Unit #3 Study Guide: Ecosystems, Food Chains, Nutrient Cycles, and Human Impact

Vocabulary practice flashcards covering biomes, food webs, trophic levels, energy transfer, nutrient cycles, and environmental concepts from Unit #3.

Desert

The hottest of all biomes; extremely dry with scarce water, where tough plants have needles instead of leaves for protection, and animals survive by remaining underground or in the shade.

Permafrost

A layer of permanently frozen soil found in the tundra biome.

Tundra

A biome characterized by cold temperatures and permafrost, where only a few specialized plant and animal types survive, including grasses, small shrubs, lichen, mountain goats, sheep, elk, and lemmings.

Chaparral

A temperate coastal biome known as the "Wild West" (found in California), dominated by dense evergreen shrubs and inhabited by coyotes, jackrabbits, mule deer, lizards, toads, and praying mantises.

Temperate Deciduous Forest

A biome with an average temperature of $50^\circ\text{F}$, $30\text{--}60\text{ inches}$ of rainfall per year, and $4$ distinct seasons; contains $5$ zones of plants (trees, shrubs, flowers, berries, plants, moss) and animals that hibernate in winter.

Coniferous Forest

A forest biome featuring long, cold winters and heavy snowfall; dominated by evergreen trees (pine, spruce, fir, hemlock) whose dense canopy allows little light to reach the forest floor, where mosses, ferns, and lichens grow.

Tropical Forest

A warm, equatorial biome receiving $100+\text{ inches}$ of rain per year with the greatest diversity of tree species in the world; home to more than $\frac{1}{2}$ of Earth's plant and animal species and the source of $\frac{1}{4}$ of all medicines.

Temperate Grassland

Also called a prairie; a biome characterized by deep, nutrient-rich soil that supports a wide variety of grass species and animals such as bison, coyotes, eagles, bobcats, gray wolves, wild turkeys, and geese.

Savanna

A tropical biome found in Africa, Australia, and South America with warm temperatures all year and two distinct seasons (wet and dry), receiving insufficient rainfall to support a forest.

Estuary

An area where land meets the sea and a freshwater stream or river meets a saltwater ocean; supports grasses, aquatic plants, shorebirds, fish, crabs, lobsters, marine mammals, and clams.

Intertidal Ocean

A coastal tidal saltwater area where land meets the sea (including rocky cliffs, sandy beaches, and wetlands); home to seagrass, seaweed, algae, starfish, sea urchins, and coral.

Coral Reefs

Underwater structures built by tiny animals that host plants such as phytoplankton, mangroves, and seagrass, and support fish, seabirds, sponges, jellyfish, shrimp, lobsters, and crabs.

Open Ocean

A marine biome where the majority of life exists in sunlit waters; inhabited by algae, diatoms, fish, whales, sharks, dolphins, squid, and plankton.

Deep Sea Vents

Spots on the ocean floor where hot gas and minerals discharge from Earth's interior under high pressure, near-freezing temperatures, and total darkness; life here relies on hydrogen sulfide.

Freshwater Biome (Ponds, Lakes, Streams, Rivers)

An aquatic biome containing less than $1\%$ salt; supports over $700$ fish species, grasses, aquatic plants, crocodiles, hippos, turtles, frogs, and many insects.

Rain Shadow

A dry area on the leeward side of a mountain formed because warm, moist air cools and condenses as it rises over the windward side, dropping most of its rain before advancing as dry air.

Food Web

An ecological model that illustrates the complex network of feeding interactions among organisms in a community.

Trophic Levels

Each progressive step in the transfer of energy and matter within a food web, typically running out of energy after $4$ or $5$ levels.

Producers

Plants and other autotrophic organisms that manufacture their own food through photosynthesis; also referred to as primary producers.

Consumers

Organisms that obtain chemical energy by eating plants and other consumers.

Photosynthesis

The biological process by which producers (plants) synthesize their own food using sunlight.

Primary Consumers

Herbivores that feed directly on producers (plants).

Secondary Consumers

Organisms that feed on primary consumers (animals that eat plants).

Autotrophs

Organisms that produce their own food.

Heterotrophs

Animals that cannot make their own food and must consume other organisms; also known as consumers.

Herbivores

Consumers that eat plants only.

Omnivores

Consumers that eat both plants and animals (feeding on both producers and consumers).

Carnivores

Consumers that eat meat.

Scavengers

Animals that consume the bodies of dead animals.

Decomposers

Organisms that break down the cells of dead plants and animals, returning vital nutrients to the earth.

Keystone Species

The most important species in an ecosystem, exerting strong control on community structure.

10% Energy Transfer Rule

The principle stating that only approximately $10\%$ of energy is transferred from one trophic level to the next; the remaining $90\%$ is used for life functions or lost as heat.

Microclimates

Climate conditions in a small, localized area that differ significantly from the general climate of the surrounding region.

Biotic Factors

The living biological components of an ecosystem.

Abiotic Factors

The non-living physical and chemical components that influence living organisms (such as sunlight, temperature, and wind speed).

Biomass

Dried organic material that ecological scientists weigh and measure to study ecosystems.

Biological Magnification

The increasing concentration or density of toxic substances in organisms at progressively higher trophic levels.

Deforestation

The large-scale clearing of forests, which disrupts the natural water and carbon cycles.

Climate

The long-term weather pattern of an area, determined primarily by precipitation and temperature.

pH Scale

A measurement scale from $0$ to $14$ indicating chemical acidity or alkalinity, where values below $7$ are acidic, $7$ is neutral, and values above $7$ are alkaline.

Carbon Cycle

The biogeochemical cycle by which carbon is exchanged through photosynthesis, animal respiration, plant and root respiration, decay organisms, and factory emissions.

Water Cycle

The continuous movement of water on, above, and below Earth's surface through evaporation, transpiration, condensation, precipitation, surface runoff, infiltration into groundwater, and plant uptake.

Nitrogen Cycle

The ecological cycle by which nitrogen moves between atmospheric, terrestrial, and plant systems through mineralization into ammonium, nitrification into nitrites and nitrates, plant consumption, and denitrification by bacteria.

Energy and Nutrient Dynamics

The fundamental ecological principle that energy flows continuously in one direction through an ecosystem, while nutrients cycle repeatedly.

Food Chain Length Limitation

The limitation of food chains to generally $4\text{ to }5$ trophic levels because energy transfers are inefficient and insufficient energy remains to support higher levels.

Consumer Energy Partitioning (Caterpillar Model)

The allocation of ingested food energy ($200\,\text{J}$), where $100\,\text{J}$ is eliminated as feces, $67\,\text{J}$ is lost through cellular respiration, and the remaining $33\,\text{J}$ ($16.5\%$) is converted into new biomass (growth).