AP Environmental Science Unit 6 Exam

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Renewable and nonrenewable energy sources.

Renewable energy: sources include solar, wind, hydroelectric, geothermal, and biomass.

Nonrenewable energy sources

Coal, oil, natural gas, and nuclear.

Most commonly used source of fuel in developing countries.

Biomass, such as wood, charcoal, and animal dung

Country with the largest proven reserve of coal.

United States

Environmental issues associated with sulfur emissions.

Sulfur emissions contribute to acid rain, soil and water acidification, respiratory problems in humans and animals, damage forests, harm aquatic ecosystems, corrode buildings.

Human health issues associated with coal-powered plants.

Coal power plants release pollutants like particulate matter, mercury, and sulfur dioxide, which can cause respiratory diseases (asthma, bronchitis), cardiovascular issues, and neurological damage from mercury exposure.

Two ways fossil fuel-burning power plants can reduce sulfur emissions.

Power plants can install scrubbers in smokestacks to remove sulfur dioxide before it reaches the atmosphere. They can also switch to low-sulfur coal or use alternative energy sources.

Two environmental benefits of using natural gas over coal.

Natural gas produces fewer CO₂ emissions per unit of energy, reducing its contribution to climate change. It also releases fewer particulates and sulfur dioxide, leading to improved air quality.

Region of the world that has been the largest exporter of oil.

The Middle East (Saudi Arabia)

Activities associated with drilling oil in ANWR and their potential consequences.

1) Seismic testing can disrupt wildlife behavior and migration.
2) Infrastructure development (roads, pipelines) can fragment habitats and increase the risk of oil spills.

Characteristics that make Arctic tundra particularly fragile.

1) Slow growth and recovery - Arctic ecosystems take a long time to recover from disturbances due to short growing seasons.
2) Permafrost dependency - Damage to permafrost from drilling or warming can release methane and CO₂, accelerating climate change.

Production of oil from tar sands.

Tar sands are mined and processed to extract bitumen. The bitumen is then heated or chemically treated to separate the oil, which is further refined into usable fuel.

Negative environmental consequences of oil production from tar sands.

1) Deforestation and habitat destruction - Large areas of land are cleared for tar sand mining.
2) Water pollution - Toxic waste from extraction contaminates local water sources.

Example of electrical cogeneration.

A factory that uses excess heat from electricity generation to provide heating for industrial processes or nearby buildings.

Natural oil contamination in the ocean.

Natural oil seeps, such as those off the coast of California, release oil into the ocean without human activity.

Pro and con of chemical dispersants used on oil spills.

Pro: Helps break down oil into smaller droplets, making it easier for microbes to degrade.
Con: Can be toxic to marine life and make oil sink to the ocean floor, harming ecosystems.

Common way to physically or mechanically clean up oil spills.

Booms and skimmers are used to contain and remove oil from the surface of the water before it spreads.

Economic and environmental problems from oil spills on coastal towns.

Economic: Loss of tourism and fishing industry revenue.

Environmental: Long-term damage to marine ecosystems and wildlife deaths from oil exposure.

Type of environment that would most likely yield oil in the future.

Sedimentary basins with organic-rich rock, such as deep-sea environments or Arctic regions.

Two end uses of oil and a conservation measure for each.

1) Transportation (gasoline, diesel) - Use fuel-efficient vehicles or public transport.

2) Plastics production - Recycle and reduce plastic use.

Why oil production doubled in the 1960s.

Technological advancements, increased global demand, new oil discoveries, OPEC's formation, and improved infrastructure led to the rise in production.

COMPARE the environmental benefits of running combustion engines on natural gas vs gas

Natural gas can offer life cycle greenhouse gas (GHG) emissions benefits over conventional fuels

Process of fracking and how it gets natural gas

A process where a mixture of water, sand, and chemicals is pumped at high pressure into a deep underground well to create cracks in rock formations, allowing trapped natural gas to flow out and be extracted to the surface

Negative environmental consequence of fracking

Creates vast amounts of wastewater, emits greenhouse gases such as methane, releases toxic air pollutants and generates noise.

