Intro to Environmental Science (SPRING26)

What are the steps of the scientific method?

Observation; hypothesis; experiment; data collection; analysis and reporting.

What is a scientific hypothesis?

A testable explanation for an observation.

What is the purpose of a critical experiment?

To test a hypothesis using evidence that can support or reject it.

What was unusual about PCBs in remote Alaskan lakes?

PCBs were present despite no nearby source or direct human contact.

What hypothesis explains PCBs in remote Alaskan lakes?

Air currents transport PCBs from distant pollution sources.

How could atmospheric PCB transport be tested?

Compare PCB concentrations in air, water, and soil across locations and with atmospheric patterns.

Why compare PCB levels in nearby lakes at similar altitudes?

To test whether similar conditions produce similar deposition.

What could explain high PCBs in lakes connected to river systems?

Migratory fish such as salmon may transport PCBs from the ocean.

How could the migratory-fish PCB hypothesis be tested?

Compare lakes with and without migratory fish and test fish tissues.

What is biodiversity loss?

Decline in the variety or abundance of life, including species extinctions.

What are major drivers of biodiversity loss?

Habitat destruction, climate change, pollution, overexploitation, and invasive species.

Why are bees important to food production?

They pollinate many crops, including fruits and vegetables.

What is climate change?

Long-term changes in temperature and weather patterns.

What is the primary driver of recent global warming?

Human greenhouse gas emissions, especially from burning fossil fuels.

How does climate change affect freshwater availability?

It alters precipitation and can intensify droughts and water shortages.

What is a carbon footprint?

The greenhouse gas emissions associated with a person, household, activity, or product.

Which household activities affect carbon footprint?

Travel, home energy use, food, and consumption.

What information helps estimate car travel emissions?

Distance traveled and vehicle fuel efficiency.

How can dietary choices lower a carbon footprint?

Choose more plant-based foods and reduce food waste.

What is the carbon cycle?

Movement of carbon among the atmosphere, organisms, oceans, and land.

What does photosynthesis do in the carbon cycle?

Removes CO2 from air and stores carbon in organic matter.

What does respiration do in the carbon cycle?

Releases CO2 as organisms obtain energy.

What does decomposition do in the carbon cycle?

Returns carbon from dead matter to soil and atmosphere.

How do oceans participate in the carbon cycle?

They absorb and release atmospheric CO2.

How does deforestation affect atmospheric CO2?

It reduces carbon uptake and can release stored carbon.

Why does burning fossil fuels disrupt the carbon cycle?

It rapidly transfers long-stored carbon into the atmosphere.

What is the law of conservation of energy?

Energy cannot be created or destroyed; only transferred or transformed.

What is Earth's main external energy source?

The Sun.

What is a major source of Earth's internal heat?

Radioactive decay.

What is convection?

Transfer of heat through movement of fluids such as air or water.

How does energy enter most food webs?

Producers capture sunlight through photosynthesis.

How does energy move through trophic levels?

From producers to consumers, with usable energy declining at each transfer.

Does energy cycle through ecosystems like matter?

No; energy flows through and dissipates as heat, while matter cycles.

What is ATP?

Adenosine triphosphate, a molecule that supplies usable energy for cellular processes.

What are the inputs of photosynthesis?

Sunlight, water, and carbon dioxide.

What are the outputs of photosynthesis?

Sugars and oxygen.

What is endosymbiosis?

An evolutionary process in which one cell lives within another, contributing to complex eukaryotic cells.

What forms of nitrogen can plants commonly absorb?

Nitrate (NO3-) and ammonium (NH4+).

Why can most plants not use atmospheric nitrogen directly?

N2 must first be converted into biologically usable compounds.

What is nitrogen fixation?

Conversion of atmospheric N2 into ammonia or other usable nitrogen forms.

What is nitrogen assimilation?

Incorporation of absorbed nitrogen into organic molecules.

What is ammonification?

Conversion of organic nitrogen in waste or dead matter into ammonium.

What is nitrification?

Microbial conversion of ammonium into nitrite and then nitrate.

What is denitrification?

Microbial conversion of nitrate into gaseous nitrogen, returning it to the atmosphere.

What is a trophic cascade?

A chain of indirect ecosystem effects caused by changes at one trophic level.

