Maintain vehicles (last longer), sustainable vehicles, catalytic converters, electrostatic precipitators, scrubbers, etc.

Acid rain

Noise pollution

Unit 8 - Aquatic and Terrestrial Pollution

Sources of pollution

Human impact on ecosystems

Thermal pollution

Solid waste disposal and waste reduction methods

Pollution and human health

Pathogens and infectious diseases

Unit 9 - Global Change

Ozone depletion

Global climate change

Ocean warming and acidification

Invasive species

Human impacts on diversity