Parts and functions of a nuclear power plant.

• Reactor core - Contains fuel rods where fission occurs.

• Control rods - Regulate the fission reaction.

• Coolant - Transfers heat away from the core.

• Turbine - Spins to generate electricity.

• Cooling tower - Releases excess heat.

Pros and cons of nuclear-generated energy.

Pros: Low greenhouse gas emissions, high energy output.

Cons: Radioactive waste, risk of meltdowns.

How nuclear power plants may cause thermal pollution.

Excess heat from cooling water is released into nearby rivers or lakes, disrupting aquatic ecosystems by lowering oxygen levels.

Human activity that produces high-level and low-level radioactive waste.

High-level waste - Used nuclear fuel from reactors.

Low-level waste - Medical equipment from radiation therapy.

Three characteristics of the proposed nuclear waste site in the Yucca Mountains.

1) Remote location to minimize human exposure.

2) Geological stability to prevent leaks.

3) Low water flow to reduce groundwater contamination.

Two other ways to dispose of high-level nuclear waste and their feasibility:

1. Deep Borehole Disposal: Drilling boreholes 3-5 km deep into stable geological formations and sealing waste inside. Feasibility: Technologically possible but expensive; political and geological challenges exist.

2. Sub-Seabed Disposal: Burying waste beneath the ocean floor in geologically stable regions. Feasibility: Technically feasible, but international treaties prohibit ocean dumping.

United States plan for long-term disposal of high-level nuclear waste:

The U.S. planned to store high-level nuclear waste at Yucca Mountain, Nevada, a deep geological repository. However, political and environmental concerns stalled the project. Currently, waste is stored on-site at reactors and in interim storage facilities while new permanent solutions are debated.

One of the three nuclear power plant accidents and the consequences:

Fukushima Daiichi (2011): A 9.0-magnitude earthquake and tsunami caused reactor meltdowns, hydrogen explosions, and radiation leaks. Consequences: Mass evacuations, contaminated land and water, economic losses, and long-term health monitoring for radiation exposure.

Sublethal health effect of radiation and how radiation causes this health effect:

Cataracts: Ionizing radiation damages lens proteins and DNA in eye cells, leading to clouding of the lens and impaired vision over time.

COMPARE high-level and low-level radioactive waste with a specific isotope for each:

• High-Level Waste: Comes from spent nuclear fuel and is highly radioactive. Example: Cesium-137 (Cs-137) (half-life ~30 years), a fission product emitting beta and gamma radiation.

• Low-Level Waste: Includes contaminated gloves, tools, and medical waste, with lower radiation levels. Example: Tritium (H-3) (half-life ~12 years), emitting low-energy beta radiation.

Concept of radioactive half-life:

Radioactive half-life is the time required for half of a radioactive substance to decay into a more stable form. It determines how long a material remains hazardous.

DEDUCE the half-life of an element from its graphically represented decay rates:

By analyzing a decay curve, identify the time at which the remaining quantity is half its original value. Repeat for additional half-lives to confirm consistency.

COMPARE fission and fusion:

• Fission: Splitting heavy nuclei (e.g., uranium-235) into smaller fragments, releasing energy. Used in nuclear reactors.

• Fusion: Combining light nuclei (e.g., hydrogen isotopes) to form heavier nuclei, releasing more energy than fission. Requires extreme temperatures.

Why creating biodiesels from algae is considered carbon neutral.

Algae absorb CO₂ during growth, offsetting emissions when the biofuel is burned.

Two economic or societal problems of producing fuel from corn.

1) Increased food prices - Diverts corn from food to fuel production.

2) High water and land use - Requires large agricultural areas and irrigation.

How PV (photovoltaic) cells produce electricity.

Sunlight excites electrons in a semiconductor, generating an electric current.

Example of passive solar energy design.

A home with south-facing windows to maximize sunlight absorption in winter.

Limitations of photovoltaic cells' ability to produce electricity.

PV cells depend on sunlight availability and have lower efficiency compared to other energy sources.

