OpenStem

@openstem · Joined Jul 2026

7420 public items8 groups

Flashcards9 cards

What is a producer, and give one example?1 / 9

A producer makes its own food, usually by photosynthesis — using sunlight energy to turn carbon dioxide and water into sugars. Grass, algae, and phytoplankton are all producers.

Environmental

Environmental · L2 · Ecosystems & Food Webs

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Flashcards8 cards

What does 'biodiversity' mean?1 / 8

Biodiversity is the variety of life in a place — how many different species live there, how genetically varied each species is, and how many different ecosystems exist across a region.

Environmental

Environmental · L2 · Biodiversity & Species Loss

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Flashcards8 cards

What is a solar photovoltaic (PV) cell made from, and what does it do?1 / 8

A PV cell is a thin wafer of silicon, a semiconductor material. When sunlight (made of particles called photons) strikes the silicon, it knocks electrons loose, and those freed electrons flow as an electric current — the photovoltaic effect.

Environmental

Environmental · L2 · How Renewable Energy Systems Work

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Flashcards8 cards

What are fossil fuels?1 / 8

Coal, oil, and natural gas — energy sources formed from the buried, compressed remains of ancient organisms that lived millions of years ago.

Environmental

Environmental · L2 · Fossil Fuels & Nonrenewable Resources

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Flashcards8 cards

What is a primary air pollutant?1 / 8

A primary pollutant is released directly into the air from a source — for example, soot and carbon monoxide from a car's exhaust, or sulfur dioxide from burning coal.

Environmental

Environmental · L2 · Air Pollution: Sources & Smog

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Flashcards8 cards

What is point source water pollution?1 / 8

Pollution that enters water from a single, identifiable source — like a pipe discharging waste directly from a factory or a sewage treatment plant outfall.

Environmental

Environmental · L2 · Water Pollution & Treatment

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Flashcards9 cards

What are the four main material streams most curbside recycling programs sort?1 / 9

Paper and cardboard, glass, plastic, and metal. Each material behaves differently when reprocessed, so keeping them separate (or sorting them later) matters.

Environmental

Environmental · L2 · Recycling Systems & Materials

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Flashcards8 cards

Why is topsoil worth protecting in the first place?1 / 8

Topsoil holds the organic matter and nutrients that crops need, and it can take hundreds to thousands of years to form naturally. Once it erodes away, replacing it isn't realistic on a human timescale — so protecting the topsoil that's already there matters far more than trying to rebuild it.

Environmental

Environmental · L2 · Soil Conservation & Erosion Control

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Flashcards8 cards

What is a tectonic plate boundary?1 / 8

A tectonic plate boundary is the edge where two of Earth's rigid crustal plates meet. Because the plates are constantly moving — colliding, pulling apart, or sliding past each other — boundaries are where most of the planet's earthquake and volcanic activity happens.

Environmental

Environmental · L2 · Earthquakes & Plate Boundaries

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Flashcards8 cards

Where is the ozone layer located, and what is it made of?1 / 8

The ozone layer sits in the stratosphere, roughly 15 to 35 kilometers above Earth's surface. It's a region where ozone molecules (O₃) are unusually concentrated compared to the rest of the atmosphere, though even there ozone is a fairly trace gas.

Environmental

Environmental · L2 · The Ozone Layer & UV Protection

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Flashcards8 cards

What does it mean for a species to be 'invasive'?1 / 8

An invasive species is a non-native organism introduced to a new area — usually by human activity — that spreads rapidly and causes ecological or economic harm there. Not every introduced species becomes invasive; the label applies specifically to ones that cause real damage.

Environmental

Environmental · L2 · Invasive Species

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Flashcards8 cards

What mainly drives surface ocean currents?1 / 8

Wind. Persistent global wind patterns drag against the ocean surface and push the top layer of water along with them, setting up large, roughly circular current systems called gyres in each ocean basin.

Environmental

Environmental · L2 · Ocean Currents & Marine Ecosystems

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Flashcards8 cards

What does 'sustainable agriculture' mean, in simple terms?1 / 8

Farming methods designed to produce food long-term without depleting the soil, water, and biodiversity that future harvests depend on — meeting today's needs without undermining tomorrow's ability to farm the same land.

Environmental

Environmental · L2 · Sustainable Agriculture

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Flashcards8 cards

How does a glacier form?1 / 8

A glacier forms where snowfall exceeds melting year after year. Fresh snow gets buried and compacted by the weight of new snow above it, first turning into a grainy intermediate stage called firn, then — after decades of further compression squeezing out the air — into dense glacial ice.

Environmental

Environmental · L2 · Glaciers & Ice Sheets

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Flashcards8 cards

What officially makes a region a desert?1 / 8

A desert is defined by low precipitation — typically less than about 25 centimeters (10 inches) of rain per year — not necessarily by heat. Deserts can be scorching (the Sahara) or bitterly cold (parts of the Gobi, and even Antarctica, which is technically the world's largest desert).

