ENSC 001 MIDTERM 1 — COMPLETE QUIZLET (Lectures 1–5)

What are the three main learning goals of Environmental Science (ENSC 001)?

(1) Explain how Earth systems work and how humans disrupt them. (2) Identify key human sectors that impact the environment. (3) Apply sustainability and environmental justice principles to solutions.

What is consumption?

The use of materials and energy to meet human needs such as food, water, energy, and shelter. Overconsumption drives most environmental problems.

What are renewable resources?

Natural resources that can replenish on human time scales — e.g., sunlight, wind, forests (if managed sustainably).

What are nonrenewable resources?

Resources that exist in finite supply — e.g., fossil fuels, metals, and minerals.

What is the Ecological Footprint?

The amount of land and water needed to supply a population's resources and absorb its waste. Humanity uses about 1.7 Earths' worth of resources today.

What is the IPAT Model?

Environmental Impact = Population × Affluence × Technology (I = P × A × T).

What does each part of IPAT represent?

P = population size, A = consumption per person, T = impact per unit of consumption.

Can technology reduce impact in IPAT?

Yes. Green technologies can reduce total impact even as population or wealth grow.

What are the limitations of the IPAT model?

It oversimplifies complex systems and excludes political, social, and cultural factors.

What is sustainability?

Using resources at a rate that allows future generations to meet their needs without degrading ecosystems.

What are the three pillars of sustainability?

Environment (planet), Economy (profit), and Society (people).

What is the Tragedy of the Commons?

Shared resources get overused because individuals act in self-interest — e.g., overfishing, overgrazing, pollution of air or water.

What is a positive feedback loop?

A process that amplifies change (e.g., global warming → ice melts → less reflection → more warming).

What is a negative feedback loop?

A process that stabilizes change (e.g., predator-prey balance, body temperature regulation).

What was the Frontier Attitude?

The early American belief that natural resources were unlimited and meant for exploitation and expansion.

Who was Gifford Pinchot?

First head of the U.S. Forest Service; promoted utilitarian conservation — using natural resources wisely for "the greatest good for the greatest number."

Who was John Muir?

Founder of the Sierra Club; promoted biocentric preservation, protecting nature for its own intrinsic value.

Who was Aldo Leopold and what is the Land Ethic?

Leopold taught that humans are part of an ecological community; we have an ethical duty to care for the land and all its members.

What is the difference between shallow and deep ecology?

Shallow = human-centered conservation; Deep = all life has intrinsic value, independent of human use.

What was the General Revision Act (1891)?

Allowed presidents to establish forest reserves to prevent overuse of public land.

What was the Antiquities Act (1906)?

Gave presidents the power to protect landmarks and natural areas as national monuments.

What was the Hetch Hetchy controversy?

Debate over damming a Yosemite valley for San Francisco's water. Muir opposed (preservation), Roosevelt supported (utilitarian use).

What was the Dust Bowl?

1930s event where poor farming and drought caused massive soil erosion and agricultural collapse.

What is NEPA (1970)?

The National Environmental Policy Act; requires Environmental Impact Statements for federal projects.

What agency was created in 1970?

The Environmental Protection Agency (EPA) — enforces environmental laws and regulations.

What are major 1970s environmental laws?

Clean Air Act (1970), Clean Water Act (1972), Endangered Species Act (1973), Safe Drinking Water Act (1974), and CERCLA/Superfund (1980).

What is the Endangered Species Act (1973)?

Protects species at risk of extinction and preserves their habitats.

What is the Safe Drinking Water Act (1974)?

Ensures public water systems meet health-based safety standards.

What is environmental justice?

The fair treatment of all people regardless of race or income in environmental policy.

What is an externality?

A cost or benefit of an action not reflected in its market price (e.g., pollution causing health costs).

What is cost-benefit analysis?

Weighing the costs of environmental protection against its predicted benefits.

What is the Pollution Optimum?

The economic balance point where pollution control cost equals pollution damage cost.

What are ecosystem services?

Natural benefits ecosystems provide — e.g., pollination, soil fertility, water purification, flood control, climate regulation.

What is GDP vs GPI?

GDP measures total economic output; GPI adjusts for environmental and social costs to measure true progress.

What is ecology?

The study of relationships between organisms and their environment.

What are the key components of an ecosystem?

Biotic (living) and abiotic (nonliving) factors that interact through energy flow and nutrient cycling.