Environmental cost of PV cell production.

Mining for silicon and rare metals causes habitat destruction and pollution.

Suggest two governmental policies that would increase the use of PV cells.

1) Tax credits and rebates for homeowners and businesses that install photovoltaic (PV) solar panels.

2) Net metering policies that allow solar panel owners to sell excess electricity back to the grid, making solar power more financially attractive.

Pros and cons of hydroelectric power (dams).

Pros: Renewable, low greenhouse gas emissions, provides flood control.

Cons: Disrupts aquatic ecosystems, displaces communities, sediment buildup reduces efficiency.

Two economic benefits of dams aside from cheaper electricity.

1) Provides irrigation for agriculture.

2) Creates recreational opportunities such as boating and fishing.

How dams affect floodplains in a negative way.

Dams alter natural water flow, reducing sediment deposition downstream and disrupting ecosystems that rely on seasonal flooding.

Largest hydroelectric dam.

The Three Gorges Dam in China.

How the ocean can be used to generate electricity.

Tidal energy uses underwater turbines placed in areas with strong tidal currents to generate electricity, while wave energy captures the motion of waves to drive generators.

Outline the geothermal production of electricity.

Hot water or steam from underground reservoirs is used to spin a turbine connected to a generator, producing electricity.

Geothermal hot spot

Iceland, which generates most of its electricity from geothermal energy.

Two environmental benefits of switching from coal to wind-generated electricity.

1) Reduces greenhouse gas emissions.

2) Lowers air pollution, improving public health.

Economic and environmental benefit of offshore wind projects.

Economic: Creates jobs in renewable energy industries.

Environmental: Does not require land, reducing habitat destruction.

How hydrogen fuel vehicles work.

Hydrogen gas is fed into a fuel cell, where it reacts with oxygen to produce electricity, powering an electric motor. The only byproduct is water vapor.

Two energy conservation measures that can be applied in our homes.

1) Use energy-efficient appliances.

2) Install LED lighting to reduce electricity use.

Two water conservation measures that can be applied in our homes.

1) Use low-flow toilets and showerheads.

2) Fix leaks to prevent water waste.

Fuel efficiency standards.

Government regulations that set minimum miles per gallon (MPG) requirements for vehicles to reduce fuel consumption and emissions.

Two environmental benefits of electric vehicles over gas-powered vehicles.

1) Lower CO₂ emissions.

2) Reduces air pollutants like nitrogen oxides and particulates.

Two governmental policies that would increase electric vehicle usage.

1) Tax credits and subsidies for EV buyers.

2) Investment in charging station infrastructure.

Ecological footprint

Measure of human demand on Earth's ecosystems, including land, water, and resources needed to sustain a person's lifestyle.

Subsidizing

When the government provides financial support to businesses or industries to lower costs and encourage production.

Tax incentives

Reductions in taxes to encourage certain behaviors, such as buying energy-efficient appliances or electric vehicles.

Identification

Recognizing and classifying environmental issues, species, or pollutants.

Denitrification

The process by which bacteria convert nitrates into nitrogen gas, returning it to the atmosphere.

Eutrophication

The excessive nutrient buildup in water bodies, leading to algal blooms, oxygen depletion, and aquatic ecosystem collapse.

Desertification

The process by which fertile land becomes desert due to drought, deforestation, or unsustainable agriculture.

Two ecological and economic services provided by forests.

Ecological: Absorb CO₂ and provide habitat for biodiversity.

Economic: Timber for construction and jobs in forestry.

Point source and non-point source pollution.

Point source pollution comes from a single, identifiable location (e.g., factory discharge).

Non-point source pollution comes from diffuse sources (e.g., agricultural runoff).

Calculate percent change (no equation given).

Percent change = [(New Value - Old Value) / Old Value] × 100%

Deduce an explanation given a data table.

Look for trends, relationships, or anomalies in the data and explain possible causes or implications.

Analyze a line graph

Identify trends over time, peaks, declines, and any correlation between variables.

Analyze a bar graph

Compare different categories by evaluating bar height and distribution.