Environmental

Environmental · L2 · Desert Ecosystems & Adaptations

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Flashcards8 cards

What defines a wetland?1 / 8

A wetland is land that's saturated with water — permanently or for at least part of the year — long enough to support plants and soils adapted to those wet conditions, called hydrophytic (water-loving) vegetation.

Environmental

Environmental · L2 · Wetland Ecosystems

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Flashcards8 cards

What is a coral polyp?1 / 8

A coral polyp is a tiny, soft-bodied animal — related to jellyfish and sea anemones — that builds a hard, cup-shaped skeleton of calcium carbonate around itself. Millions of polyps living together, generation after generation, build up the massive rocky structures we call a coral reef.

Environmental

Environmental · L2 · Coral Reef Ecology

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Flashcards8 cards

What does insulation actually do, physically?1 / 8

Insulation slows the conduction of heat through a wall, roof, or floor by trapping pockets of air (or another low-conductivity material) that resist heat flow. In winter that keeps indoor heat from escaping; in summer it keeps outdoor heat from getting in — either way, the heating or cooling system has to work less.

Environmental

Environmental · L2 · Energy Efficiency in Buildings

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What is a carbon footprint?1 / 8

A carbon footprint is the total amount of greenhouse gases — expressed as an equivalent amount of carbon dioxide (CO₂e) — that a person, household, product, or activity is responsible for releasing, directly and indirectly.

Environmental

Environmental · L2 · Carbon Footprint

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Flashcards8 cards

What three axes do we usually compare energy sources on?1 / 8

Cost (both upfront and ongoing), emissions (how much greenhouse gas and pollution are released over the source's lifecycle), and reliability (whether it can supply power on demand, or only when conditions — like sun or wind — allow).

Environmental

Environmental · L2 · Comparing Energy Sources

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Flashcards8 cards

What is the urban heat island effect?1 / 8

The urban heat island effect is the tendency for cities to be noticeably warmer than the rural areas surrounding them — sometimes several degrees warmer, especially at night — because of how built-up areas absorb and retain heat differently than natural landscapes.

Environmental

Environmental · L2 · Urban Heat Island Effect

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Flashcards8 cards

What is groundwater, and where is it stored?1 / 8

Groundwater is water that has soaked into the ground and now fills the spaces between soil particles and cracks in rock beneath the surface. It's not stored in vast open caverns everywhere — mostly it fills the tiny pore spaces of permeable soil and rock, like water in a sponge.

Environmental

Environmental · L2 · Groundwater & Aquifers

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Flashcards8 cards

What is the single largest global driver of deforestation today?1 / 8

Agricultural expansion is the largest driver worldwide — clearing forest for cattle ranching, and for crops like soy and oil palm, accounts for a bigger share of global forest loss than logging or infrastructure combined.

Environmental

Environmental · L2 · Deforestation: Causes & Effects

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Flashcards8 cards

What is habitat fragmentation?1 / 8

Habitat fragmentation is the breaking up of a large, continuous habitat into smaller, separated patches — typically caused by roads, farmland, or development cutting through what was once unbroken wilderness.

Environmental

Environmental · L2 · Wildlife Corridors & Habitat Fragmentation

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Flashcards8 cards

What counts as e-waste, and why is it one of the fastest-growing waste streams?1 / 8

E-waste is any discarded electronic device — phones, computers, TVs, and appliances. It's growing fast because people replace electronics more often than ever, driven by falling prices, quickly changing technology, and devices designed with short usable lifespans.

Environmental

Environmental · L2 · Electronic Waste

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Flashcards8 cards

What is environmental justice, in one sentence?1 / 8

Environmental justice is the idea that all people — regardless of race, income, or background — deserve equal protection from environmental hazards and equal access to a healthy environment.

Environmental

Environmental · L2 · Environmental Justice

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Flashcards9 cards

What is a trophic level?1 / 9

A feeding position in a food chain — producers (level 1), primary consumers (level 2), secondary consumers (level 3), tertiary consumers (level 4), and so on — grouped by how many energy transfers separate an organism from the Sun.

Environmental

Environmental · L3 · Trophic Levels & Energy Pyramids

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Flashcards9 cards

Why do plants and animals need a 'nitrogen cycle' at all, when 78% of the atmosphere is already nitrogen gas (N₂)?1 / 9

N₂ is extremely stable (a strong triple bond) and cannot be used directly by most organisms. It has to be 'fixed' — converted into a reactive form like ammonia — before living things can build proteins and DNA from it.

Environmental

Environmental · L3 · The Nitrogen Cycle

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Flashcards9 cards

What is the single biggest structural difference between the phosphorus cycle and the nitrogen or carbon cycles?1 / 9

Phosphorus has no significant atmospheric phase — it doesn't exist as a gas in any biologically important form, so it can't move through the air the way N₂ or CO₂ does. It cycles almost entirely through rock, soil, and water.

Environmental

Environmental · L3 · The Phosphorus Cycle

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Flashcards9 cards

What does exponential population growth look like, and when does it happen?1 / 9

A J-shaped curve where population size accelerates without limit — it happens when resources are effectively unlimited, so the growth rate stays constant regardless of how large the population gets.

Environmental

Environmental · L3 · Population Ecology & Carrying Capacity

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