What is the First Law of Thermodynamics?

Energy cannot be created or destroyed, only transformed.

What is the Second Law of Thermodynamics?

Energy transformations increase disorder (entropy); usable energy is lost as heat.

What is photosynthesis?

Process where plants convert CO₂ and water into glucose and oxygen using sunlight.

What is cellular respiration?

The process organisms use to release energy by breaking down glucose with oxygen.

What is gross primary productivity (GPP)?

Total solar energy captured by plants during photosynthesis.

What is net primary productivity (NPP)?

GPP minus energy used for respiration — energy available to consumers.

Which ecosystems have high NPP?

Tropical rainforests, coral reefs, and wetlands.

What are the levels of a food web?

Producers → Primary consumers → Secondary consumers → Tertiary consumers → Decomposers.

How does energy flow through ecosystems?

In one direction — from sunlight to producers to consumers to decomposers; about 10% energy transfer per level.

What is natural selection?

The process where individuals with advantageous traits survive and reproduce, leading to evolutionary change.

What is adaptation?

A heritable trait that increases survival or reproduction in a particular environment.

What are the types of survivorship curves?

Type I: low early mortality (humans), Type II: constant mortality (birds), Type III: high early mortality (fish/insects).

What is the population growth rate formula?

r = (births - deaths) + (immigration - emigration).

What is exponential vs logistic growth?

Exponential = rapid increase without limits; Logistic = slows as it nears carrying capacity.

What are density-dependent factors?

Factors that increase with population size (disease, competition, food limits).

What are density-independent factors?

Factors unaffected by population size (weather, fires, droughts).

What is carrying capacity?

The maximum population size that an environment can sustain indefinitely.

What are species interactions?

Mutualism (+/+), Commensalism (+/0), Parasitism (+/-), Competition (-/-), Predation (+/-).

What is a niche?

The role and resource use of a species in its environment.

What is the competitive exclusion principle?

No two species can occupy the same niche indefinitely; one will outcompete the other.

What is a keystone species?

A species with a disproportionately large effect on ecosystem stability (e.g., sea otters, wolves).

What are biogeochemical cycles?

Natural processes that recycle matter through ecosystems — water, carbon, nitrogen, phosphorus, and sulfur cycles.

What are the steps of the nitrogen cycle?

Nitrogen fixation → Nitrification → Assimilation → Ammonification → Denitrification.

What is the carbon cycle?

Movement of carbon through the atmosphere, organisms, soil, and oceans via photosynthesis and respiration.

What is the phosphorus cycle?

Cycle of phosphorus between rocks, soil, and organisms; no gaseous phase.

What is the sulfur cycle?

Circulation of sulfur through land, air, and water; burning fossil fuels releases sulfur → acid rain.

What is the water cycle?

Movement of water via evaporation, condensation, precipitation, runoff, and infiltration.

What is albedo?

The reflectivity of a surface; ice/snow = high albedo (reflective), dark ocean = low albedo (absorbs heat).

How does Earth's tilt affect climate?

Earth's 23.5° tilt causes seasons by altering sunlight intensity and day length.

What are the layers of the atmosphere?

Troposphere, Stratosphere, Mesosphere, Thermosphere, Exosphere.

What is the composition of the atmosphere?

~78% nitrogen, 21% oxygen, and trace gases like CO₂, methane, and water vapor.

What happens in the troposphere?

It's the lowest layer; contains weather, clouds, and most of Earth's air mass.

What is the stratosphere known for?

Contains the ozone layer that absorbs harmful UV radiation.

What are Hadley, Ferrel, and Polar cells?

Global convection patterns that redistribute heat and moisture, creating climate zones.

What is the Coriolis Effect?

The deflection of moving air/water due to Earth's rotation — right in the Northern Hemisphere, left in the Southern.

What are gyres?

Large circular ocean currents that redistribute heat across the planet.

What is upwelling?

The rise of cold, nutrient-rich water from deep oceans to the surface, boosting productivity.

What is El Niño?

A periodic warming of Pacific waters that disrupts global weather — wetter winters in California, droughts in Asia.

What is La Niña?

A cooling phase of the Pacific — usually brings drier California weather and stronger Atlantic hurricanes.

What are teleconnections?

Global climate linkages where ocean changes (like El Niño) affect weather patterns worldwide.