What happens to kelp when sea otter populations increase?

Otters reduce urchins, allowing kelp to increase.

What happens to kelp when sea otter populations decline?

Urchins can increase and consume more kelp.

What is a keystone species?

A species with a disproportionately large effect on ecosystem structure.

What is a direct ecological effect?

An organism immediately affects another, such as a predator eating prey.

What is an indirect ecological effect?

An effect transmitted through one or more other species.

What is ecology?

Study of organisms and their interactions with each other and the environment.

What is a population?

Members of the same species living in an area.

What is a community?

Populations of different species interacting in an area.

What is an ecosystem?

A biological community together with its nonliving environment.

What is a biome?

A large region characterized by climate and typical ecosystems.

What is the biosphere?

All parts of Earth that support life.

What is the formula for population change?

Births + immigration - deaths - emigration.

What is population density?

Number of individuals per unit area or volume.

What are the three population dispersion patterns?

Clumped, uniform, and random.

What is population age structure?

The proportions of individuals in different age groups.

What is carrying capacity (K)?

The maximum population size an environment can sustainably support.

What are density-dependent limiting factors?

Factors whose effects increase with density, such as competition and disease.

What are density-independent limiting factors?

Factors such as severe weather or disasters that act regardless of population density.

What does exponential population growth look like?

A J-shaped curve under abundant resources.

What does logistic population growth look like?

An S-shaped curve that levels near carrying capacity.

What characterizes r-selected species?

Many offspring, early reproduction, and relatively little parental care.

What characterizes K-selected species?

Fewer offspring, later reproduction, and greater parental care.

What is a Type I survivorship curve?

High survival until old age, followed by increased mortality.

What is a Type II survivorship curve?

Roughly constant mortality risk throughout life.

What is a Type III survivorship curve?

High early mortality, with survivors living much longer.

How do predator and prey populations often cycle?

Prey increase, predators rise after a delay, then prey and predators decline.

What is camouflage?

An adaptation that helps an organism blend into its surroundings.

What is mimicry?

An organism resembling another to gain protection or another advantage.

What is symbiosis?

A close, sustained relationship between different species.

What is mutualism?

Both interacting species benefit.

What is commensalism?

One species benefits and the other is largely unaffected.

What is parasitism?

One species benefits while the host is harmed.

What is the Anthropocene?

A proposed geological epoch emphasizing the scale of human influence on Earth.

What is the Holocene?

The geological epoch following the last major ice age, during which human civilizations developed.

What is the Pleistocene?

The epoch marked by repeated glaciations before the Holocene.

What is habitat fragmentation?

Breaking a continuous habitat into smaller, isolated patches.

What is an invasive species?

A nonnative species that spreads and causes ecological or other harm.

How can fertilizer runoff harm coastal waters?

Excess nutrients trigger algal blooms and oxygen depletion.

What is eutrophication?

Nutrient enrichment that can cause algal blooms and low oxygen.

What is overfishing?

Harvesting fish faster than populations can replenish.

How can mining affect ecosystems?

Land disturbance, erosion, water pollution, and altered material cycles.

What is a population pyramid?

A graph showing the age and sex composition of a population.

What is ecological restoration?

Assisting the recovery of degraded ecosystems.

Why is biodiversity important for ecosystem resilience?

Diverse organisms can support ecosystem functions under changing conditions.

What is a toxicologist?

A scientist who studies harmful substances and their effects.

What is the difference between hazard and risk?

Hazard is potential to cause harm; risk is likelihood of harm under actual exposure.

What factors influence chemical exposure risk?

Toxicity, dose, duration, and route of exposure.

What are major routes of toxicant exposure?

Inhalation, ingestion, and skin contact.

What does EPA stand for?

Environmental Protection Agency.

What does PFAS stand for?

Per- and polyfluoroalkyl substances.

Why are PFAS called forever chemicals?

Many resist environmental breakdown and persist for long periods.

Does PFOA-free mean a product is free of all PFAS?

No; other PFAS may still be present.

What does BPA stand for?

Bisphenol A.

Why is BPA a concern?

It can interfere with hormone signaling.

Does BPA-free mean a product is free of potentially concerning substitutes?

No; alternatives such as BPS may be used.